{"id":493,"date":"2022-09-21T06:14:54","date_gmt":"2022-07-23T13:58:33","guid":{"rendered":"https:\/\/www.silicloud.com\/ja\/blog\/index.php\/2023\/11\/30\/java%e3%83%97%e3%83%ad%e3%82%b0%e3%83%a9%e3%83%9f%e3%83%b3%e3%82%b0%e3%81%ae%e9%9d%a2%e6%8e%a5%e3%81%a7%e3%82%88%e3%81%8f%e8%81%9e%e3%81%8b%e3%82%8c%e3%82%8b50%e3%81%ae%e8%b3%aa%e5%95%8f%e3%81%ae\/"},"modified":"2025-08-01T00:00:55","modified_gmt":"2025-07-31T15:00:55","slug":"java%e3%83%97%e3%83%ad%e3%82%b0%e3%83%a9%e3%83%9f%e3%83%b3%e3%82%b0%e3%81%ae%e9%9d%a2%e6%8e%a5%e3%81%a7%e3%82%88%e3%81%8f%e8%81%9e%e3%81%8b%e3%82%8c%e3%82%8b50%e3%81%ae%e8%b3%aa%e5%95%8f%e3%81%ae","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/ja\/blog\/java%e3%83%97%e3%83%ad%e3%82%b0%e3%83%a9%e3%83%9f%e3%83%b3%e3%82%b0%e3%81%ae%e9%9d%a2%e6%8e%a5%e3%81%a7%e3%82%88%e3%81%8f%e8%81%9e%e3%81%8b%e3%82%8c%e3%82%8b50%e3%81%ae%e8%b3%aa%e5%95%8f%e3%81%ae\/","title":{"rendered":"Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u9762\u63a5\u3067\u3088\u304f\u805e\u304b\u308c\u308b50\u306e\u8cea\u554f\u306e\u30c8\u30c3\u30d7"},"content":{"rendered":"

\u3042\u3044\u3055\u3064<\/h3>\n

\u3082\u3057Java\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u5f79\u5272\u306e\u9762\u63a5\u3092\u53d7\u3051\u308b\u306a\u3089\u3070\u3001\u304a\u305d\u3089\u304f\u3042\u306a\u305f\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u30b9\u30ad\u30eb\u304c\u30c6\u30b9\u30c8\u3055\u308c\u307e\u3059\u3002Java\u306e\u521d\u5fc3\u8005\u3067\u3042\u308d\u3046\u3068\u3001\u30a8\u30ad\u30b9\u30d1\u30fc\u30c8\u30d7\u30ed\u30b0\u30e9\u30de\u3067\u3042\u308d\u3046\u3068\u3001\u3053\u306e\u8a18\u4e8b\u306f\u3044\u304f\u3064\u304b\u306e\u4e00\u822c\u7684\u306aJava\u306e\u9762\u63a5\u306e\u8cea\u554f\u3068\u56de\u7b54\u3092\u63d0\u4f9b\u3057\u3001\u6e96\u5099\u3092\u652f\u63f4\u3057\u307e\u3059\u3002<\/p>\n

Java\u3067\u6587\u5b57\u5217\u3092\u9006\u306b\u3059\u308b\u65b9\u6cd5\u306f\u3069\u3046\u3059\u308c\u3070\u3044\u3044\u3067\u3059\u304b\uff1f<\/h2>\n

String\u30af\u30e9\u30b9\u306b\u306freverse()\u3068\u3044\u3046\u30e6\u30fc\u30c6\u30a3\u30ea\u30c6\u30a3\u30e1\u30bd\u30c3\u30c9\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u3057\u304b\u3057\u3001\u6587\u5b57\u5217\u304b\u3089\u6587\u5b57\u914d\u5217\u3092\u4f5c\u6210\u3057\u3001\u5f8c\u308d\u304b\u3089\u5148\u982d\u306b\u5411\u304b\u3063\u3066\u30a4\u30c6\u30ec\u30fc\u30c8\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6587\u5b57\u3092\u6587\u5b57\u5217\u30d3\u30eb\u30c0\u30fc\u306b\u8ffd\u52a0\u3057\u3001\u6700\u7d42\u7684\u306b\u9006\u3055\u307e\u306e\u6587\u5b57\u5217\u3092\u8fd4\u3059\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n

\u4ee5\u4e0b\u306e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u306f\u3001\u6587\u5b57\u5217\u3092\u53cd\u8ee2\u3055\u305b\u308b\u65b9\u6cd5\u306e\u4e00\u3064\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n

public<\/span> class<\/span> StringPrograms<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tString<\/span> str =<\/span> \"123\"<\/span>;<\/span>\r\n\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>reverse<\/span>(<\/span>str)<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> String<\/span> reverse<\/span>(<\/span>String<\/span> in)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>in ==<\/span> null<\/span>)<\/span>\r\n\t\t\tthrow<\/span> new<\/span> IllegalArgumentException<\/span>(<\/span>\"Null is not valid input\"<\/span>)<\/span>;<\/span>\r\n\r\n\t\tStringBuilder<\/span> out =<\/span> new<\/span> StringBuilder<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\t\tchar<\/span>[<\/span>]<\/span> chars =<\/span> in.<\/span>toCharArray<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\t\tfor<\/span> (<\/span>int<\/span> i =<\/span> chars.<\/span>length -<\/span> 1<\/span>;<\/span> i >=<\/span> 0<\/span>;<\/span> i--<\/span>)<\/span>\r\n\t\t\tout.<\/span>append<\/span>(<\/span>chars[<\/span>i]<\/span>)<\/span>;<\/span>\r\n\r\n\t\treturn<\/span> out.<\/span>toString<\/span>(<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
\u30e1\u30bd\u30c3\u30c9\u5185\u306b\u30cc\u30eb\u30c1\u30a7\u30c3\u30af\u3092\u8ffd\u52a0\u3057\u3001\u6587\u5b57\u3092\u9023\u7d50\u3059\u308b\u305f\u3081\u306bStringBuilder\u3092\u4f7f\u7528\u3059\u308b\u3068\u30dc\u30fc\u30ca\u30b9\u30dd\u30a4\u30f3\u30c8\u304c\u52a0\u7b97\u3055\u308c\u307e\u3059\u3002\u305f\u3060\u3057\u3001Java\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306f0\u304b\u3089\u59cb\u307e\u308b\u305f\u3081\u3001for\u30eb\u30fc\u30d7\u3067\u306fchars.length – 1\u304b\u3089\u958b\u59cb\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n
2. Java\u3092\u4f7f\u7528\u305b\u305a\u306b\u3001\u4e8c\u3064\u306e\u6570\u5b57\u3092\u5165\u308c\u66ff\u3048\u308b\u65b9\u6cd5\u306f\u3042\u308a\u307e\u3059\u304b\uff1f<\/h2>\n
\u4e09\u3064\u306e\u5909\u6570\u3092\u4f7f\u7528\u305b\u305a\u306b\u6570\u5024\u3092\u4ea4\u63db\u3059\u308b\u65b9\u6cd5\u306f\u3001\u30b3\u30fc\u30c9\u3067\u8996\u899a\u7684\u306b\u8868\u73fe\u3055\u308c\u308b\u3068\u3088\u308a\u7406\u89e3\u3057\u3084\u3059\u3044\u4e09\u6bb5\u968e\u306e\u30d7\u30ed\u30bb\u30b9\u3067\u3059\u3002<\/p>\n
b = b + a; \/\/ now b is sum of both the numbers\r\na = b - a; \/\/ b - a = (b + a) - a = b (a is swapped)\r\nb = b - a; \/\/ (b + a) - b = a (b is swapped)\r\n<\/code><\/pre>\n
\u6b21\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001\u6570\u5024\u306e\u4ea4\u63db\u30e1\u30bd\u30c3\u30c9\u3092\u5b9f\u88c5\u3059\u308b\u4e00\u3064\u306e\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
public<\/span> class<\/span> SwapNumbers<\/span> {<\/span>\r\n\r\npublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\tint<\/span> a =<\/span> 10<\/span>;<\/span>\r\n\tint<\/span> b =<\/span> 20<\/span>;<\/span>\r\n\r\n    System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"a is \"<\/span> +<\/span> a +<\/span> \" and b is \"<\/span> +<\/span> b)<\/span>;<\/span>\r\n\r\n\ta =<\/span> a +<\/span> b;<\/span>\r\n\tb =<\/span> a -<\/span> b;<\/span>\r\n\ta =<\/span> a -<\/span> b;<\/span>\r\n\r\n    System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"After swapping, a is \"<\/span> +<\/span> a +<\/span> \" and b is \"<\/span> +<\/span> b)<\/span>;<\/span>\r\n    }<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
\u51fa\u529b\u7d50\u679c\u306f\u6574\u6570\u5024\u304c\u5165\u308c\u66ff\u308f\u3063\u305f\u3053\u3068\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
<\/code><\/pre>\n
Output<\/div>\n
<\/code><\/pre>\n
a is 10 and b is 20 After swapping, a is 20 and b is 10<\/p>\n
<\/code><\/pre>\n
3. \u6587\u5b57\u5217\u306b\u6bcd\u97f3\u304c\u542b\u307e\u308c\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306eJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
\u4ee5\u4e0b\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u6587\u5b57\u5217\u306b\u6bcd\u97f3\u304c\u542b\u307e\u308c\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u305f\u3081\u306b\u6b63\u898f\u8868\u73fe\u3092\u4f7f\u7528\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
public<\/span> class<\/span> StringContainsVowels<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>stringContainsVowels<\/span>(<\/span>\"Hello\"<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>stringContainsVowels<\/span>(<\/span>\"TV\"<\/span>)<\/span>)<\/span>;<\/span> \/\/ false<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> boolean<\/span> stringContainsVowels<\/span>(<\/span>String<\/span> input)<\/span> {<\/span>\r\n\t\treturn<\/span> input.<\/span>toLowerCase<\/span>(<\/span>)<\/span>.<\/span>matches<\/span>(<\/span>\".*[aeiou].*\"<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
\u4e0e\u3048\u3089\u308c\u305f\u6570\u304c\u7d20\u6570\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306eJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
\u4e0e\u3048\u3089\u308c\u305f\u6570n\u3092\u30012\u304b\u3089n\/2\u307e\u3067\u306e\u6570\u3067\u5272\u308a\u3001\u4f59\u308a\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3082\u3057\u4f59\u308a\u304c0\u3067\u3042\u308c\u3070\u3001\u305d\u308c\u306f\u7d20\u6570\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u4ee5\u4e0b\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u4e0e\u3048\u3089\u308c\u305f\u6570\u304c\u7d20\u6570\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308b\u4e00\u3064\u306e\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
public<\/span> class<\/span> PrimeNumberCheck<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>isPrime<\/span>(<\/span>19<\/span>)<\/span>)<\/span>;<\/span> \/\/ true<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>isPrime<\/span>(<\/span>49<\/span>)<\/span>)<\/span>;<\/span> \/\/ false<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> boolean<\/span> isPrime<\/span>(<\/span>int<\/span> n)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>n ==<\/span> 0<\/span> ||<\/span> n ==<\/span> 1<\/span>)<\/span> {<\/span>\r\n\t\t\treturn<\/span> false<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t\tif<\/span> (<\/span>n ==<\/span> 2<\/span>)<\/span> {<\/span>\r\n\t\t\treturn<\/span> true<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t\tfor<\/span> (<\/span>int<\/span> i =<\/span> 2<\/span>;<\/span> i <=<\/span> n \/<\/span> 2<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>\r\n\t\t\tif<\/span> (<\/span>n %<\/span> i ==<\/span> 0<\/span>)<\/span> {<\/span>\r\n\t\t\t\treturn<\/span> false<\/span>;<\/span>\r\n\t\t\t}<\/span>\r\n\t\t}<\/span>\r\n\r\n\t\treturn<\/span> true<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3053\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u306f\u52d5\u4f5c\u3059\u308b\u304c\u3001\u30e1\u30e2\u30ea\u3068\u6642\u9593\u306e\u52b9\u7387\u304c\u3042\u307e\u308a\u3088\u304f\u306a\u3044\u3002\u4e0e\u3048\u3089\u308c\u305f\u6570N\u306b\u5bfe\u3057\u3066\u30012\u304b\u3089\u221aN\uff08N\u306e\u5e73\u65b9\u6839\uff09\u306e\u9593\u306b\u3001\u305d\u308c\u3067\u5747\u7b49\u306b\u5272\u308a\u7b97\u3067\u304d\u308b\u7d20\u6570M\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u3001N\u306f\u7d20\u6570\u3067\u306f\u306a\u3044\u3068\u8003\u3048\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
5. \u518d\u5e30\u3092\u4f7f\u7528\u3057\u3066\u30d5\u30a3\u30dc\u30ca\u30c3\u30c1\u6570\u5217\u3092\u5370\u5237\u3059\u308b\u305f\u3081\u306eJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
\u30d5\u30a3\u30dc\u30ca\u30c3\u30c1\u6570\u5217\u306f\u3001\u5404\u6570\u304c\u524d\u306e2\u3064\u306e\u6570\u306e\u5408\u8a08\u3067\u3042\u308b\u6570\u5217\u3067\u3059\u3002\u3053\u306e\u4f8b\u3067\u306f\u3001\u6570\u5217\u306f0\u30681\u3067\u59cb\u307e\u308a\u307e\u3059\u3002\u6b21\u306e\u30b3\u30fc\u30c9\u306e\u4f8b\u306f\u3001for\u30eb\u30fc\u30d7\u3092\u4f7f\u7528\u3057\u3066\u30d5\u30a3\u30dc\u30ca\u30c3\u30c1\u6570\u5217\u3092\u8868\u793a\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
public<\/span> class<\/span> PrintFibonacci<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> printFibonacciSequence<\/span>(<\/span>int<\/span> count)<\/span> {<\/span>\r\n\t\tint<\/span> a =<\/span> 0<\/span>;<\/span>\r\n\t\tint<\/span> b =<\/span> 1<\/span>;<\/span>\r\n\t\tint<\/span> c =<\/span> 1<\/span>;<\/span>\r\n\r\n\t\tfor<\/span> (<\/span>int<\/span> i =<\/span> 1<\/span>;<\/span> i <=<\/span> count;<\/span> i++<\/span>)<\/span> {<\/span>\r\n\t\t\tSystem<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>a +<\/span> \", \"<\/span>)<\/span>;<\/span>\r\n\r\n            a =<\/span> b;<\/span>\r\n\t\t\tb =<\/span> c;<\/span>\r\n\t\t\tc =<\/span> a +<\/span> b;<\/span>\r\n\t\t}<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n    \tprintFibonacciSequence<\/span>(<\/span>10<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
<\/code><\/pre>\n
Output<\/div>\n
<\/code><\/pre>\n
0, 1, 1, 2, 3, 5, 8, 13, 21, 34,<\/p>\n
<\/code><\/pre>\n
\u30d5\u30a3\u30dc\u30ca\u30c3\u30c1\u6570\u5217\u3092\u51fa\u529b\u3059\u308b\u305f\u3081\u306b\u518d\u5e30\u3082\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u306a\u305c\u306a\u3089\u3001\u30d5\u30a3\u30dc\u30ca\u30c3\u30c1\u6570\u306f\u76f4\u524d\u306e\u4e8c\u3064\u306e\u6570\u3092\u8db3\u3059\u3053\u3068\u3067\u751f\u6210\u3055\u308c\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n
