{"id":50677,"date":"2023-01-31T20:25:10","date_gmt":"2023-08-22T14:12:18","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/%e5%a6%82%e4%bd%95%e5%9c%a8java%e4%b8%ad%e5%b0%86set%e8%bd%ac%e6%8d%a2%e4%b8%balist\/"},"modified":"2024-04-29T12:26:46","modified_gmt":"2024-04-29T04:26:46","slug":"%e5%a6%82%e4%bd%95%e5%9c%a8java%e4%b8%ad%e5%b0%86set%e8%bd%ac%e6%8d%a2%e4%b8%balist","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/%e5%a6%82%e4%bd%95%e5%9c%a8java%e4%b8%ad%e5%b0%86set%e8%bd%ac%e6%8d%a2%e4%b8%balist\/","title":{"rendered":"\u5982\u4f55\u5728Java\u4e2d\u5c06Set\u8f6c\u6362\u4e3aList"},"content":{"rendered":"

\u5728Java\u4e2d\uff0c\u5217\u8868\u662f\u6709\u5e8f\u7684\u6570\u636e\u96c6\u5408\uff0c\u800c\u96c6\u5408\u662f\u65e0\u5e8f\u7684\u6570\u636e\u96c6\u5408\u3002\u5217\u8868\u53ef\u4ee5\u6709\u91cd\u590d\u7684\u6761\u76ee\uff0c\u800c\u96c6\u5408\u5219\u4e0d\u80fd\u3002\u8fd9\u4e24\u79cd\u6570\u636e\u7ed3\u6784\u5728\u4e0d\u540c\u7684\u573a\u666f\u4e2d\u90fd\u5f88\u6709\u7528\u3002<\/p>\n

\u77e5\u9053\u5982\u4f55\u5c06\u96c6\u5408\u8f6c\u6362\u4e3a\u5217\u8868\u5f88\u6709\u7528\u3002\u5b83\u53ef\u4ee5\u5c06\u65e0\u5e8f\u7684\u6570\u636e\u8f6c\u6362\u4e3a\u6709\u5e8f\u7684\u6570\u636e\u3002<\/p>\n

\u521d\u59cb\u5316\u4e00\u4e2a\u96c6\u5408<\/h2>\n

\u8ba9\u6211\u4eec\u521d\u59cb\u5316\u4e00\u4e2a\u96c6\u5408\u5e76\u5411\u5176\u4e2d\u6dfb\u52a0\u4e00\u4e9b\u5143\u7d20\u3002<\/p>\n

