{"id":31595,"date":"2022-12-09T14:30:32","date_gmt":"2023-07-01T12:48:09","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/%e5%85%b3%e4%ba%8ejava-optional%e7%9a%84%e4%bd%bf%e7%94%a8%e6%96%b9%e6%b3%95\/"},"modified":"2024-01-15T06:48:45","modified_gmt":"2024-01-14T22:48:45","slug":"%e5%85%b3%e4%ba%8ejava-optional%e7%9a%84%e4%bd%bf%e7%94%a8%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/%e5%85%b3%e4%ba%8ejava-optional%e7%9a%84%e4%bd%bf%e7%94%a8%e6%96%b9%e6%b3%95\/","title":{"rendered":"\u5173\u4e8eJava Optional\u7684\u4f7f\u7528\u65b9\u6cd5"},"content":{"rendered":"

Optional \u7684\u58f0\u660e\u65b9\u5f0f<\/h1>\n

\u4e3a\u4e86\u4f7f\u7528Optional\uff0c\u9700\u8981\u5c06\u7c7b\u578b\u5305\u88c5\u8d77\u6765\u4f7f\u7528\u3002<\/p>\n

Optional<String> opt1;\r\n<\/code><\/pre>\n
\u5373\u4f7f\u5728\u81ea\u5df1\u521b\u5efa\u7684\u7c7b\u4e2d\u4e5f\u662f\u4e00\u6837\u7684<\/p>\n
public<\/span> class<\/span> testClass<\/span>\r\n{<\/span>\r\n    private<\/span> String<\/span> no<\/span>;<\/span>\r\n    private<\/span> BigDecimal<\/span> val<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
OPtional<testClass> opt2;\r\n<\/code><\/pre>\n
\u7528\u6cd5<\/h1>\n
\u8981\u5c06\u503c\u653e\u5165Optional\u7c7b\u578b\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528optional.of\u6216optional.ofNullable\u3002<\/p>\n
Optional<String> opt1 = Optional.of(\"test\");\r\n<\/code><\/pre>\n
\u7136\u800c\uff0c\u53ef\u9009\u7a0b\u5e8foptional.of\u4f1a\u5728\u53c2\u6570\u4e3anull\u7684\u60c5\u51b5\u4e0b\u5f15\u53d1\u5f02\u5e38\uff0c\u56e0\u6b64\u8981\u5c0f\u5fc3\u3002<\/p>\n
Optional<String> opt1 = Optional.of(null);\r\n<\/code><\/pre>\n
\u56e0\u6b64\uff0c\u4f7f\u7528 optional.ofNullable\u3002<\/p>\n
Optional<String> opt1 = Optional.ofNullable(\"test\");\r\nOptional<String> opt2 = Optional.ofNullable(null);\r\n\r\ntestClass test = new testClass();\r\nOptional<String> opt3 = Optional.ofNullable(test);\r\n<\/code><\/pre>\n
\u83b7\u53d6\u503c\u7684\u65b9\u6cd5 (Obtaining the value method)<\/h1>\n
\u4e3a\u4e86\u63d0\u53d6\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u65b9\u6cd5\uff1a
\nget \uff1a\u5982\u679c\u4e3anull\uff0c\u5219\u5f15\u53d1\u5f02\u5e38
\norElse \uff1a\u5982\u679c\u4e0d\u4e3anull\uff0c\u5219\u8fd4\u56de\u53d8\u91cf\u503c\uff0c\u5982\u679c\u4e3anull\uff0c\u5219\u8fd4\u56deorElse\u7684\u53c2\u6570
\norElseGet \uff1a\u5982\u679c\u4e0d\u4e3anull\uff0c\u5219\u8fd4\u56de\u53d8\u91cf\u503c\uff0c\u5982\u679c\u4e3anull\uff0c\u5219\u8fd4\u56desuppelier\u7684\u7ed3\u679c<\/p>\n
String val1 = opt1.get();\r\nString val2 = opt1.orElse(\"\")\r\n<\/code><\/pre>\n
\u5f53\u4ece\u81ea\u5b9a\u4e49\u7c7b\u4e2d\u83b7\u53d6\u503c\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u65b9\u6cd5\u6765\u83b7\u53d6\u5b57\u6bb5\u3002
\n\u5b57\u5178<\/p>\n
String val1 = opt3.map(testClass::getNo).orElse(\"1\");\r\nString val2 = opt3.map(v -> v.getNo()).orElse(\"2\");\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
Optional \u7684\u58f0\u660e\u65b9\u5f0f \u4e3a\u4e86\u4f7f\u7528Optional\uff0c\u9700\u8981\u5c06\u7c7b\u578b\u5305\u88c5\u8d77\u6765\u4f7f\u7528\u3002 Optional<St […]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-31595","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\n\u5173\u4e8eJava Optional\u7684\u4f7f\u7528\u65b9\u6cd5 - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/zh\/blog\/\u5173\u4e8ejava-optional\u7684\u4f7f\u7528\u65b9\u6cd5\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"\u5173\u4e8eJava Optional\u7684\u4f7f\u7528\u65b9\u6cd5\" \/>\n<meta property=\"og:description\" content=\"Optional \u7684\u58f0\u660e\u65b9\u5f0f \u4e3a\u4e86\u4f7f\u7528Optional\uff0c\u9700\u8981\u5c06\u7c7b\u578b\u5305\u88c5\u8d77\u6765\u4f7f\u7528\u3002 Optional<St […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/zh\/blog\/\u5173\u4e8ejava-optional\u7684\u4f7f\u7528\u65b9\u6cd5\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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