F(N) = F(N-1) + F(N-2)\r\n<\/code><\/pre>\n
\u4ee5\u4e0b\u306e\u4f8b\u984c\u30af\u30e9\u30b9\u306f\u300110\u500b\u306e\u6570\u5b57\u304b\u3089\u306a\u308b\u30d5\u30a3\u30dc\u30ca\u30c3\u30c1\u6570\u5217\u3092\u518d\u5e30\u3092\u4f7f\u3063\u3066\u8a08\u7b97\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
public<\/span> class<\/span> PrintFibonacciRecursive<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> int<\/span> fibonacci<\/span>(<\/span>int<\/span> count)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>count <=<\/span> 1<\/span>)<\/span>\r\n\t\t\treturn<\/span> count;<\/span>\r\n\r\n\t\treturn<\/span> fibonacci<\/span>(<\/span>count -<\/span> 1<\/span>)<\/span> +<\/span> fibonacci<\/span>(<\/span>count -<\/span> 2<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span> args[<\/span>]<\/span>)<\/span> {<\/span>\r\n    \tint<\/span> seqLength =<\/span> 10<\/span>;<\/span>\r\n\r\n    \tSystem<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>\"A Fibonacci sequence of \"<\/span> +<\/span> seqLength +<\/span> \" numbers: \"<\/span>)<\/span>;<\/span>\r\n\r\n    \tfor<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> seqLength;<\/span> i++<\/span>)<\/span> {<\/span>\r\n      \t    System<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>fibonacci<\/span>(<\/span>i)<\/span> +<\/span> \" \"<\/span>)<\/span>;<\/span>\r\n    \t}<\/span>\r\n  \t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
<\/code><\/pre>\n
Output<\/div>\n
<\/code><\/pre>\n
A Fibonacci sequence of 10 numbers: 0 1 1 2 3 5 8 13 21 34<\/p>\n
<\/code><\/pre>\n
6. Java\u3067\u6574\u6570\u306e\u30ea\u30b9\u30c8\u304c\u5947\u6570\u306e\u307f\u3092\u542b\u3093\u3067\u3044\u308b\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f<\/h2>\n
\u300c\u5404\u8981\u7d20\u304c\u5947\u6570\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306b\u3001for\u30eb\u30fc\u30d7\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u300d<\/p>\n
public<\/span> static<\/span> boolean<\/span> onlyOddNumbers<\/span>(<\/span>List<\/span><<\/span>Integer<\/span>><\/span><\/span> list)<\/span> {<\/span>\r\n\tfor<\/span> (<\/span>int<\/span> i :<\/span> list)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>i %<\/span> 2<\/span> ==<\/span> 0<\/span>)<\/span>\r\n\t\t\treturn<\/span> false<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\treturn<\/span> true<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u30ea\u30b9\u30c8\u304c\u5927\u304d\u3044\u5834\u5408\u306f\u3001\u6b21\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306b\u793a\u3059\u3088\u3046\u306b\u3001\u9ad8\u901f\u306a\u51e6\u7406\u306e\u305f\u3081\u306b\u4e26\u5217\u30b9\u30c8\u30ea\u30fc\u30e0\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
public<\/span> static<\/span> boolean<\/span> onlyOddNumbers<\/span>(<\/span>List<\/span><<\/span>Integer<\/span>><\/span><\/span> list)<\/span> {<\/span>\r\n\treturn<\/span> list\r\n\t\t\t.<\/span>parallelStream<\/span>(<\/span>)<\/span> \/\/ parallel stream for faster processing<\/span>\r\n\t\t\t.<\/span>anyMatch<\/span>(<\/span>x -><\/span> x %<\/span> 2<\/span> !=<\/span> 0<\/span>)<\/span>;<\/span> \/\/ return as soon as any elements match the condition<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u6574\u6570\u304c\u5947\u6570\u304b\u3069\u3046\u304b\u3092\u6c7a\u5b9a\u3059\u308b\u6570\u5b66\u7684\u306a\u539f\u7406\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u305f\u3044\u5834\u5408\u306f\u3001Wikipedia\u306e\u5270\u4f59\u6f14\u7b97\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
7. Java\u3067\u6587\u5b57\u5217\u304c\u56de\u6587\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f<\/h2>\n
\u56de\u6587\uff08\u304b\u3044\u3076\u3093\uff09\u3068\u306f\u3001\u6587\u5b57\u5217\u3092\u9006\u304b\u3089\u8aad\u3093\u3067\u3082\u540c\u3058\u306b\u306a\u308b\u6587\u5b57\u5217\u306e\u3053\u3068\u3067\u3059\u3002\u56de\u6587\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u305f\u3081\u306b\u306f\u3001\u5165\u529b\u3055\u308c\u305f\u6587\u5b57\u5217\u3092\u9006\u306b\u3057\u3066\u7d50\u679c\u304c\u5165\u529b\u3068\u540c\u3058\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u4f8b\u984c\u30b3\u30fc\u30c9\u306f\u3001String\u30af\u30e9\u30b9\u306echarAt(int index)\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u56de\u6587\u6587\u5b57\u5217\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
boolean<\/span> checkPalindromeString<\/span>(<\/span>String<\/span> input)<\/span> {<\/span>\r\n\tboolean<\/span> result =<\/span> true<\/span>;<\/span>\r\n\tint<\/span> length =<\/span> input.<\/span>length<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\tfor<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> length\/<\/span>2<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>input.<\/span>charAt<\/span>(<\/span>i)<\/span> !=<\/span> input.<\/span>charAt<\/span>(<\/span>length -<\/span> i -<\/span> 1<\/span>)<\/span>)<\/span> {<\/span>\r\n\t\t\tresult =<\/span> false<\/span>;<\/span>\r\n\t\t\tbreak<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t}<\/span>\r\n\r\n\treturn<\/span> result;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
8. Java\u3067\u6587\u5b57\u5217\u304b\u3089\u30b9\u30da\u30fc\u30b9\u3092\u524a\u9664\u3059\u308b\u306b\u306f\u3001\u3069\u306e\u3088\u3046\u306b\u3059\u308c\u3070\u3044\u3044\u3067\u3059\u304b\uff1f<\/h2>\n
\u4ee5\u4e0b\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001Character.isWhitespace()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u6587\u5b57\u5217\u304b\u3089\u30b9\u30da\u30fc\u30b9\u3092\u524a\u9664\u3059\u308b\u65b9\u6cd5\u306e\u4e00\u3064\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
String<\/span> removeWhiteSpaces<\/span>(<\/span>String<\/span> input)<\/span> {<\/span>\r\n\tStringBuilder<\/span> output =<\/span> new<\/span> StringBuilder<\/span>(<\/span>)<\/span>;<\/span>\r\n\t\r\n\tchar<\/span>[<\/span>]<\/span> charArray =<\/span> input.<\/span>toCharArray<\/span>(<\/span>)<\/span>;<\/span>\r\n\t\r\n\tfor<\/span> (<\/span>char<\/span> c :<\/span> charArray)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>!<\/span>Character<\/span>.<\/span>isWhitespace<\/span>(<\/span>c)<\/span>)<\/span>\r\n\t\t\toutput.<\/span>append<\/span>(<\/span>c)<\/span>;<\/span>\r\n\t}<\/span>\r\n\t\r\n\treturn<\/span> output.<\/span>toString<\/span>(<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
Java\u3067\u6587\u5b57\u5217\u304b\u3089\u30b9\u30da\u30fc\u30b9\u3084\u4ed6\u306e\u6587\u5b57\u3092\u53d6\u308a\u9664\u304f\u65b9\u6cd5\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
9. Java \u3067\u6587\u5b57\u5217\u304b\u3089\u524d\u5f8c\u306e\u30b9\u30da\u30fc\u30b9\u3092\u53d6\u308a\u9664\u304f\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f<\/h2>\n
\u65e5\u672c\u8a9e\u3067\u4e00\u3064\u306e\u30aa\u30d7\u30b7\u30e7\u30f3\u3067\u4ee5\u4e0b\u3092\u8a00\u3044\u63db\u3048\u307e\u3059\uff1a<\/p>\n
String\u30af\u30e9\u30b9\u306b\u306f\u3001\u5148\u982d\u3068\u672b\u5c3e\u306e\u7a7a\u767d\u3092\u524a\u9664\u3059\u308b\u305f\u3081\u306e2\u3064\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308a\u307e\u3059: trim()\u3068strip()\u3002strip()\u30e1\u30bd\u30c3\u30c9\u306fJava 11\u3067String\u30af\u30e9\u30b9\u306b\u8ffd\u52a0\u3055\u308c\u307e\u3057\u305f\u3002strip()\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6587\u5b57\u304c\u7a7a\u767d\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306bCharacter.isWhitespace()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u307e\u3059\u3002\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306fUnicode\u30b3\u30fc\u30c9\u30dd\u30a4\u30f3\u30c8\u3092\u4f7f\u7528\u3057\u307e\u3059\u304c\u3001trim()\u30e1\u30bd\u30c3\u30c9\u306f\u30b3\u30fc\u30c9\u30dd\u30a4\u30f3\u30c8\u5024\u304cU+0020\u4ee5\u4e0b\u306e\u4efb\u610f\u306e\u6587\u5b57\u3092\u7a7a\u767d\u6587\u5b57\u3068\u3057\u3066\u8a8d\u8b58\u3057\u307e\u3059\u3002<\/p>\n
strip()\u30e1\u30bd\u30c3\u30c9\u306f\u3001Unicode\u6a19\u6e96\u3092\u4f7f\u7528\u3057\u3066\u7a7a\u767d\u3092\u524a\u9664\u3059\u308b\u305f\u3081\u306e\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5\u3067\u3059\u3002\u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u4f8b\u306f\u3001strip()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u7a7a\u767d\u3092\u524a\u9664\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
String<\/span> s =<\/span> \"  abc  def\\t\"<\/span>;<\/span>\r\n\t\t\r\ns =<\/span> s.<\/span>strip<\/span>(<\/span>)<\/span>;<\/span>\r\n\t\t\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s)<\/span>;<\/span>\r\n<\/code><\/pre>\n
\u6587\u5b57\u5217\u306f\u30a4\u30df\u30e5\u30fc\u30bf\u30d6\u30eb\uff08\u5909\u66f4\u4e0d\u53ef\u80fd\uff09\u306a\u306e\u3067\u3001strip()\u306e\u7d50\u679c\u3092\u6587\u5b57\u5217\u306b\u5272\u308a\u5f53\u3066\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n
10. Java\u3067\u914d\u5217\u3092\u30bd\u30fc\u30c8\u3059\u308b\u65b9\u6cd5\u306f\u306a\u3093\u3067\u3059\u304b\uff1f<\/h2>\n
Arrays\u30e6\u30fc\u30c6\u30a3\u30ea\u30c6\u30a3\u30af\u30e9\u30b9\u306b\u306f\u3001\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u914d\u5217\u3068\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u914d\u5217\u306e\u4e21\u65b9\u3092\u30bd\u30fc\u30c8\u3059\u308b\u305f\u3081\u306e\u591a\u91cd\u5b9a\u7fa9\u3055\u308c\u305fsort()\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308a\u307e\u3059\u3002\u3082\u3057\u81ea\u7136\u306a\u9806\u5e8f\u3067\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u914d\u5217\u3092\u30bd\u30fc\u30c8\u3057\u305f\u3044\u5834\u5408\u306f\u3001\u4ee5\u4e0b\u306e\u4f8b\u306b\u793a\u3059\u3088\u3046\u306b\u3001Arrays.sort()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
int<\/span>[<\/span>]<\/span> array =<\/span> {<\/span>1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>,<\/span> -<\/span>1<\/span>,<\/span> -<\/span>2<\/span>,<\/span> 4<\/span>}<\/span>;<\/span>\r\n\r\nArrays<\/span>.<\/span>sort<\/span>(<\/span>array)<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>Arrays<\/span>.<\/span>toString<\/span>(<\/span>array)<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
\u3057\u304b\u3057\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u914d\u5217\u3092\u30bd\u30fc\u30c8\u3057\u305f\u3044\u5834\u5408\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cComparable\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u30bd\u30fc\u30c8\u57fa\u6e96\u3092\u6307\u5b9a\u3057\u305f\u3044\u5834\u5408\u306f\u3001\u30bd\u30fc\u30c8\u30ed\u30b8\u30c3\u30af\u306bComparator\u3092\u6e21\u3059\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002Java\u306eComparable\u3068Comparator\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
11. Java\u3067\u30d7\u30ed\u30b0\u30e9\u30e0\u4e0a\u3067\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u30b7\u30ca\u30ea\u30aa\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f<\/h2>\n
\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u3068\u306f\u3001\u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u306eJava\u74b0\u5883\u3067\u30012\u3064\u4ee5\u4e0a\u306e\u30b9\u30ec\u30c3\u30c9\u304c\u6c38\u9060\u306b\u30d6\u30ed\u30c3\u30af\u3055\u308c\u3066\u3057\u307e\u3046\u72b6\u6cc1\u3092\u6307\u3057\u307e\u3059\u3002\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u306e\u72b6\u6cc1\u306f\u30012\u3064\u4ee5\u4e0a\u306e\u30b9\u30ec\u30c3\u30c9\u304c\u3084\u308a\u53d6\u308a\u3092\u884c\u3046\u5834\u5408\u306b\u767a\u751f\u3057\u307e\u3059\u3002\u6b21\u306e\u30b3\u30fc\u30c9\u4f8b\u3067\u306f\u3001\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u306e\u72b6\u6cc1\u3092\u4f5c\u308a\u51fa\u3057\u307e\u3059\u3002<\/p>\n