import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>a)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"Set\"<\/div>\n
HashSet\u7684add()\u65b9\u6cd5\u5c06\u5143\u7d20\u6dfb\u52a0\u5230\u96c6\u5408\u4e2d\u3002\u8bf7\u6ce8\u610f\uff0c\u8fd9\u4e9b\u5143\u7d20\u662f\u4e0d\u91cd\u590d\u7684\u3002\u7531\u4e8e\u96c6\u5408\u662f\u65e0\u5e8f\u7684\uff0c\u6240\u4ee5\u65e0\u6cd5\u6309\u7167\u63d2\u5165\u987a\u5e8f\u83b7\u53d6\u5143\u7d20\u3002<\/p>\n
\u5728Java\u4e2d\u5c06Set\u8f6c\u6362\u4e3aList<\/h2>\n
\u8ba9\u6211\u4eec\u5c06\u96c6\u5408\u8f6c\u6362\u4e3a\u5217\u8868\u3002\u6709\u591a\u79cd\u65b9\u6cd5\u53ef\u4ee5\u505a\u5230\u8fd9\u4e00\u70b9\u3002\u6bcf\u79cd\u65b9\u6cd5\u90fd\u4e0e\u5176\u4ed6\u65b9\u6cd5\u4e0d\u540c\uff0c\u800c\u4e14\u8fd9\u4e9b\u5dee\u5f02\u662f\u5fae\u5999\u7684\u3002<\/p>\n
\u7528\u96c6\u5408\u53c2\u6570\u7684\u5217\u8868\u6784\u9020\u51fd\u6570<\/h3>\n
\u5c06\u96c6\u5408\u8f6c\u6362\u4e3a\u5217\u8868\u7684\u6700\u76f4\u63a5\u7684\u65b9\u6cd5\u662f\u5728\u521b\u5efa\u5217\u8868\u65f6\u5c06\u96c6\u5408\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u3002\u8fd9\u6837\u8c03\u7528\u6784\u9020\u51fd\u6570\uff0c\u4ece\u90a3\u91cc\u5f00\u59cb\u6784\u9020\u51fd\u6570\u5c31\u4f1a\u81ea\u884c\u5904\u7406\u5269\u4e0b\u7684\u90e8\u5206\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>a)<\/span>;<\/span>\r\n     System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n     System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"Using<\/div>\n
\u7531\u4e8e\u96c6\u5408\u5df2\u7ecf\u8f6c\u6362\u4e3a\u5217\u8868\uff0c\u5143\u7d20\u73b0\u5728\u662f\u6709\u5e8f\u7684\u3002\u8fd9\u610f\u5473\u7740\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 get() \u65b9\u6cd5\u901a\u8fc7\u7d22\u5f15\u8bbf\u95ee\u5143\u7d20\u3002<\/p>\n
\u4f7f\u7528\u4f20\u7edf\u7684for\u5faa\u73af\u65b9\u5f0f<\/h3>\n
\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u7ecf\u5178\u7684for\u5faa\u73af\u6765\u5c06\u96c6\u5408\u4e2d\u7684\u5143\u7d20\u660e\u786e\u5730\u590d\u5236\u5230\u5217\u8868\u4e2d\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>a)<\/span>;<\/span>\r\n        for<\/span> (<\/span>int<\/span> i :<\/span> a)<\/span>\r\n            arr.<\/span>add<\/span>(<\/span>i)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>   \r\n}<\/span>\r\n<\/code><\/pre>\n
\"Using<\/div>\n
For\u5faa\u73af\u6309\u7167\u96c6\u5408\u4e2d\u7684\u5143\u7d20\u9010\u4e2a\u8fdb\u884c\u904d\u5386\uff0c\u5e76\u5c06\u5143\u7d20\u6dfb\u52a0\u5230\u5217\u8868\u4e2d\u3002<\/p>\n
3. \u5217\u8868\u7684addAll()\u65b9\u6cd5<\/h3>\n
\u5217\u8868\u5177\u6709\u4e00\u4e2a\u79f0\u4e3aaddAll\uff08\uff09\u7684\u65b9\u6cd5\uff0c\u5b83\u53ef\u4ee5\u4e00\u6b21\u5411\u5217\u8868\u4e2d\u6dfb\u52a0\u591a\u4e2a\u503c\u3002\u60a8\u53ef\u80fd\u4f1a\u5728\u5408\u5e76\u4e24\u4e2a\u5217\u8868\u65f6\u4f7f\u7528\u6b64\u64cd\u4f5c\u3002addAll\uff08\uff09\u8fd8\u53ef\u7528\u4e8e\u5c06\u96c6\u5408\u7684\u5143\u7d20\u6dfb\u52a0\u5230\u5217\u8868\u4e2d\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        arr.<\/span>addAll<\/span>(<\/span>a)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"Using<\/div>\n
4. Stream API collect\uff08\uff09\u65b9\u6cd5<\/h3>\n
Stream API\u7684collect\uff08\uff09\u65b9\u6cd5<\/p>\n
\u4eceJava 8\u5f00\u59cb\uff0c\u53ef\u4ee5\u4f7f\u7528Stream.collect()\u65b9\u6cd5\u3002ToList\u6536\u96c6\u5668\u5c06\u6240\u6709Stream\u5143\u7d20\u6536\u96c6\u5230\u4e00\u4e2aList\u5b9e\u4f8b\u4e2d\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>stream.<\/span><\/span>Collectors<\/span><\/span>;<\/span>\r\n\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr;<\/span>\r\n\r\n        arr =<\/span> a.<\/span>stream<\/span>(<\/span>)<\/span>.<\/span>collect<\/span>(<\/span>Collectors<\/span>.<\/span>toList<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"using<\/div>\n
stream.collect()\u7684\u6587\u6863\u63d0\u5230\u4e86\u8fd4\u56de\u7684List\u7684\u7c7b\u578b\u3001\u53ef\u53d8\u6027\u3001\u5e8f\u5217\u5316\u6027\u6216\u7ebf\u7a0b\u5b89\u5168\u6027\u6ca1\u6709\u4fdd\u8bc1\u3002\u5982\u679c\u9700\u8981\u5bf9\u8fd4\u56de\u7684List\u6709\u66f4\u591a\u7684\u63a7\u5236\uff0c\u53ef\u4ee5\u4f7f\u7528toCollection(Supplier)\u65b9\u6cd5\u3002<\/p>\n