public<\/span> class<\/span> ThreadDeadlock<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> throws<\/span> InterruptedException<\/span> {<\/span>\r\n        Object<\/span> obj1 =<\/span> new<\/span> Object<\/span>(<\/span>)<\/span>;<\/span>\r\n        Object<\/span> obj2 =<\/span> new<\/span> Object<\/span>(<\/span>)<\/span>;<\/span>\r\n        Object<\/span> obj3 =<\/span> new<\/span> Object<\/span>(<\/span>)<\/span>;<\/span>\r\n    \r\n        Thread<\/span> t1 =<\/span> new<\/span> Thread<\/span>(<\/span>new<\/span> SyncThread<\/span>(<\/span>obj1,<\/span> obj2)<\/span>,<\/span> \"t1\"<\/span>)<\/span>;<\/span>\r\n        Thread<\/span> t2 =<\/span> new<\/span> Thread<\/span>(<\/span>new<\/span> SyncThread<\/span>(<\/span>obj2,<\/span> obj3)<\/span>,<\/span> \"t2\"<\/span>)<\/span>;<\/span>\r\n        Thread<\/span> t3 =<\/span> new<\/span> Thread<\/span>(<\/span>new<\/span> SyncThread<\/span>(<\/span>obj3,<\/span> obj1)<\/span>,<\/span> \"t3\"<\/span>)<\/span>;<\/span>\r\n        \r\n        t1.<\/span>start<\/span>(<\/span>)<\/span>;<\/span>\r\n        Thread<\/span>.<\/span>sleep<\/span>(<\/span>5000<\/span>)<\/span>;<\/span>\r\n        t2.<\/span>start<\/span>(<\/span>)<\/span>;<\/span>\r\n        Thread<\/span>.<\/span>sleep<\/span>(<\/span>5000<\/span>)<\/span>;<\/span>\r\n        t3.<\/span>start<\/span>(<\/span>)<\/span>;<\/span>        \r\n    }<\/span>\r\n\r\n}<\/span>\r\n\r\nclass<\/span> SyncThread<\/span> implements<\/span> Runnable<\/span> {<\/span>\r\n\r\n    private<\/span> Object<\/span> obj1;<\/span>\r\n    private<\/span> Object<\/span> obj2;<\/span>\r\n\r\n    public<\/span> SyncThread<\/span>(<\/span>Object<\/span> o1,<\/span> Object<\/span> o2)<\/span> {<\/span>\r\n        this<\/span>.<\/span>obj1 =<\/span> o1;<\/span>\r\n        this<\/span>.<\/span>obj2 =<\/span> o2;<\/span>\r\n    }<\/span>\r\n\r\n    @Override<\/span>\r\n    public<\/span> void<\/span> run<\/span>(<\/span>)<\/span> {<\/span>\r\n        String<\/span> name =<\/span> Thread<\/span>.<\/span>currentThread<\/span>(<\/span>)<\/span>.<\/span>getName<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" acquiring lock on \"<\/span> +<\/span> obj1)<\/span>;<\/span>\r\n        synchronized<\/span> (<\/span>obj1)<\/span> {<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" acquired lock on \"<\/span> +<\/span> obj1)<\/span>;<\/span>\r\n            work<\/span>(<\/span>)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" acquiring lock on \"<\/span> +<\/span> obj2)<\/span>;<\/span>\r\n            synchronized<\/span> (<\/span>obj2)<\/span> {<\/span>\r\n                System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" acquired lock on \"<\/span> +<\/span> obj2)<\/span>;<\/span>\r\n                work<\/span>(<\/span>)<\/span>;<\/span>\r\n            }<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" released lock on \"<\/span> +<\/span> obj2)<\/span>;<\/span>\r\n        }<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" released lock on \"<\/span> +<\/span> obj1)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>name +<\/span> \" finished execution.\"<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n\r\n    private<\/span> void<\/span> work<\/span>(<\/span>)<\/span> {<\/span>\r\n        try<\/span> {<\/span>\r\n            Thread<\/span>.<\/span>sleep<\/span>(<\/span>30000<\/span>)<\/span>;<\/span>\r\n        }<\/span> catch<\/span> (<\/span>InterruptedException<\/span> e)<\/span> {<\/span>\r\n            e.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>\r\n        }<\/span>\r\n    }<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
\u4ee5\u4e0b\u306e\u6587\u3092\u65e5\u672c\u8a9e\u3067\u4e00\u3064\u306e\u30aa\u30d7\u30b7\u30e7\u30f3\u3067\u8a00\u3044\u63db\u3048\u307e\u3059\uff1a
\n\u6700\u521d\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30ed\u30c3\u30af\u30923\u3064\u306e\u30b9\u30ec\u30c3\u30c9\u3059\u3079\u3066\u304c\u53d6\u5f97\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u5f7c\u3089\u306f\u5171\u6709\u30ea\u30bd\u30fc\u30b9\u3092\u4f7f\u7528\u3057\u3001\u4e8c\u3064\u76ee\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30ed\u30c3\u30af\u3092\u7121\u671f\u9650\u306b\u5f85\u3061\u7d9a\u3051\u308b\u3088\u3046\u306b\u958b\u59cb\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u3092\u691c\u51fa\u3059\u308b\u305f\u3081\u306bJava\u30b9\u30ec\u30c3\u30c9\u30c0\u30f3\u30d7\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002Java\u3067\u306e\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
12. Java\u3067\u6574\u6570\u306e\u968e\u4e57\u3092\u6c42\u3081\u308b\u65b9\u6cd5\u306f\u3069\u306e\u3088\u3046\u306a\u3082\u306e\u3067\u3059\u304b\uff1f<\/h2>\n
\u6574\u6570\u306e\u968e\u4e57\u306f\u3001\u4e0e\u3048\u3089\u308c\u305f\u6570\u304b\u30891\u307e\u3067\u306e\u3059\u3079\u3066\u306e\u6570\u3092\u639b\u3051\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u8a08\u7b97\u3055\u308c\u307e\u3059\u3002<\/p>\n
F(n) = F(1)*F(2)...F(n-1)*F(n)\r\n<\/code><\/pre>\n
\u4ee5\u4e0b\u306e\u4f8b\u984c\u30b3\u30fc\u30c9\u306f\u3001\u6574\u6570\u306e\u968e\u4e57\u3092\u518d\u5e30\u3092\u4f7f\u3063\u3066\u6c42\u3081\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
public<\/span> static<\/span> long<\/span> factorial<\/span>(<\/span>long<\/span> n)<\/span> {<\/span>\r\n\tif<\/span> (<\/span>n ==<\/span> 1<\/span>)<\/span>\r\n\t\treturn<\/span> 1<\/span>;<\/span>\r\n\telse<\/span>\r\n\t\treturn<\/span> (<\/span>n *<\/span> factorial<\/span>(<\/span>n -<\/span> 1<\/span>)<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
13. Java\u3067\u30ea\u30f3\u30af\u30ea\u30b9\u30c8\u3092\u9006\u306b\u3059\u308b\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f (Java de rinkurisuto o gyaku ni suru h\u014dh\u014d wa nan desu ka?)<\/h2>\n
LinkedList\u306edescendingIterator()\u306f\u3001\u8981\u7d20\u3092\u9006\u306e\u9806\u5e8f\u3067\u53cd\u5fa9\u3059\u308b\u30a4\u30c6\u30ec\u30fc\u30bf\u3092\u8fd4\u3057\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001\u3053\u306e\u30a4\u30c6\u30ec\u30fc\u30bf\u3092\u4f7f\u7528\u3057\u3066\u8981\u7d20\u304c\u9006\u9806\u306b\u30ea\u30b9\u30c8\u3055\u308c\u305f\u65b0\u3057\u3044LinkedList\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
LinkedList<\/span><<\/span>Integer<\/span>><\/span><\/span> ll =<\/span> new<\/span> LinkedList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nll.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\nll.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\nll.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>ll)<\/span>;<\/span>\r\n\r\nLinkedList<\/span><<\/span>Integer<\/span>><\/span><\/span> ll1 =<\/span> new<\/span> LinkedList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nll.<\/span>descendingIterator<\/span>(<\/span>)<\/span>.<\/span>forEachRemaining<\/span>(<\/span>ll1::<\/span>add<\/span>)<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>ll1)<\/span>;<\/span>\r\n<\/code><\/pre>\n
\u30c7\u30fc\u30bf\u69cb\u9020\u3068\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u306e\u89b3\u70b9\u304b\u3089\u3001\u9023\u7d50\u30ea\u30b9\u30c8\u306e\u9006\u8ee2\u306b\u3064\u3044\u3066\u3082\u3063\u3068\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
14. Java\u30672\u5206\u63a2\u7d22\u3092\u5b9f\u88c5\u3059\u308b\u65b9\u6cd5\u306f\u3069\u3046\u3067\u3059\u304b\uff1f (Java de nibun tansaku o jissh\u014d suru h\u014dh\u014d wa d\u014d desu ka?)<\/h2>\n
\u914d\u5217\u306e\u8981\u7d20\u306f\u3001\u30d0\u30a4\u30ca\u30ea\u30b5\u30fc\u30c1\u3092\u5b9f\u88c5\u3059\u308b\u305f\u3081\u306b\u30bd\u30fc\u30c8\u3055\u308c\u3066\u3044\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u30d0\u30a4\u30ca\u30ea\u30b5\u30fc\u30c1\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u306f\u4ee5\u4e0b\u306e\u6761\u4ef6\u306b\u57fa\u3065\u3044\u3066\u3044\u307e\u3059\u3002<\/p>\n
    \n
  • If the key is less than the middle element, then you now need to search only in the first half of the array.<\/li>\n
  • If the key is greater than the middle element, then you need to search only in the second half of the array.<\/li>\n
  • If the key is equal to the middle element in the array, then the search ends.<\/li>\n
  • Finally, if the key is not found in the whole array, then it should return -1. This indicates that the element is not present.<\/li>\n<\/ul>\n
    \u6b21\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001\u4e8c\u5206\u63a2\u7d22\u3092\u5b9f\u88c5\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    public<\/span> static<\/span> int<\/span> binarySearch<\/span>(<\/span>int<\/span> arr[<\/span>]<\/span>,<\/span> int<\/span> low,<\/span> int<\/span> high,<\/span> int<\/span> key)<\/span> {<\/span>\r\n\tint<\/span> mid =<\/span> (<\/span>low +<\/span> high)<\/span> \/<\/span> 2<\/span>;<\/span>\r\n\r\n\twhile<\/span> (<\/span>low <=<\/span> high)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>arr[<\/span>mid]<\/span> <<\/span> key)<\/span> {<\/span>\r\n\t\t\tlow =<\/span> mid +<\/span> 1<\/span>;<\/span>\r\n\t\t}<\/span> else<\/span> if<\/span> (<\/span>arr[<\/span>mid]<\/span> ==<\/span> key)<\/span> {<\/span>\r\n\t\t\treturn<\/span> mid;<\/span>\r\n\t\t}<\/span> else<\/span> {<\/span>\r\n\t\t\thigh =<\/span> mid -<\/span> 1<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t\tmid =<\/span> (<\/span>low +<\/span> high)<\/span> \/<\/span> 2<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\tif<\/span> (<\/span>low ><\/span> high)<\/span> {<\/span>\r\n\t\treturn<\/span> -<\/span>1<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\treturn<\/span> -<\/span>1<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    15. \u30de\u30fc\u30b8\u30bd\u30fc\u30c8\u3092\u793a\u3059Java\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
    \u30de\u30fc\u30b8\u30bd\u30fc\u30c8\u306f\u6700\u3082\u52b9\u7387\u7684\u306a\u30bd\u30fc\u30c8\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u306e\u4e00\u3064\u3067\u3059\u3002\u300c\u5206\u5272\u7d71\u6cbb\u6cd5\u300d\u306e\u539f\u7406\u306b\u57fa\u3065\u3044\u3066\u3044\u307e\u3059\u3002\u30ea\u30b9\u30c8\u3092\u8907\u6570\u306e\u30b5\u30d6\u30ea\u30b9\u30c8\u306b\u5206\u5272\u3057\u3001\u305d\u308c\u305e\u308c\u306e\u30b5\u30d6\u30ea\u30b9\u30c8\u304c\u5358\u4e00\u306e\u8981\u7d20\u304b\u3089\u6210\u308b\u3088\u3046\u306b\u3057\u307e\u3059\u3002\u305d\u3057\u3066\u3001\u305d\u308c\u3089\u306e\u30b5\u30d6\u30ea\u30b9\u30c8\u3092\u7d71\u5408\u3059\u308b\u3053\u3068\u3067\u30bd\u30fc\u30c8\u3055\u308c\u305f\u30ea\u30b9\u30c8\u3092\u5f97\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u306f\u3001\u30de\u30fc\u30b8\u30bd\u30fc\u30c8\u3092\u4f7f\u3046\u65b9\u6cd5\u306e\u4e00\u3064\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    public<\/span> class<\/span> MergeSort<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tint<\/span>[<\/span>]<\/span> arr =<\/span> {<\/span> 70<\/span>,<\/span> 50<\/span>,<\/span> 30<\/span>,<\/span> 10<\/span>,<\/span> 20<\/span>,<\/span> 40<\/span>,<\/span> 60<\/span> }<\/span>;<\/span>\r\n\r\n\t\tint<\/span>[<\/span>]<\/span> merged =<\/span> mergeSort<\/span>(<\/span>arr,<\/span> 0<\/span>,<\/span> arr.<\/span>length -<\/span> 1<\/span>)<\/span>;<\/span>\r\n\r\n\t\tfor<\/span> (<\/span>int<\/span> val :<\/span> merged)<\/span> {<\/span>\r\n\t\t\tSystem<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>val +<\/span> \" \"<\/span>)<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> int<\/span>[<\/span>]<\/span> mergeTwoSortedArrays<\/span>(<\/span>int<\/span>[<\/span>]<\/span> one,<\/span> int<\/span>[<\/span>]<\/span> two)<\/span> {<\/span>\r\n\t\tint<\/span>[<\/span>]<\/span> sorted =<\/span> new<\/span> int<\/span>[<\/span>one.<\/span>length +<\/span> two.<\/span>length]<\/span>;<\/span>\r\n\r\n\t\tint<\/span> i =<\/span> 0<\/span>;<\/span>\r\n\t\tint<\/span> j =<\/span> 0<\/span>;<\/span>\r\n\t\tint<\/span> k =<\/span> 0<\/span>;<\/span>\r\n\r\n\t\twhile<\/span> (<\/span>i <<\/span> one.<\/span>length &&<\/span> j <<\/span> two.<\/span>length)<\/span> {<\/span>\r\n\t\t\tif<\/span> (<\/span>one[<\/span>i]<\/span> <<\/span> two[<\/span>j]<\/span>)<\/span> {<\/span>\r\n\t\t\t\tsorted[<\/span>k]<\/span> =<\/span> one[<\/span>i]<\/span>;<\/span>\r\n\t\t\t\tk++<\/span>;<\/span>\r\n\t\t\t\ti++<\/span>;<\/span>\r\n\t\t\t}<\/span> else<\/span> {<\/span>\r\n\t\t\t\tsorted[<\/span>k]<\/span> =<\/span> two[<\/span>j]<\/span>;<\/span>\r\n\t\t\t\tk++<\/span>;<\/span>\r\n\t\t\t\tj++<\/span>;<\/span>\r\n\t\t\t}<\/span>\r\n\t\t}<\/span>\r\n\r\n\t\tif<\/span> (<\/span>i ==<\/span> one.<\/span>length)<\/span> {<\/span>\r\n\t\t\twhile<\/span> (<\/span>j <<\/span> two.<\/span>length)<\/span> {<\/span>\r\n\t\t\t\tsorted[<\/span>k]<\/span> =<\/span> two[<\/span>j]<\/span>;<\/span>\r\n\t\t\t\tk++<\/span>;<\/span>\r\n\t\t\t\tj++<\/span>;<\/span>\r\n\t\t\t}<\/span>\r\n\t\t}<\/span>\r\n\r\n\t\tif<\/span> (<\/span>j ==<\/span> two.<\/span>length)<\/span> {<\/span>\r\n\t\t\twhile<\/span> (<\/span>i <<\/span> one.<\/span>length)<\/span> {<\/span>\r\n\t\t\t\tsorted[<\/span>k]<\/span> =<\/span> one[<\/span>i]<\/span>;<\/span>\r\n\t\t\t\tk++<\/span>;<\/span>\r\n\t\t\t\ti++<\/span>;<\/span>\r\n\t\t\t}<\/span>\r\n\t\t}<\/span>\r\n\r\n\t\treturn<\/span> sorted;<\/span>\r\n\t}<\/span>\r\n\r\n\tpublic<\/span> static<\/span> int<\/span>[<\/span>]<\/span> mergeSort<\/span>(<\/span>int<\/span>[<\/span>]<\/span> arr,<\/span> int<\/span> lo,<\/span> int<\/span> hi)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>lo ==<\/span> hi)<\/span> {<\/span>\r\n\t\t\tint<\/span>[<\/span>]<\/span> br =<\/span> new<\/span> int<\/span>[<\/span>1<\/span>]<\/span>;<\/span>\r\n\t\t\tbr[<\/span>0<\/span>]<\/span> =<\/span> arr[<\/span>lo]<\/span>;<\/span>\r\n\r\n\t\t\treturn<\/span> br;<\/span>\r\n\t\t}<\/span>\r\n\r\n\t\tint<\/span> mid =<\/span> (<\/span>lo +<\/span> hi)<\/span> \/<\/span> 2<\/span>;<\/span>\r\n\r\n\t\tint<\/span>[<\/span>]<\/span> fh =<\/span> mergeSort<\/span>(<\/span>arr,<\/span> lo,<\/span> mid)<\/span>;<\/span>\r\n\t\tint<\/span>[<\/span>]<\/span> sh =<\/span> mergeSort<\/span>(<\/span>arr,<\/span> mid +<\/span> 1<\/span>,<\/span> hi)<\/span>;<\/span>\r\n\r\n\t\tint<\/span>[<\/span>]<\/span> merged =<\/span> mergeTwoSortedArrays<\/span>(<\/span>fh,<\/span> sh)<\/span>;<\/span>\r\n\r\n\t\treturn<\/span> merged;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
    16. Java\u3067\u6587\u5b57\u306e\u30d4\u30e9\u30df\u30c3\u30c9\u3092\u4f5c\u6210\u3067\u304d\u307e\u3059\u304b\uff1f<\/h2>\n
    \u30d1\u30bf\u30fc\u30f3\u30d7\u30ed\u30b0\u30e9\u30e0\u306f\u975e\u5e38\u306b\u4eba\u6c17\u306e\u3042\u308b\u9762\u63a5\u306e\u30c8\u30d4\u30c3\u30af\u3067\u3059\u3002\u3053\u306e\u30bf\u30a4\u30d7\u306e\u8cea\u554f\u306f\u3001\u9762\u63a5\u8005\u306e\u8ad6\u7406\u7684\u601d\u8003\u80fd\u529b\u3092\u7406\u89e3\u3059\u308b\u305f\u3081\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002\u3055\u307e\u3056\u307e\u306a\u65b9\u6cd5\u3067\u30d4\u30e9\u30df\u30c3\u30c9\u30d1\u30bf\u30fc\u30f3\u3092\u4f5c\u6210\u3059\u308b\u4f8b\u306b\u3064\u3044\u3066\u306f\u3001Java\u306e\u30d4\u30e9\u30df\u30c3\u30c9\u30d1\u30bf\u30fc\u30f3\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
    \uff11\uff17\uff0e\u540c\u3058\u8981\u7d20\u3092\u542b\u3080\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308bJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
    2\u3064\u306e\u914d\u5217\u304c\u540c\u3058\u8981\u7d20\u3092\u542b\u3093\u3067\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b\u306b\u306f\u3001\u307e\u305a\u3001\u4e21\u65b9\u306e\u914d\u5217\u304b\u3089\u8981\u7d20\u306e\u30bb\u30c3\u30c8\u3092\u4f5c\u6210\u3057\u3001\u305d\u308c\u304b\u3089\u3053\u308c\u3089\u306e\u30bb\u30c3\u30c8\u5185\u306e\u8981\u7d20\u3092\u6bd4\u8f03\u3057\u3066\u3001\u4e21\u65b9\u306e\u30bb\u30c3\u30c8\u306b\u5b58\u5728\u3057\u306a\u3044\u8981\u7d20\u304c\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u898b\u3064\u3051\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u6b21\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u30012\u3064\u306e\u914d\u5217\u304c\u5171\u901a\u306e\u8981\u7d20\u306e\u307f\u3092\u542b\u3093\u3067\u3044\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    import<\/span> java.<\/span>util.<\/span><\/span>Arrays<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>HashSet<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>Set<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> ArraySameElements<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tInteger<\/span>[<\/span>]<\/span> a1 =<\/span> {<\/span>1<\/span>,<\/span>2<\/span>,<\/span>3<\/span>,<\/span>2<\/span>,<\/span>1<\/span>}<\/span>;<\/span>\r\n\t\tInteger<\/span>[<\/span>]<\/span> a2 =<\/span> {<\/span>1<\/span>,<\/span>2<\/span>,<\/span>3<\/span>}<\/span>;<\/span>\r\n\t\tInteger<\/span>[<\/span>]<\/span> a3 =<\/span> {<\/span>1<\/span>,<\/span>2<\/span>,<\/span>3<\/span>,<\/span>4<\/span>}<\/span>;<\/span>\r\n\t\t\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>sameElements<\/span>(<\/span>a1,<\/span> a2)<\/span>)<\/span>;<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>sameElements<\/span>(<\/span>a1,<\/span> a3)<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\tstatic<\/span> boolean<\/span> sameElements<\/span>(<\/span>Object<\/span>[<\/span>]<\/span> array1,<\/span> Object<\/span>[<\/span>]<\/span> array2)<\/span> {<\/span>\r\n\t\tSet<\/span><<\/span>Object<\/span>><\/span><\/span> uniqueElements1 =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>Arrays<\/span>.<\/span>asList<\/span>(<\/span>array1)<\/span>)<\/span>;<\/span>\r\n\t\tSet<\/span><<\/span>Object<\/span>><\/span><\/span> uniqueElements2 =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>Arrays<\/span>.<\/span>asList<\/span>(<\/span>array2)<\/span>)<\/span>;<\/span>\r\n\t\t\r\n\t\t\/\/ if size is different, means there will be a mismatch<\/span>\r\n\t\tif<\/span> (<\/span>uniqueElements1.<\/span>size<\/span>(<\/span>)<\/span> !=<\/span> uniqueElements2.<\/span>size<\/span>(<\/span>)<\/span>)<\/span> return<\/span> false<\/span>;<\/span>\r\n\t\t\r\n\t\tfor<\/span> (<\/span>Object<\/span> obj :<\/span> uniqueElements1)<\/span> {<\/span>\r\n\t\t\t\/\/ element not present in both?<\/span>\r\n\t\t\tif<\/span> (<\/span>!<\/span>uniqueElements2.<\/span>contains<\/span>(<\/span>obj)<\/span>)<\/span> return<\/span> false<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t\t\r\n\t\treturn<\/span> true<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
    <\/code><\/pre>\n
    Output<\/div>\n
    <\/code><\/pre>\n
    true false<\/p>\n
    <\/code><\/pre>\n
    18. Java\u3067\u6574\u6570\u306e\u914d\u5217\u306e\u8981\u7d20\u306e\u5408\u8a08\u3092\u7b97\u51fa\u3059\u308b\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f<\/h2>\n
    \u914d\u5217\u8981\u7d20\u3092\u7e70\u308a\u8fd4\u3057\u51e6\u7406\u3057\u3001\u5408\u8a08\u3092\u53d6\u5f97\u3059\u308b\u305f\u3081\u306b\u3001for\u30eb\u30fc\u30d7\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
    int<\/span>[<\/span>]<\/span> array =<\/span> {<\/span> 1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>,<\/span> 4<\/span>,<\/span> 5<\/span> }<\/span>;<\/span>\r\n\r\nint<\/span> sum =<\/span> 0<\/span>;<\/span>\r\n\r\nfor<\/span> (<\/span>int<\/span> i :<\/span> array)<\/span>\r\n\tsum +=<\/span> i;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>sum)<\/span>;<\/span>\r\n<\/code><\/pre>\n
    19. Java\u3067\u914d\u5217\u5185\u306e2\u756a\u76ee\u306b\u5927\u304d\u3044\u6570\u3092\u898b\u3064\u3051\u308b\u65b9\u6cd5\u306f\u3069\u3046\u3067\u3059\u304b\uff1f<\/h2>\n
    \u3053\u306e\u554f\u984c\u3092\u89e3\u6c7a\u3059\u308b\u305f\u3081\u306b\u306f\u69d8\u3005\u306a\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002\u914d\u5217\u3092\u81ea\u7136\u306a\u6607\u9806\u3067\u6574\u5217\u3055\u305b\u30012\u756a\u76ee\u306b\u5927\u304d\u3044\u5024\u3092\u53d6\u308b\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002\u305f\u3060\u3057\u3001\u6574\u5217\u306f\u30b3\u30b9\u30c8\u304c\u304b\u304b\u308a\u307e\u3059\u3002\u307e\u305f\u3001\u6b21\u306e\u4f8b\u306b\u793a\u3059\u3088\u3046\u306b\u3001\u5358\u4e00\u306e\u7e70\u308a\u8fd4\u3057\u30672\u756a\u76ee\u306b\u5927\u304d\u3044\u5024\u3092\u898b\u3064\u3051\u308b\u305f\u3081\u306b2\u3064\u306e\u5909\u6570\u3092\u4f7f\u7528\u3059\u308b\u65b9\u6cd5\u3082\u3042\u308a\u307e\u3059\u3002<\/p>\n
    private<\/span> static<\/span> int<\/span> findSecondHighest<\/span>(<\/span>int<\/span>[<\/span>]<\/span> array)<\/span> {<\/span>\r\n\tint<\/span> highest =<\/span> Integer<\/span>.<\/span>MIN_VALUE<\/span>;<\/span>\r\n\tint<\/span> secondHighest =<\/span> Integer<\/span>.<\/span>MIN_VALUE<\/span>;<\/span>\r\n\r\n\tfor<\/span> (<\/span>int<\/span> i :<\/span> array)<\/span> {<\/span>\r\n\t\tif<\/span> (<\/span>i ><\/span> highest)<\/span> {<\/span>\r\n\t\t\tsecondHighest =<\/span> highest;<\/span>\r\n\t\t\thighest =<\/span> i;<\/span>\r\n\t\t}<\/span> else<\/span> if<\/span> (<\/span>i ><\/span> secondHighest)<\/span> {<\/span>\r\n\t\t\tsecondHighest =<\/span> i;<\/span>\r\n\t\t}<\/span>\r\n\r\n\t}<\/span>\r\n\treturn<\/span> secondHighest;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    20. Java\u3067\u914d\u5217\u3092\u30b7\u30e3\u30c3\u30d5\u30eb\u3059\u308b\u306b\u306f\u3069\u3046\u3059\u308c\u3070\u3044\u3044\u3067\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u306f\u3001\u30e9\u30f3\u30c0\u30e0\u306a\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u756a\u53f7\u3092\u751f\u6210\u3057\u3001\u8981\u7d20\u3092\u30b7\u30e3\u30c3\u30d5\u30eb\u3059\u308b\u305f\u3081\u306bRandom\u30af\u30e9\u30b9\u3092\u4f7f\u7528\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    int<\/span>[<\/span>]<\/span> array =<\/span> {<\/span> 1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>,<\/span> 4<\/span>,<\/span> 5<\/span>,<\/span> 6<\/span>,<\/span> 7<\/span> }<\/span>;<\/span>\r\n\r\nRandom<\/span> rand =<\/span> new<\/span> Random<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nfor<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> array.<\/span>length;<\/span> i++<\/span>)<\/span> {<\/span>\r\n\tint<\/span> randomIndexToSwap =<\/span> rand.<\/span>nextInt<\/span>(<\/span>array.<\/span>length)<\/span>;<\/span>\r\n\tint<\/span> temp =<\/span> array[<\/span>randomIndexToSwap]<\/span>;<\/span>\r\n\tarray[<\/span>randomIndexToSwap]<\/span> =<\/span> array[<\/span>i]<\/span>;<\/span>\r\n\tarray[<\/span>i]<\/span> =<\/span> temp;<\/span>\r\n}<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>Arrays<\/span>.<\/span>toString<\/span>(<\/span>array)<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
    \u8907\u6570\u306e\u30e9\u30a6\u30f3\u30c9\u3092\u30b7\u30e3\u30c3\u30d5\u30eb\u3059\u308b\u305f\u3081\u306b\u3001\u5225\u306efor\u30eb\u30fc\u30d7\u5185\u3067\u30b7\u30e3\u30c3\u30d5\u30eb\u30b3\u30fc\u30c9\u3092\u5b9f\u884c\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
    21. Java\u3067\u30c6\u30ad\u30b9\u30c8\u30d5\u30a1\u30a4\u30eb\u5185\u306e\u6587\u5b57\u5217\u3092\u898b\u3064\u3051\u308b\u65b9\u6cd5\u306f\u3069\u306e\u3088\u3046\u306b\u3057\u307e\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u4f8b\u984c\u30b3\u30fc\u30c9\u306f\u3001Scanner\u30af\u30e9\u30b9\u3092\u4f7f\u7528\u3057\u3066\u30d5\u30a1\u30a4\u30eb\u306e\u5185\u5bb9\u3092\u884c\u5358\u4f4d\u3067\u8aad\u307f\u8fbc\u307f\u3001\u305d\u306e\u5f8c\u3001String\u306econtains()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u6587\u5b57\u5217\u304c\u30d5\u30a1\u30a4\u30eb\u5185\u306b\u5b58\u5728\u3059\u308b\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    boolean<\/span> findStringInFile<\/span>(<\/span>String<\/span> filePath,<\/span> String<\/span> str)<\/span> throws<\/span> FileNotFoundException<\/span> {<\/span>\r\n\tFile<\/span> file =<\/span> new<\/span> File<\/span>(<\/span>filePath)<\/span>;<\/span>\r\n\r\n\tScanner<\/span> scanner =<\/span> new<\/span> Scanner<\/span>(<\/span>file)<\/span>;<\/span>\r\n\r\n\t\/\/ read the file line by line<\/span>\r\n\twhile<\/span> (<\/span>scanner.<\/span>hasNextLine<\/span>(<\/span>)<\/span>)<\/span> {<\/span>\r\n\t\tString<\/span> line =<\/span> scanner.<\/span>nextLine<\/span>(<\/span>)<\/span>;<\/span>\r\n\t\tif<\/span> (<\/span>line.<\/span>contains<\/span>(<\/span>str)<\/span>)<\/span> {<\/span>\r\n\t\t\tscanner.<\/span>close<\/span>(<\/span>)<\/span>;<\/span>\r\n\t\t\treturn<\/span> true<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t}<\/span>\r\n\tscanner.<\/span>close<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\treturn<\/span> false<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    \u6ce8\u610f\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u5185\u3067\u691c\u7d22\u3059\u308b\u6587\u5b57\u5217\u306b\u6539\u884c\u6587\u5b57\u304c\u542b\u307e\u308c\u3066\u3044\u306a\u3044\u3053\u3068\u3092\u524d\u63d0\u3068\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    22. Java\u3067\u7279\u5b9a\u306e\u5f62\u5f0f\u3067\u65e5\u4ed8\u3092\u5370\u5237\u3059\u308b\u306b\u306f\u3069\u3046\u3059\u308c\u3070\u3088\u3044\u3067\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u4f8b\u3067\u306f\u3001SimpleDateFormat\u30af\u30e9\u30b9\u3092\u4f7f\u7528\u3057\u3066\u65e5\u4ed8\u6587\u5b57\u5217\u3092\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3059\u308b\u65b9\u6cd5\u304c\u793a\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n