\u4f7f\u7528 toCollection(ArrayList::new) \u6765\u6307\u5b9a\u5217\u8868\u7684\u7c7b\u578b\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>stream.<\/span><\/span>Collectors<\/span><\/span>;<\/span>\r\n\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr;<\/span>\r\n\r\n  arr =<\/span> a.<\/span>stream<\/span>(<\/span>)<\/span>.<\/span>collect<\/span>(<\/span>Collectors<\/span>.<\/span>toCollection<\/span>(<\/span>ArrayList<\/span>::<\/span>new<\/span>)<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u63a8\u8350\u9605\u8bfb\uff1aJava\u4e2d\u7684\u6d41<\/p>\n
5. List.copyOf() \u65b9\u6cd5<\/h3>\n
\u4eceJava 10\u5f00\u59cb\uff0cList\u7c7b\u62e5\u6709\u4e00\u4e2acopyOf()\u65b9\u6cd5\u3002\u8be5\u65b9\u6cd5\u8fd4\u56de\u4e00\u4e2a\u4e0d\u53ef\u4fee\u6539\u7684\u5217\u8868\uff0c\u5176\u4e2d\u5305\u542b\u7ed9\u5b9a\u96c6\u5408\u7684\u5143\u7d20\uff0c\u5e76\u6309\u7167\u8fed\u4ee3\u987a\u5e8f\u6392\u5217\u3002\u5217\u8868\u4e2d\u4e0d\u5141\u8bb8\u5305\u542b\u4efb\u4f55\u7a7a\u5143\u7d20\u3002\u5982\u679c\u96c6\u5408\u4e2d\u5305\u542b\u6709”null”\uff0c\u8be5\u65b9\u6cd5\u5c06\u8fd4\u56de\u4e00\u4e2a\u7a7a\u6307\u9488\u5f02\u5e38\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>stream.<\/span><\/span>Collectors<\/span><\/span>;<\/span>\r\n\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr;<\/span>\r\n\r\n        arr =<\/span> List<\/span>.<\/span>copyOf<\/span>(<\/span>a)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"using<\/div>\n
\u5728\u96c6\u5408\u4e2d\u6dfb\u52a0\u4e00\u4e2a\u7a7a\u503c\uff0c\u5e76\u5c1d\u8bd5\u5c06\u5176\u8f6c\u6362\u4e3a\u5217\u8868\u3002<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>stream.<\/span><\/span>Collectors<\/span><\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>null<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr;<\/span>\r\n\r\n        arr =<\/span> List<\/span>.<\/span>copyOf<\/span>(<\/span>a)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"Null<\/div>\n
\u5f53\u60a8\u5c1d\u8bd5\u5c06\u5143\u7d20\u6dfb\u52a0\u5230\u4e0d\u53ef\u53d8\u5217\u8868\u65f6\uff0c\u60a8\u5c06\u6536\u5230\u4ee5\u4e0b\u7c7b\u4f3c\u7684\u9519\u8bef\u63d0\u793a\u3002<\/p>\n
\"Immutable<\/div>\n
\u4f7f\u7528addAll\uff08\uff09\u65b9\u6cd5\u5c06\u5305\u542b\u7a7a\u5143\u7d20\u7684\u96c6\u5408\u8f6c\u6362\u4e3a\u5217\u8868\uff1a<\/p>\n
import<\/span> java.<\/span>util.<\/span><\/span>*<\/span><\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>stream.<\/span><\/span>Collectors<\/span><\/span>;<\/span>\r\n\r\n\r\npublic<\/span> class<\/span> Main<\/span> {<\/span>\r\n\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span>\r\n    {<\/span>\r\n        Set<\/span><<\/span>Integer<\/span>><\/span><\/span> a =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>2<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>3<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>1<\/span>)<\/span>;<\/span>\r\n        a.<\/span>add<\/span>(<\/span>null<\/span>)<\/span>;<\/span>\r\n\r\n     List<\/span><<\/span>Integer<\/span>><\/span><\/span> arr =<\/span> new<\/span> ArrayList<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n     arr.<\/span>addAll<\/span>(<\/span>a)<\/span>;<\/span>\r\n\r\n      \/\/  arr = List.copyOf(a);<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>arr.<\/span>get<\/span>(<\/span>1<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\"AddAll()<\/div>\n
\u8bf7\u6ce8\u610f\uff0c\u7a7a\u503c\u51fa\u73b0\u5728\u5217\u8868\u7684\u5f00\u5934\u3002<\/p>\n
\u7ed3\u8bba\u662f<\/h2>\n
\u6211\u4eec\u770b\u5230\u4e86\u4e00\u4e9b\u975e\u5e38\u6709\u8da3\u7684\u65b9\u6cd5\u5c06\u4e00\u4e2a\u96c6\u5408\u8f6c\u6362\u4e3a\u5217\u8868\u3002\u5173\u6ce8\u4ece\u6bcf\u4e2a\u65b9\u6cd5\u521b\u5efa\u7684\u5217\u8868\u7c7b\u578b\u975e\u5e38\u91cd\u8981\u3002\u4f8b\u5982\uff0ccopyOf()\u65b9\u6cd5\u4ea7\u751f\u4e00\u4e2a\u4e0d\u53ef\u53d8\u7684\u5217\u8868\uff0c\u4e0d\u80fd\u5904\u7406\u7a7a\u5143\u7d20\u3002\u800cstream.collect()\u65b9\u6cd5\u6ca1\u6709\u4efb\u4f55\u4fdd\u8bc1\u3002\u6784\u9020\u51fd\u6570\u548caddAll()\u65b9\u6cd5\u662f\u6279\u5904\u7406\u4e2d\u6700\u53ef\u4fe1\u8d56\u7684\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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