    String<\/span> pattern =<\/span> \"MM-dd-yyyy\"<\/span>;<\/span>\r\nSimpleDateFormat<\/span> simpleDateFormat =<\/span> new<\/span> SimpleDateFormat<\/span>(<\/span>pattern)<\/span>;<\/span>\r\n\r\nString<\/span> date =<\/span> simpleDateFormat.<\/span>format<\/span>(<\/span>new<\/span> Date<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>date)<\/span>;<\/span> \/\/ 06-23-2020<\/span>\r\n<\/code><\/pre>\n
    Java\u306eSimpleDateFormat\u306b\u3064\u3044\u3066\u3082\u3063\u3068\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
    23. Java\u30672\u3064\u306e\u30ea\u30b9\u30c8\u3092\u30de\u30fc\u30b8\u3059\u308b\u65b9\u6cd5\u306f\u3069\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u4f8b\u306f\u3001Java\u3067\u8907\u6570\u306e\u30ea\u30b9\u30c8\u3092\u30de\u30fc\u30b8\u3059\u308b\u305f\u3081\u306baddAll()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    List<\/span><<\/span>String<\/span>><\/span><\/span> list1 =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\nlist1.<\/span>add<\/span>(<\/span>\"1\"<\/span>)<\/span>;<\/span>\r\nList<\/span><<\/span>String<\/span>><\/span><\/span> list2 =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\nlist2.<\/span>add<\/span>(<\/span>\"2\"<\/span>)<\/span>;<\/span>\r\n\r\nList<\/span><<\/span>String<\/span>><\/span><\/span> mergedList =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>list1)<\/span>;<\/span>\r\nmergedList.<\/span>addAll<\/span>(<\/span>list2)<\/span>;<\/span>\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>mergedList)<\/span>;<\/span> \/\/ [1, 2]<\/span>\r\n<\/code><\/pre>\n
    24. \u5024\u3067HashMap\u3092\u30bd\u30fc\u30c8\u3059\u308bJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
    HashMap\u306f\u9806\u5e8f\u4ed8\u3051\u3089\u308c\u305f\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u4ee5\u4e0b\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u5024\u306b\u57fa\u3065\u3044\u3066\u30a8\u30f3\u30c8\u30ea\u30fc\u3092\u30bd\u30fc\u30c8\u3057\u3001\u633f\u5165\u306e\u9806\u5e8f\u3092\u7dad\u6301\u3059\u308bLinkedHashMap\u306b\u683c\u7d0d\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    import<\/span> java.<\/span>util.<\/span><\/span>ArrayList<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>HashMap<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>LinkedHashMap<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>List<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>Map<\/span>.<\/span>Entry<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span><\/span>Set<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> SortHashMapByValue<\/span> {<\/span>\r\n\r\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tMap<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span><\/span> scores =<\/span> new<\/span> HashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\t\tscores.<\/span>put<\/span>(<\/span>\"David\"<\/span>,<\/span> 95<\/span>)<\/span>;<\/span>\r\n\t\tscores.<\/span>put<\/span>(<\/span>\"Jane\"<\/span>,<\/span> 80<\/span>)<\/span>;<\/span>\r\n\t\tscores.<\/span>put<\/span>(<\/span>\"Mary\"<\/span>,<\/span> 97<\/span>)<\/span>;<\/span>\r\n\t\tscores.<\/span>put<\/span>(<\/span>\"Lisa\"<\/span>,<\/span> 78<\/span>)<\/span>;<\/span>\r\n\t\tscores.<\/span>put<\/span>(<\/span>\"Dino\"<\/span>,<\/span> 65<\/span>)<\/span>;<\/span>\r\n\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>scores)<\/span>;<\/span>\r\n\r\n\t\tscores =<\/span> sortByValue<\/span>(<\/span>scores)<\/span>;<\/span>\r\n\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>scores)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\tprivate<\/span> static<\/span> Map<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span><\/span> sortByValue<\/span>(<\/span>Map<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span><\/span> scores)<\/span> {<\/span>\r\n\t\tMap<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span><\/span> sortedByValue =<\/span> new<\/span> LinkedHashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\t\t\/\/ get the entry set<\/span>\r\n\t\tSet<\/span><<\/span>Entry<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span>><\/span><\/span> entrySet =<\/span> scores.<\/span>entrySet<\/span>(<\/span>)<\/span>;<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>entrySet)<\/span>;<\/span>\r\n\r\n\t\t\/\/ create a list since the set is unordered<\/span>\r\n\t\tList<\/span><<\/span>Entry<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span>><\/span><\/span> entryList =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>entrySet)<\/span>;<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>entryList)<\/span>;<\/span>\r\n\r\n\t\t\/\/ sort the list by value<\/span>\r\n\t\tentryList.<\/span>sort<\/span>(<\/span>(<\/span>x,<\/span> y)<\/span> -><\/span> x.<\/span>getValue<\/span>(<\/span>)<\/span>.<\/span>compareTo<\/span>(<\/span>y.<\/span>getValue<\/span>(<\/span>)<\/span>)<\/span>)<\/span>;<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>entryList)<\/span>;<\/span>\r\n\r\n\t\t\/\/ populate the new hash map<\/span>\r\n\t\tfor<\/span> (<\/span>Entry<\/span><<\/span>String<\/span>,<\/span> Integer<\/span>><\/span><\/span> e :<\/span> entryList)<\/span>\r\n\t\t\tsortedByValue.<\/span>put<\/span>(<\/span>e.<\/span>getKey<\/span>(<\/span>)<\/span>,<\/span> e.<\/span>getValue<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n\r\n\t\treturn<\/span> sortedByValue;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
    25. Java\u3067\u5165\u529b\u3055\u308c\u305f\u6587\u5b57\u5217\u304b\u3089\u6307\u5b9a\u3055\u308c\u305f\u6587\u5b57\u306e\u3059\u3079\u3066\u306e\u51fa\u73fe\u3092\u524a\u9664\u3059\u308b\u306b\u306f\u3001\u3069\u3046\u3059\u308c\u3070\u3088\u3044\u3067\u3059\u304b\uff1f<\/h2>\n
    String\u30af\u30e9\u30b9\u306b\u306f\u6587\u5b57\u3092\u524a\u9664\u3059\u308b\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308a\u307e\u305b\u3093\u3002\u6b21\u306e\u4f8b\u30b3\u30fc\u30c9\u3067\u306f\u3001replace()\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u6307\u5b9a\u3055\u308c\u305f\u6587\u5b57\u306e\u306a\u3044\u65b0\u3057\u3044\u6587\u5b57\u5217\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    String<\/span> str1 =<\/span> \"abcdABCDabcdABCD\"<\/span>;<\/span>\r\n\t\t\r\nstr1 =<\/span> str1.<\/span>replace<\/span>(<\/span>\"a\"<\/span>,<\/span> \"\"<\/span>)<\/span>;<\/span> \r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>str1)<\/span>;<\/span> \/\/ bcdABCDbcdABCD<\/span>\r\n<\/code><\/pre>\n
    Java\u3067\u306f\u3001\u6587\u5b57\u5217\u306f\u5909\u66f4\u4e0d\u53ef\u80fd\u3067\u3059\u3002\u3059\u3079\u3066\u306e\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9\u306f\u65b0\u3057\u3044\u6587\u5b57\u5217\u3092\u8fd4\u3057\u3001\u305d\u308c\u3092\u5225\u306e\u5909\u6570\u306b\u5272\u308a\u5f53\u3066\u308b\u5fc5\u8981\u304c\u3042\u308b\u305f\u3081\u3067\u3059\u3002Java\u3067\u6587\u5b57\u5217\u304b\u3089\u6587\u5b57\u3092\u524a\u9664\u3059\u308b\u65b9\u6cd5\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
    \u300cJava\u3067\u6587\u5b57\u5217\u5185\u306e\u7570\u306a\u308b\u6587\u5b57\u3068\u305d\u306e\u500b\u6570\u3092\u53d6\u5f97\u3059\u308b\u306b\u306f\u3001\u3069\u306e\u3088\u3046\u306b\u3059\u308c\u3070\u826f\u3044\u3067\u3059\u304b\uff1f\u300d<\/h2>\n
    \u6587\u5b57\u5217\u304b\u3089\u6587\u5b57\u306e\u914d\u5217\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u305d\u308c\u304b\u3089\u3001\u305d\u308c\u3092\u7e70\u308a\u8fd4\u3057\u51e6\u7406\u3057\u3001\u6587\u5b57\u3092\u30ad\u30fc\u3068\u305d\u306e\u6570\u3092\u5024\u3068\u3059\u308bHashMap\u3092\u4f5c\u6210\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u6587\u5b57\u5217\u306e\u6587\u5b57\u3092\u62bd\u51fa\u3057\u3066\u6570\u3048\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    String<\/span> str1 =<\/span> \"abcdABCDabcd\"<\/span>;<\/span>\r\n\r\nchar<\/span>[<\/span>]<\/span> chars =<\/span> str1.<\/span>toCharArray<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nMap<\/span><<\/span>Character<\/span>,<\/span> Integer<\/span>><\/span><\/span> charsCount =<\/span> new<\/span> HashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nfor<\/span> (<\/span>char<\/span> c :<\/span> chars)<\/span> {<\/span>\r\n\tif<\/span> (<\/span>charsCount.<\/span>containsKey<\/span>(<\/span>c)<\/span>)<\/span> {<\/span>\r\n\t\tcharsCount.<\/span>put<\/span>(<\/span>c,<\/span> charsCount.<\/span>get<\/span>(<\/span>c)<\/span> +<\/span> 1<\/span>)<\/span>;<\/span>\r\n\t}<\/span> else<\/span>\r\n\t\tcharsCount.<\/span>put<\/span>(<\/span>c,<\/span> 1<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>charsCount)<\/span>;<\/span> \/\/ {a=2, A=1, b=2, B=1, c=2, C=1, d=2, D=1}<\/span>\r\n<\/code><\/pre>\n
    27. Java\u306b\u304a\u3044\u3066\u3001String\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u30d7\u30ed\u30b0\u30e9\u30e0\u4e0a\u3067\u5909\u66f4\u4e0d\u53ef\u80fd\u3067\u3042\u308b\u3053\u3068\u3092\u8a3c\u660e\u3067\u304d\u307e\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001String\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u4e0d\u5909\u3067\u3042\u308b\u3053\u3068\u3092\u8a3c\u660e\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002\u30b3\u30fc\u30c9\u5185\u306e\u30b3\u30e1\u30f3\u30c8\u306f\u5404\u30b9\u30c6\u30c3\u30d7\u3092\u8aac\u660e\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    String<\/span> s1 =<\/span> \"Java\"<\/span>;<\/span> \/\/ \"Java\" String created in pool and reference assigned to s1<\/span>\r\n\r\nString<\/span> s2 =<\/span> s1;<\/span> \/\/s2 also has the same reference to \"Java\" in the pool<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s1 ==<\/span> s2)<\/span>;<\/span> \/\/ proof that s1 and s2 have the same reference<\/span>\r\n\r\ns1 =<\/span> \"Python\"<\/span>;<\/span> \r\n\/\/s1 value got changed above, so how String is immutable?<\/span>\r\n\r\n\/\/in the above case a new String \"Python\" got created in the pool<\/span>\r\n\/\/s1 is now referring to the new String in the pool <\/span>\r\n\/\/BUT, the original String \"Java\" is still unchanged and remains in the pool<\/span>\r\n\/\/s2 is still referring to the original String \"Java\" in the pool<\/span>\r\n\r\n\/\/ proof that s1 and s2 have different reference<\/span>\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s1 ==<\/span> s2)<\/span>;<\/span> \r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s2)<\/span>;<\/span> \r\n\/\/ prints \"Java\" supporting the fact that original String value is unchanged, hence String is immutable<\/span>\r\n<\/code><\/pre>\n
    28. Java\u3067\u7d99\u627f\u3092\u793a\u3059\u305f\u3081\u306e\u3044\u304f\u3064\u304b\u306e\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u306f\u3001extends\u30ad\u30fc\u30ef\u30fc\u30c9\u3092\u4f7f\u7528\u3057\u3066Animal\u30af\u30e9\u30b9\u306e\u30b5\u30d6\u30af\u30e9\u30b9\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002\u65b0\u3057\u3044Cat\u30af\u30e9\u30b9\u306f\u3001Animal\u30af\u30e9\u30b9\u304b\u3089\u5909\u6570\u3092\u7d99\u627f\u3057\u3001Cat\u30af\u30e9\u30b9\u306b\u306e\u307f\u5c5e\u3059\u308b\u8ffd\u52a0\u306e\u30b3\u30fc\u30c9\u3092\u8ffd\u52a0\u3057\u307e\u3059\u3002<\/p>\n
    class<\/span> Animal<\/span> {<\/span>\r\n\tString<\/span> color;<\/span>\r\n}<\/span>\r\n\r\nclass<\/span> Cat<\/span> extends<\/span> Animal<\/span> {<\/span>\r\n\tvoid<\/span> meow<\/span>(<\/span>)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"Meow\"<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    29. Java\u306b\u304a\u3044\u3066\u3001\u591a\u91cd\u7d99\u627f\u306b\u3088\u308b\u30c0\u30a4\u30e4\u30e2\u30f3\u30c9\u554f\u984c\u3092\u3069\u306e\u3088\u3046\u306b\u793a\u3057\u307e\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u3088\u3046\u306b\u65e5\u672c\u8a9e\u3067\u8a00\u3044\u63db\u3048\u307e\u3059\u3002\u4e00\u3064\u306e\u30aa\u30d7\u30b7\u30e7\u30f3\u3067\u826f\u3044\u3067\u3059\u3002<\/p>\n
    \u30c0\u30a4\u30e4\u30e2\u30f3\u30c9\u554f\u984c\u306f\u3001\u3042\u308b\u30af\u30e9\u30b9\u304c\u8907\u6570\u306e\u30af\u30e9\u30b9\u304b\u3089\u7d99\u627f\u3055\u308c\u308b\u5834\u5408\u306b\u767a\u751f\u3057\u3001\u3069\u306e\u30af\u30e9\u30b9\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u5b9f\u884c\u3059\u308b\u304b\u304c\u660e\u78ba\u3067\u306a\u3044\u5834\u5408\u306b\u66d6\u6627\u6027\u304c\u751f\u3058\u307e\u3059\u3002Java\u3067\u306f\u3001\u4ee5\u4e0b\u306e\u4f8b\u3067\u793a\u3055\u308c\u308b\u30c0\u30a4\u30e4\u30e2\u30f3\u30c9\u554f\u984c\u3092\u907f\u3051\u308b\u305f\u3081\u306b\u3001\u8907\u6570\u306e\u30af\u30e9\u30b9\u306e\u62e1\u5f35\u3092\u8a31\u53ef\u3057\u307e\u305b\u3093\u3002<\/p>\n
    interface<\/span> I<\/span> {<\/span>\r\n\tvoid<\/span> foo<\/span>(<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\nclass<\/span> A<\/span> implements<\/span> I<\/span> {<\/span>\r\n\tpublic<\/span> void<\/span> foo<\/span>(<\/span>)<\/span> {<\/span>}<\/span>\r\n}<\/span>\r\n\r\nclass<\/span> B<\/span> implements<\/span> I<\/span> {<\/span>\r\n\tpublic<\/span> void<\/span> foo<\/span>(<\/span>)<\/span> {<\/span>}<\/span>\r\n}<\/span>\r\n\r\nclass<\/span> C<\/span> extends<\/span> A<\/span>,<\/span> B<\/span> {<\/span> \/\/ won't compile<\/span>\r\n\tpublic<\/span> void<\/span> bar<\/span>(<\/span>)<\/span> {<\/span>\r\n\t\tsuper<\/span>.<\/span>foo<\/span>(<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    30. Java\u3067\u306etry-catch\u306e\u4f8b\u3092\u3069\u306e\u3088\u3046\u306b\u8aac\u660e\u3057\u307e\u3059\u304b\uff1f<\/h2>\n
    \u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u306f\u3001try-catch\u306e\u4f8b\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    try<\/span> {<\/span>\r\n\tFileInputStream<\/span> fis =<\/span> new<\/span> FileInputStream<\/span>(<\/span>\"test.txt\"<\/span>)<\/span>;<\/span>\r\n}<\/span> catch<\/span>(<\/span>FileNotFoundException<\/span> e)<\/span> {<\/span>\r\n\te.<\/span>printStackTrace<\/span>(<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    Java 7\u4ee5\u964d\u3067\u306f\u3001\u6b21\u306e\u4f8b\u306b\u793a\u3059\u3088\u3046\u306b\u30011\u3064\u306ecatch\u30d6\u30ed\u30c3\u30af\u3067\u8907\u6570\u306e\u4f8b\u5916\u3092\u30ad\u30e3\u30c3\u30c1\u3059\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u3002\u5168\u3066\u306ecatch\u30d6\u30ed\u30c3\u30af\u306b\u540c\u3058\u30b3\u30fc\u30c9\u304c\u3042\u308b\u5834\u5408\u306b\u4fbf\u5229\u3067\u3059\u3002<\/p>\n
    public<\/span> static<\/span> void<\/span> foo<\/span>(<\/span>int<\/span> x)<\/span> throws<\/span> IllegalArgumentException<\/span>,<\/span> NullPointerException<\/span> {<\/span>\r\n\t\/\/ some code<\/span>\r\n}<\/span>\r\n\r\npublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\ttry<\/span> {<\/span>\r\n\t\tfoo<\/span>(<\/span>10<\/span>)<\/span>;<\/span>\r\n\t}<\/span> catch<\/span> (<\/span>IllegalArgumentException<\/span> |<\/span> NullPointerException<\/span> e)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    31. NullPointerException\u3092\u8868\u793a\u3059\u308b\u305f\u3081\u306eJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u66f8\u3044\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
    \u3082\u3057\u30cc\u30eb\u306b\u5bfe\u3057\u3066\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u5834\u5408\u3001\u4ee5\u4e0b\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u3067\u306fNullPointerException\u304c\u30b9\u30ed\u30fc\u3055\u308c\u307e\u3059\u3002<\/p>\n
    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\tprintString<\/span>(<\/span>null<\/span>,<\/span> 3<\/span>)<\/span>;<\/span>\r\n\t\r\n}<\/span>\r\n\r\nstatic<\/span> void<\/span> printString<\/span>(<\/span>String<\/span> s,<\/span> int<\/span> count)<\/span> {<\/span>\r\n\tfor<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> count;<\/span> i++<\/span>)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s.<\/span>toUpperCase<\/span>(<\/span>)<\/span>)<\/span>;<\/span> \/\/ Exception in thread \"main\" java.lang.NullPointerException<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    \u4ee5\u4e0b\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306b\u793a\u3055\u308c\u3066\u3044\u308b\u3088\u3046\u306b\u3001\u65e9\u671f\u306e\u691c\u8a3c\u306e\u305f\u3081\u306b\u30cc\u30eb\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046\u3079\u304d\u3067\u3059\u3002<\/p>\n
    static<\/span> void<\/span> printString<\/span>(<\/span>String<\/span> s,<\/span> int<\/span> count)<\/span> {<\/span>\r\n\tif<\/span> (<\/span>s ==<\/span> null<\/span>)<\/span> return<\/span>;<\/span>\r\n\tfor<\/span> (<\/span>int<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> count;<\/span> i++<\/span>)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s.<\/span>toUpperCase<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    \u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u8981\u4ef6\u306b\u57fa\u3065\u3044\u3066\u3001IllegalArgumentException\u3092\u6295\u3052\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u3002<\/p>\n
    32. Java\u3067\u30ec\u30b3\u30fc\u30c9\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u306f\u3069\u306e\u3088\u3046\u306a\u3082\u306e\u3067\u3059\u304b\u3002<\/h2>\n
    Java 16\u3067\u306f\u3001\u30ec\u30b3\u30fc\u30c9\u306f\u6a19\u6e96\u6a5f\u80fd\u3068\u3057\u3066\u8ffd\u52a0\u3055\u308c\u307e\u3057\u305f\u3002\u30ec\u30b3\u30fc\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u6700\u5c0f\u9650\u306e\u30b3\u30fc\u30c9\u3067POJO\u30af\u30e9\u30b9\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u30ec\u30b3\u30fc\u30c9\u306f\u3001hashCode()\u3001equals()\u3001getter\u30e1\u30bd\u30c3\u30c9\u3001\u304a\u3088\u3073toString()\u30e1\u30bd\u30c3\u30c9\u306e\u30b3\u30fc\u30c9\u3092\u81ea\u52d5\u751f\u6210\u3057\u307e\u3059\u3002\u30ec\u30b3\u30fc\u30c9\u306ffinal\u3067\u3042\u308a\u3001\u6697\u9ed9\u7684\u306bjava.lang.Record\u30af\u30e9\u30b9\u3092\u62e1\u5f35\u3057\u307e\u3059\u3002\u6b21\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30ec\u30b3\u30fc\u30c9\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u306e\u4e00\u3064\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    import<\/span> java.<\/span>util.<\/span><\/span>Map<\/span><\/span>;<\/span>\r\n \r\npublic<\/span> record<\/span> EmpRecord<\/span>(<\/span>int<\/span> id,<\/span> String<\/span> name,<\/span> long<\/span> salary,<\/span> Map<\/span><<\/span>String<\/span>,<\/span> String<\/span>><\/span><\/span> addresses)<\/span> {<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
    Java\u306e\u30ec\u30b3\u30fc\u30c9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002POJO\u306b\u95a2\u3059\u308b\u8a73\u7d30\u306b\u3064\u3044\u3066\u306f\u3001Wikipedia\u306e\u300cPlain old Java object\u300d\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
    33. Java\u3067\u30c6\u30ad\u30b9\u30c8\u30d6\u30ed\u30c3\u30af\u3092\u4f5c\u6210\u3059\u308b\u306b\u306f\u3001\u3069\u306e\u3088\u3046\u306b\u3057\u307e\u3059\u304b\uff1f<\/h2>\n
    Java 15\u3067\u306f\u3001\u30c6\u30ad\u30b9\u30c8\u30d6\u30ed\u30c3\u30af\u6a5f\u80fd\u304c\u8ffd\u52a0\u3055\u308c\u307e\u3057\u305f\u3002\u30c6\u30ad\u30b9\u30c8\u30d6\u30ed\u30c3\u30af\u3092\u4f7f\u3063\u3066\u3001\u8907\u6570\u884c\u306e\u6587\u5b57\u5217\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u8907\u6570\u884c\u306e\u6587\u5b57\u5217\u306f\u3001\u4ee5\u4e0b\u306e\u4f8b\u306b\u793a\u3059\u3088\u3046\u306b\u3001\u30c8\u30ea\u30d7\u30eb\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u306e\u30da\u30a2\u306e\u4e2d\u306b\u8a18\u8ff0\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n
    String<\/span> textBlock =<\/span> \"\"\"\r\n\t\tHi\r\n\t\tHello\r\n\t\tYes\"\"\"<\/span>;<\/span>\r\n<\/code><\/pre>\n
    \u300cHi\\\\nHello\\\\nYes\u300d\u3068\u3044\u3046\u3088\u3046\u306a\u6587\u5b57\u5217\u3092\u4f5c\u6210\u3059\u308b\u306e\u3068\u540c\u3058\u3067\u3059\u3002<\/p>\n
    34. Java\u3067\u306e\u30b9\u30a4\u30c3\u30c1\u5f0f\u3068\u8907\u6570\u30e9\u30d9\u30eb\u306e\u30b1\u30fc\u30b9\u30b9\u30c6\u30fc\u30c8\u30e1\u30f3\u30c8\u306e\u4f8b\u3092\u793a\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
    \u30b9\u30a4\u30c3\u30c1\u5f0f\u306fJava 14\u3067\u6a19\u6e96\u7684\u306a\u6a5f\u80fd\u3068\u3057\u3066\u8ffd\u52a0\u3055\u308c\u307e\u3057\u305f\u3002\u4ee5\u4e0b\u306e\u4f8b\u3067\u306f\u3001\u30b9\u30a4\u30c3\u30c1\u5f0f\u3068\u8907\u6570\u306e\u30e9\u30d9\u30eb\u4ed8\u304d\u30b1\u30fc\u30b9\u6587\u304c\u793a\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n
    int<\/span> choice =<\/span> 2<\/span>;<\/span>\r\n\r\nint<\/span> x =<\/span> switch<\/span> (<\/span>choice)<\/span> {<\/span>\r\n    case<\/span> 1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>:<\/span>\r\n\t    yield<\/span> choice;<\/span>\r\n    default<\/span>:<\/span>\r\n\t    yield<\/span> -<\/span>1<\/span>;<\/span>\r\n}<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"x = \"<\/span> +<\/span> x)<\/span>;<\/span> \/\/ x = 2<\/span>\r\n<\/code><\/pre>\n
    \u30b9\u30a4\u30c3\u30c1\u5f0f\u3067\u3082\u3001\u30e9\u30e0\u30c0\u5f0f\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
    String<\/span> day =<\/span> \"TH\"<\/span>;<\/span>\r\nString<\/span> result =<\/span> switch<\/span> (<\/span>day)<\/span> {<\/span>\r\n    case<\/span> \"M\"<\/span>,<\/span> \"W\"<\/span>,<\/span> \"F\"<\/span> -><\/span> \"MWF\"<\/span>;<\/span>\r\n    case<\/span> \"T\"<\/span>,<\/span> \"TH\"<\/span>,<\/span> \"S\"<\/span> -><\/span> \"TTS\"<\/span>;<\/span>\r\n\r\n    default<\/span> -><\/span> {<\/span>\r\n\t    if<\/span> (<\/span>day.<\/span>isEmpty<\/span>(<\/span>)<\/span>)<\/span>\r\n\t\t    yield<\/span> \"Please insert a valid day.\"<\/span>;<\/span>\r\n\t    else<\/span>\r\n\t\t    yield<\/span> \"Looks like a Sunday.\"<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>result)<\/span>;<\/span> \/\/ TTH<\/span>\r\n<\/code><\/pre>\n
    35. \u30b3\u30de\u30f3\u30c9\u30e9\u30a4\u30f3\u304b\u3089Java\u30af\u30e9\u30b9\u3092\u30b3\u30f3\u30d1\u30a4\u30eb\u3057\u3066\u5b9f\u884c\u3059\u308b\u306b\u306f\u3001\u3069\u306e\u3088\u3046\u306b\u3057\u307e\u3059\u304b\uff1f<\/h2>\n
    \u3053\u306e\u4f8b\u306f\u3001\u4ee5\u4e0b\u306eJava\u30d5\u30a1\u30a4\u30eb\u306b\u8a00\u53ca\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
    public<\/span> class<\/span> Test<\/span> {<\/span>\r\n\r\npublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span> args[<\/span>]<\/span>)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"Hi\"<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
    \u3042\u306a\u305f\u306e\u30bf\u30fc\u30df\u30ca\u30eb\u3067\u4ee5\u4e0b\u306e\u30b3\u30de\u30f3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u3001\u305d\u308c\u3092\u30b3\u30f3\u30d1\u30a4\u30eb\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
    <\/code><\/pre>\n
      \n
    1. javac Test.java<\/li>\n<\/ol>\n
      <\/code><\/pre>\n
       <\/p>\n
      <\/code><\/pre>\n
      \u30af\u30e9\u30b9\u3092\u5b9f\u884c\u3059\u308b\u306b\u306f\u3001\u30bf\u30fc\u30df\u30ca\u30eb\u3067\u4ee5\u4e0b\u306e\u30b3\u30de\u30f3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
      <\/code><\/pre>\n
        \n
      1. java<\/span> Test<\/li>\n<\/ol>\n
        <\/code><\/pre>\n
         <\/p>\n
        <\/code><\/pre>\n
        \u6700\u65b0\u306e\u30ea\u30ea\u30fc\u30b9\u3067\u306f\u3001\u30af\u30e9\u30b9\u30d5\u30a1\u30a4\u30eb\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u3067\u3082\u3001java\u30b3\u30de\u30f3\u30c9\u306f\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u30b3\u30f3\u30d1\u30a4\u30eb\u3057\u307e\u3059\u3002\u30af\u30e9\u30b9\u304ccom.example\u306e\u3088\u3046\u306a\u30d1\u30c3\u30b1\u30fc\u30b8\u306b\u3042\u308b\u5834\u5408\u3001\u305d\u308c\u306fcom\/example\u3068\u3044\u3046\u30d5\u30a9\u30eb\u30c0\u5185\u306b\u3042\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u30b3\u30f3\u30d1\u30a4\u30eb\u3068\u5b9f\u884c\u3059\u308b\u30b3\u30de\u30f3\u30c9\u306f\u6b21\u306e\u901a\u308a\u3067\u3059\uff1a<\/p>\n
        <\/code><\/pre>\n
          \n
        1. java<\/span> com\/example\/Test.java<\/li>\n<\/ol>\n
          <\/code><\/pre>\n
           <\/p>\n
          <\/code><\/pre>\n
          \u30af\u30e9\u30b9\u306e\u30b3\u30f3\u30d1\u30a4\u30eb\u3068\u5b9f\u884c\u306b\u8ffd\u52a0\u306eJAR\u30d5\u30a1\u30a4\u30eb\u304c\u5fc5\u8981\u306a\u5834\u5408\u306f\u3001java -cp\u30aa\u30d7\u30b7\u30e7\u30f3\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u4f8b\u3048\u3070\uff1a<\/p>\n
          <\/code><\/pre>\n
            \n
          1. java<\/span> -cp<\/span> .:~\/.m2\/repository\/log4j\/log4j\/1.2.17\/log4j-1.2.17.jar com\/example\/Test.java<\/li>\n<\/ol>\n
            <\/code><\/pre>\n
             <\/p>\n
            <\/code><\/pre>\n
            36. Java\u3067enum\u3092\u4f5c\u6210\u3059\u308b\u306b\u306f\u3001\u3069\u306e\u3088\u3046\u306b\u3057\u307e\u3059\u304b\uff1f<\/h2>\n
            \u4ee5\u4e0b\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001\u57fa\u672c\u7684\u306a\u5217\u6319\u578b\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
            public<\/span> enum<\/span> ThreadStates<\/span> {<\/span>\r\n\tSTART<\/span>,<\/span>\r\n\tRUNNING<\/span>,<\/span>\r\n\tWAITING<\/span>,<\/span>\r\n\tDEAD<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            ThreadStates\u3068\u306f\u3001\u5b9a\u6570\u30d5\u30a3\u30fc\u30eb\u30c9\u3067\u3042\u308bSTART\u3001RUNNING\u3001WAITING\u3001DEAD\u3092\u6301\u3064\u5217\u6319\u578b\u3067\u3059\u3002\u3059\u3079\u3066\u306e\u5217\u6319\u578b\u306f\u3001\u81ea\u52d5\u7684\u306bjava.lang.Enum\u30af\u30e9\u30b9\u3092\u7d99\u627f\u3057\u3001Serializable\u3068Comparable\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3092\u5b9f\u88c5\u3057\u307e\u3059\u3002\u5217\u6319\u578b\u306f\u3001\u30e1\u30bd\u30c3\u30c9\u3092\u6301\u3064\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u3002Java\u3067\u306e\u5217\u6319\u578b\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
            37. Java\u306eforEach()\u30e1\u30bd\u30c3\u30c9\u306f\u3069\u306e\u3088\u3046\u306b\u4f7f\u3044\u307e\u3059\u304b\uff1f<\/h2>\n
            forEach\uff08\uff09\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30a4\u30c6\u30e9\u30d6\u30eb\u306e\u3059\u3079\u3066\u306e\u8981\u7d20\u306b\u30a2\u30af\u30b7\u30e7\u30f3\u3092\u5b9f\u884c\u3059\u308b\u305f\u3081\u306e\u30b7\u30e7\u30fc\u30c8\u30ab\u30c3\u30c8\u3092\u63d0\u4f9b\u3057\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001\u30ea\u30b9\u30c8\u306e\u8981\u7d20\u3092\u7e70\u308a\u8fd4\u3057\u8868\u793a\u3059\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
            List<\/span><<\/span>String<\/span>><\/span><\/span> list =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nIterator<\/span><<\/span>String<\/span>><\/span><\/span> it =<\/span> list.<\/span>iterator<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nwhile<\/span> (<\/span>it.<\/span>hasNext<\/span>(<\/span>)<\/span>)<\/span> {<\/span>\r\n\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>it.<\/span>next<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            \u6b21\u306e\u4f8b\u306e\u3088\u3046\u306b\u3001forEach()\u30e1\u30bd\u30c3\u30c9\u3092\u30e9\u30e0\u30c0\u5f0f\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u30b5\u30a4\u30ba\u3092\u7e2e\u5c0f\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
            List<\/span><<\/span>String<\/span>><\/span><\/span> list =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\nlist.<\/span>forEach<\/span>(<\/span>System<\/span>.<\/span>out::<\/span>print<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            38. \u30c7\u30d5\u30a9\u30eb\u30c8\u3068\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u3092\u6301\u3064\u30a4\u30f3\u30bf\u30d5\u30a7\u30fc\u30b9\u3092\u3069\u306e\u3088\u3046\u306b\u66f8\u304d\u307e\u3059\u304b\uff1f<\/h2>\n
            Java 8\u3067\u306f\u3001\u30a4\u30f3\u30bf\u30d5\u30a7\u30fc\u30b9\u306b\u30c7\u30d5\u30a9\u30eb\u30c8\u30e1\u30bd\u30c3\u30c9\u3068\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u304c\u5c0e\u5165\u3055\u308c\u307e\u3057\u305f\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u30a4\u30f3\u30bf\u30d5\u30a7\u30fc\u30b9\u3068\u62bd\u8c61\u30af\u30e9\u30b9\u306e\u30ae\u30e3\u30c3\u30d7\u304c\u57cb\u307e\u308a\u307e\u3057\u305f\u3002\u4ee5\u4e0b\u306e\u4f8b\u30b3\u30fc\u30c9\u306f\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u30e1\u30bd\u30c3\u30c9\u3068\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u3092\u6301\u3064\u30a4\u30f3\u30bf\u30d5\u30a7\u30fc\u30b9\u3092\u66f8\u304f\u65b9\u6cd5\u306e\u4e00\u3064\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
            public<\/span> interface<\/span> Interface1<\/span> {<\/span>\r\n\t\r\n\t\/\/ regular abstract method<\/span>\r\n\tvoid<\/span> method1<\/span>(<\/span>String<\/span> str)<\/span>;<\/span>\r\n\t\r\n\tdefault<\/span> void<\/span> log<\/span>(<\/span>String<\/span> str)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"I1 logging::\"<\/span> +<\/span> str)<\/span>;<\/span>\r\n\t}<\/span>\r\n\t\r\n\tstatic<\/span> boolean<\/span> isNull<\/span>(<\/span>String<\/span> str)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"Interface Null Check\"<\/span>)<\/span>;<\/span>\r\n\r\n\t\treturn<\/span> str ==<\/span> null<\/span> ?<\/span> true<\/span> :<\/span> \"\"<\/span>.<\/span>equals<\/span>(<\/span>str)<\/span> ?<\/span> true<\/span> :<\/span> false<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
            \u300cJava 8\u306e\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u306e\u5909\u66f4\u3067\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u30e1\u30bd\u30c3\u30c9\u3068\u30b9\u30bf\u30c6\u30a3\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u5b66\u3073\u307e\u3057\u3087\u3046\u3002\u300d<\/p>\n
            39. \u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3092\u4f5c\u6210\u3059\u308b\u65b9\u6cd5\u306f\u4f55\u3067\u3059\u304b\uff1f(Kanshugata int\u0101f\u0113su o sakusei suru h\u014dh\u014d wa nan desu ka?)<\/h2>\n
            \u305f\u3060\uff11\u3064\u306e\u62bd\u8c61\u30e1\u30bd\u30c3\u30c9\u3092\u6301\u3064\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u306f\u3001\u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3068\u547c\u3070\u308c\u307e\u3059\u3002\u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u306e\u4e3b\u306a\u5229\u70b9\u306f\u3001\u30e9\u30e0\u30c0\u5f0f\u3092\u4f7f\u7528\u3057\u3066\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u5316\u3067\u304d\u308b\u305f\u3081\u3001\u5927\u304d\u306a\u533f\u540d\u30af\u30e9\u30b9\u306e\u5b9f\u88c5\u3092\u907f\u3051\u308b\u3053\u3068\u304c\u3067\u304d\u308b\u3053\u3068\u3067\u3059\u3002@FunctionalInterface\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306f\u3001\u6b21\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306b\u793a\u3055\u308c\u3066\u3044\u308b\u3088\u3046\u306b\u3001\u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3092\u793a\u3057\u307e\u3059\u3002<\/p>\n
            @FunctionalInterface<\/span>\r\ninterface<\/span> Foo<\/span> {<\/span>\r\n\tvoid<\/span> test<\/span>(<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            40. Java\u3067\u30e9\u30e0\u30c0\u5f0f\u3092\u4f7f\u7528\u3057\u305f\u4f8b\u3092\u793a\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
            \u30e9\u30f3\u30ca\u30d6\u30eb\u306f\u3001\u95a2\u6570\u578b\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u306e\u512a\u308c\u305f\u4f8b\u3067\u3059\u3002\u6b21\u306e\u30b3\u30fc\u30c9\u306e\u4f8b\u306b\u793a\u3059\u3088\u3046\u306b\u3001\u30e9\u30f3\u30d0\u30c0\u5f0f\u3092\u4f7f\u7528\u3057\u3066\u30e9\u30f3\u30ca\u30d6\u30eb\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
            Runnable<\/span> r1 =<\/span> (<\/span>)<\/span> -><\/span> System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"My Runnable\"<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            41. Java\u3067\u306e\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3068\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u306e\u4f8b\u3092\u793a\u3057\u3066\u304f\u3060\u3055\u3044\u3002 (Java de no overroado to overraido no rei o shimeshite kudasai.)<\/h2>\n
            \u540c\u3058\u540d\u524d\u3092\u6301\u3064\uff12\u3064\u4ee5\u4e0a\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u30af\u30e9\u30b9\u306b\u3042\u308b\u5834\u5408\u3001\u305d\u308c\u3089\u306f\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u3068\u547c\u3070\u308c\u307e\u3059\u3002\u6b21\u306e\u4f8b\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9print\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
            class<\/span> Foo<\/span> {<\/span>\r\n\tvoid<\/span> print<\/span>(<\/span>String<\/span> s)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s)<\/span>;<\/span>\r\n\t}<\/span>\r\n\r\n\tvoid<\/span> print<\/span>(<\/span>String<\/span> s,<\/span> int<\/span> count)<\/span> {<\/span>\r\n\t\twhile<\/span> (<\/span>count ><\/span> 0<\/span>)<\/span> {<\/span>\r\n\t\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s)<\/span>;<\/span>\r\n\t\t\tcount--<\/span>;<\/span>\r\n\t\t}<\/span>\r\n\t}<\/span>\r\n\r\n}<\/span>\r\n<\/code><\/pre>\n
            \u89aa\u30af\u30e9\u30b9\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u5b50\u30af\u30e9\u30b9\u3067\u3082\u5b9f\u88c5\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u3001\u305d\u308c\u306f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3068\u547c\u3070\u308c\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u4f8b\u3067\u306f\u3001\u4e21\u30af\u30e9\u30b9\u306b\u5b9f\u88c5\u3055\u308c\u3066\u3044\u308bprintname()\u30e1\u30bd\u30c3\u30c9\u306b\u6ce8\u91c8\u3092\u4ed8\u3051\u308b\u65b9\u6cd5\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n
            class<\/span> Base<\/span> {<\/span>\r\n\tvoid<\/span> printName<\/span>(<\/span>)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"Base Class\"<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n\r\nclass<\/span> Child<\/span> extends<\/span> Base<\/span> {<\/span>\r\n\t@Override<\/span>\r\n\tvoid<\/span> printName<\/span>(<\/span>)<\/span> {<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"Child Class\"<\/span>)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            Java\u306b\u304a\u3051\u308b\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3068\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u306b\u3064\u3044\u3066\u3082\u3063\u3068\u5b66\u3073\u307e\u3057\u3087\u3046\u3002<\/p>\n
            42. What do you think the output will be?
            \n\u51fa\u529b\u306f\u3069\u3046\u306a\u308b\u304b\u3001\u4f55\u304b\u4e88\u60f3\u306f\u3042\u308b\uff1f<\/h2>\n
            43. Can you guess what the output would look like?
            \n\u51fa\u529b\u306f\u3069\u3046\u3044\u3046\u98a8\u306b\u306a\u308b\u3068\u601d\u3044\u307e\u3059\u304b\uff1f<\/p>\n
            44. Take a guess at the expected output.
            \n\u4e88\u6e2c\u3055\u308c\u308b\u51fa\u529b\u3092\u63a8\u6e2c\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
            45. Do you have an idea of what the output will be?
            \n\u51fa\u529b\u306e\u4e88\u60f3\u306f\u3042\u308a\u307e\u3059\u304b\uff1f<\/p>\n
            46. Give it a shot and predict the output.
            \n\u30c1\u30e3\u30ec\u30f3\u30b8\u3057\u3066\u3001\u51fa\u529b\u3092\u4e88\u6e2c\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
            47. Make an educated guess about the output.
            \n\u51fa\u529b\u306b\u3064\u3044\u3066\u6559\u990a\u306e\u3042\u308b\u4e88\u60f3\u3092\u7acb\u3066\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
            48. Could you hazard a guess as to what the output might be?
            \n\u51fa\u529b\u306f\u3069\u306e\u3088\u3046\u306a\u3082\u306e\u306b\u306a\u308b\u304b\u3001\u63a8\u6e2c\u3057\u3066\u307f\u3066\u3044\u305f\u3060\u3051\u307e\u3059\u304b\uff1f<\/p>\n
            49. Take a stab at what you think the output will be.
            \n\u51fa\u529b\u304c\u3069\u3046\u306a\u308b\u304b\u3001\u4e88\u6e2c\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
            \u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u30b9\u30cb\u30da\u30c3\u30c8\u306e\u51fa\u529b\u3092\u4e88\u6e2c\u3057\u3066\u3001\u81ea\u5206\u81ea\u8eab\u3092\u30c6\u30b9\u30c8\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
            \n
            String<\/span> s1 =<\/span> \"abc\"<\/span>;<\/span>\r\nString<\/span> s2 =<\/span> \"abc\"<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"s1 == s2 is:\"<\/span> +<\/span> s1 ==<\/span> s2)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \n\u507d\u4e0e\u3048\u3089\u308c\u305f\u6587\u306e\u51fa\u529b\u306f\u507d\u3067\u3059\u3002\u306a\u305c\u306a\u3089\u3001\uff0b\u6f14\u7b97\u5b50\u306f\uff1d\uff1d\u6f14\u7b97\u5b50\u3088\u308a\u3082\u512a\u5148\u5ea6\u304c\u9ad8\u3044\u304b\u3089\u3067\u3059\u3002\u305d\u306e\u305f\u3081\u3001\u4e0e\u3048\u3089\u308c\u305f\u5f0f\u306f\u300cs1 == s2 is:abc\u300d\u3068\u300cabc\u300d\u3068\u3044\u3046\u5024\u3092\u6bd4\u8f03\u3057\u305f\u7d50\u679c\u3001\u300c\u507d\u300d\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/details>\n
            \n
            String<\/span> s3 =<\/span> \"JournalDev\"<\/span>;<\/span>\r\nint<\/span> start =<\/span> 1<\/span>;<\/span>\r\nchar<\/span> end =<\/span> 5<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s3.<\/span>substring<\/span>(<\/span>start,<\/span> end)<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \nourn\u4e0e\u3048\u3089\u308c\u305f\u30b9\u30c6\u30fc\u30c8\u30e1\u30f3\u30c8\u306e\u51fa\u529b\u306fourn\u3067\u3059\u3002\u6700\u521d\u306e\u6587\u5b57\u306f\u81ea\u52d5\u7684\u306bint\u578b\u306b\u30ad\u30e3\u30b9\u30c8\u3055\u308c\u307e\u3059\u3002\u305d\u306e\u5f8c\u3001\u6700\u521d\u306e\u6587\u5b57\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u304c0\u3067\u3042\u308b\u305f\u3081\u3001o\u304b\u3089n\u307e\u3067\u5370\u5237\u3055\u308c\u307e\u3059\u3002\u306a\u304a\u3001String\u306esubstring\u30e1\u30bd\u30c3\u30c9\u306f\u3001start\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u304b\u3089end – 1\u306e\u6587\u5b57\u307e\u3067\u3092\u542b\u3080substring\u3092\u4f5c\u6210\u3057\u307e\u3059\u3002<\/p>\n<\/details>\n
            \n
            HashSet<\/span> shortSet =<\/span> new<\/span> HashSet<\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n\tfor<\/span> (<\/span>short<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 100<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>\r\n    shortSet.<\/span>add<\/span>(<\/span>i)<\/span>;<\/span>\r\n    shortSet.<\/span>remove<\/span>(<\/span>i -<\/span> 1<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>shortSet.<\/span>size<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \n100shortSet\u306e\u30b5\u30a4\u30ba\u306f100\u3067\u3059\u3002Java\u306e\u30aa\u30fc\u30c8\u30dc\u30af\u30b7\u30f3\u30b0\u6a5f\u80fd\u306b\u3088\u308a\u3001\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306eshort\u3092\u6301\u3064\u5f0fi\u304cShort\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5909\u63db\u3055\u308c\u307e\u3059\u3002\u540c\u69d8\u306b\u3001\u5f0fi – 1\u306f\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306eint\u3067\u3042\u308a\u3001Integer\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u30aa\u30fc\u30c8\u30dc\u30af\u30b7\u30f3\u30b0\u3055\u308c\u307e\u3059\u3002HashSet\u306bInteger\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u306a\u3044\u305f\u3081\u3001\u4f55\u3082\u524a\u9664\u3055\u308c\u305a\u3001\u30b5\u30a4\u30ba\u306f100\u3067\u3059\u3002<\/p>\n<\/details>\n
            \n
            try<\/span> {<\/span>\r\n\tif<\/span> (<\/span>flag)<\/span> {<\/span>\r\n  \t\twhile<\/span> (<\/span>true<\/span>)<\/span> {<\/span>\r\n   \t\t}<\/span>\r\n   \t}<\/span> else<\/span> {<\/span>\r\n   \t\tSystem<\/span>.<\/span>exit<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n   \t}<\/span>\r\n}<\/span> finally<\/span> {<\/span>\r\n   \tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"In Finally\"<\/span>)<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \n\u51fa\u529b\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u3053\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30d5\u30e9\u30b0\u304ctrue\u306e\u5834\u5408\u306b\u306f\u7121\u9650\u30eb\u30fc\u30d7\u306b\u306a\u308a\u3001\u30d5\u30e9\u30b0\u304cfalse\u306e\u5834\u5408\u306b\u306f\u30d7\u30ed\u30b0\u30e9\u30e0\u304c\u7d42\u4e86\u3057\u307e\u3059\u3002finally\u30d6\u30ed\u30c3\u30af\u306f\u6c7a\u3057\u3066\u5230\u9054\u3055\u308c\u307e\u305b\u3093\u3002<\/details>\n
            \n
            String<\/span> str =<\/span> null<\/span>;<\/span>\r\nString<\/span> str1=<\/span>\"abc\"<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>str1.<\/span>equals<\/span>(<\/span>\"abc\"<\/span>)<\/span> |<\/span> str.<\/span>equals<\/span>(<\/span>null<\/span>)<\/span>)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \n\u4f8b\u5916\u30b9\u30ec\u30c3\u30c9 “main” \u3067 java.lang.NullPointerException \u304c\u767a\u751f\u3057\u307e\u3057\u305f: “” \u304c null \u306a\u306e\u3067 “String.equals(Object)” \u3092\u547c\u3073\u51fa\u3059\u3053\u3068\u304c\u3067\u304d\u307e\u305b\u3093\u3002\u4e0e\u3048\u3089\u308c\u305f\u5370\u5237\u6587\u306f\u3001Java.lang.NullPointerException \u3092\u30b9\u30ed\u30fc\u3057\u307e\u3059\u3002\u306a\u305c\u306a\u3089\u3001OR\u8ad6\u7406\u6f14\u7b97\u5b50\u306f\u4e21\u65b9\u306e\u30ea\u30c6\u30e9\u30eb\u3092\u8a55\u4fa1\u3057\u3066\u304b\u3089\u7d50\u679c\u3092\u8fd4\u3059\u304b\u3089\u3067\u3059\u3002str\u304c null \u306e\u305f\u3081\u3001.equals() \u30e1\u30bd\u30c3\u30c9\u304c\u4f8b\u5916\u3092\u30b9\u30ed\u30fc\u3057\u307e\u3059\u3002\u5e38\u306b\u3001\u5de6\u304b\u3089\u53f3\u306b\u30ea\u30c6\u30e9\u30eb\u5024\u3092\u8a55\u4fa1\u3059\u308b\u30b7\u30e7\u30fc\u30c8\u30b5\u30fc\u30ad\u30c3\u30c8\u8ad6\u7406\u6f14\u7b97\u5b50\u3001\u3064\u307e\u308a || \u3084 && \u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002\u3053\u306e\u5834\u5408\u3001\u6700\u521d\u306e\u30ea\u30c6\u30e9\u30eb\u304c true \u3092\u8fd4\u3059\u305f\u3081\u30012\u756a\u76ee\u306e\u30ea\u30c6\u30e9\u30eb\u306e\u8a55\u4fa1\u306f\u30b9\u30ad\u30c3\u30d7\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/details>\n
            \n
            String<\/span> x =<\/span> \"abc\"<\/span>;<\/span>\r\nString<\/span> y =<\/span> \"abc\"<\/span>;<\/span>\r\n\r\nx.<\/span>concat<\/span>(<\/span>y)<\/span>;<\/span>\r\n\r\nSystem<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>x)<\/span>;<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \nabcx.concat(y) \u306f\u65b0\u3057\u3044\u6587\u5b57\u5217\u3092\u4f5c\u6210\u3057\u307e\u3059\u304c\u3001x \u306b\u5272\u308a\u5f53\u3066\u3089\u308c\u3066\u3044\u306a\u3044\u305f\u3081\u3001x \u306e\u5024\u306f\u5909\u66f4\u3055\u308c\u307e\u305b\u3093\u3002<\/p>\n<\/details>\n
            \n
            public<\/span> class<\/span> MathTest<\/span> {<\/span>\r\n\r\n \tpublic<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>  \t\t\r\n   \t\tint<\/span> x =<\/span> 10<\/span> *<\/span> 10<\/span> -<\/span> 10<\/span>;<\/span>\r\n   \t\t\r\n   \t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>x)<\/span>;<\/span>\r\n   \t}<\/span>\r\n   \r\n}<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \n\u30a8\u30e9\u30fc: \u30af\u30e9\u30b9MathTest\u5185\u306emain\u30e1\u30bd\u30c3\u30c9\u306f\u9759\u7684\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u30e1\u30a4\u30f3\u30e1\u30bd\u30c3\u30c9\u3092\u6b21\u306e\u3088\u3046\u306b\u5b9a\u7fa9\u3057\u3066\u304f\u3060\u3055\u3044:
            \npublic static void main(String[] args)\u6570\u5b66\u6f14\u7b97\u5b50\u306e\u5b9f\u884c\u9806\u5e8f\u306b\u3064\u3044\u3066\u306e\u8cea\u554f\u306e\u3088\u3046\u306b\u601d\u308f\u308c\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u304c\u3001\u3053\u306e\u8cea\u554f\u306f\u5b9f\u969b\u306b\u306fmain\u30e1\u30bd\u30c3\u30c9\u304c\u9759\u7684\u306b\u5ba3\u8a00\u3055\u308c\u3066\u3044\u306a\u304b\u3063\u305f\u3053\u3068\u306b\u6c17\u4ed8\u304f\u3053\u3068\u306b\u95a2\u3057\u3066\u306e\u3082\u306e\u3067\u3059\u3002<\/p>\n<\/details>\n
            \n
            public<\/span> class<\/span> Test<\/span> {<\/span>\r\n   \r\n  \tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n   \t\ttry<\/span> {<\/span>\r\n   \t\t\tthrow<\/span> new<\/span> IOException<\/span>(<\/span>\"Hello\"<\/span>)<\/span>;<\/span>\r\n   \t\t}<\/span> catch<\/span>(<\/span>IOException<\/span> |<\/span> Exception<\/span> e)<\/span> {<\/span>\r\n   \t\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>e.<\/span>getMessage<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n   \t\t}<\/span>\r\n   \t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            \u51fa\u529b
            \nTest.java:5: \u30a8\u30e9\u30fc: \u30b7\u30f3\u30dc\u30eb\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093
            \nthrow new IOException(“Hello”);
            \n^
            \nsymbol: \u30af\u30e9\u30b9 IOException
            \nlocation: \u30af\u30e9\u30b9 Test
            \nTest.java:6: \u30a8\u30e9\u30fc: \u30b7\u30f3\u30dc\u30eb\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093
            \n}catch(IOException | Exception e) {
            \n^
            \nsymbol: \u30af\u30e9\u30b9 IOException
            \nlocation: \u30af\u30e9\u30b9 Test
            \n2\u30a8\u30e9\u30fc\u3053\u306e\u30b3\u30fc\u30c9\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u30a8\u30e9\u30fc\u3092\u5f15\u304d\u8d77\u3053\u3057\u307e\u3059\u3002\u4f8b\u5916IOException\u306f\u4ee3\u66ff\u4f8b\u5916Exception\u306b\u3088\u3063\u3066\u65e2\u306b\u30ad\u30e3\u30c3\u30c1\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/details>\n
            \u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u30b9\u30cb\u30da\u30c3\u30c8\u306b\u306f5\u3064\u306e\u9593\u9055\u3044\u304c\u3042\u308a\u307e\u3059\u3002\u63a2\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/h2>\n
            package<\/span> com.<\/span>digitalocean.<\/span>programming<\/span>-<\/span>interviews;<\/span>\r\n\r\npublic<\/span> class<\/span> String<\/span> Programs<\/span> {<\/span>\r\n\r\n\tstatic<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>10<\/span>]<\/span> args)<\/span> {<\/span>\r\n\t\tString<\/span> s =<\/span> \"abc\"<\/span>\r\n\t\tSystem<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>s)<\/span>;<\/span>\r\n\t}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
            \u30d1\u30c3\u30b1\u30fc\u30b8\u540d\u306b\u306f\u30cf\u30a4\u30d5\u30f3\u3092\u4f7f\u3048\u307e\u305b\u3093\u3002
            \n\u30af\u30e9\u30b9\u540d\u306b\u306f\u30b9\u30da\u30fc\u30b9\u3092\u4f7f\u3048\u307e\u305b\u3093\u3002
            \n\u30e1\u30a4\u30f3\u30e1\u30bd\u30c3\u30c9\u306f\u30d1\u30d6\u30ea\u30c3\u30af\u3067\u306f\u306a\u3044\u306e\u3067\u3001\u5b9f\u884c\u3055\u308c\u307e\u305b\u3093\u3002
            \n\u30e1\u30a4\u30f3\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u3067\u30b5\u30a4\u30ba\u3092\u6307\u5b9a\u3059\u308b\u5fc5\u8981\u306f\u3042\u308a\u307e\u305b\u3093\u3002
            \n\u6587\u5b57\u5217\u306e\u5b9a\u7fa9\u306b\u30bb\u30df\u30b3\u30ed\u30f3\u304c\u629c\u3051\u3066\u3044\u307e\u3059\u3002<\/details>\n
            \u7d50\u8ad6<\/h2>\n
            \u3053\u306e50\u306eJava\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u30a4\u30f3\u30bf\u30d3\u30e5\u30fc\u554f\u984c\u96c6\u306f\u3001\u521d\u5fc3\u8005\u304b\u3089\u4e0a\u7d1a\u8005\u307e\u3067\u306e\u554f\u984c\u3092\u542b\u3093\u3067\u304a\u308a\u3001\u30a4\u30f3\u30bf\u30d3\u30e5\u30fc\u306e\u6e96\u5099\u3092\u30b5\u30dd\u30fc\u30c8\u3057\u307e\u3059\u3002<\/p>\n
            \u304a\u3059\u3059\u3081\u306e\u8aad\u66f8:<\/p>\n
              \n
            • Java Tricky Interview Questions<\/li>\n
            • Java String Interview Questions<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
              \u3042\u3044\u3055\u3064 \u3082\u3057Java\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u5f79\u5272\u306e\u9762\u63a5\u3092\u53d7\u3051\u308b\u306a\u3089\u3070\u3001\u304a\u305d\u3089\u304f\u3042\u306a\u305f\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u30b9\u30ad\u30eb\u304c\u30c6\u30b9\u30c8\u3055\u308c\u307e\u3059\u3002Java\u306e\u521d\u5fc3\u8005\u3067\u3042\u308d\u3046\u3068\u3001\u30a8\u30ad\u30b9\u30d1\u30fc\u30c8\u30d7\u30ed\u30b0\u30e9\u30de\u3067\u3042\u308d\u3046\u3068\u3001\u3053\u306e\u8a18\u4e8b\u306f\u3044\u304f\u3064\u304b\u306e\u4e00\u822c\u7684\u306aJava\u306e\u9762 […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[26,61],"class_list":["post-493","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-26","tag-61"],"yoast_head":"\nJava\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u9762\u63a5\u3067\u3088\u304f\u805e\u304b\u308c\u308b50\u306e\u8cea\u554f\u306e\u30c8\u30c3\u30d7 - 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