{"id":2198,"date":"2025-03-01T18:31:42","date_gmt":"2025-03-01T10:31:42","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=2198"},"modified":"2025-03-01T18:31:42","modified_gmt":"2025-03-01T10:31:42","slug":"java-%e6%9d%a1%e4%bb%b6%e8%af%ad%e5%8f%a5-if-else","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/03\/01\/java-%e6%9d%a1%e4%bb%b6%e8%af%ad%e5%8f%a5-if-else\/","title":{"rendered":"Java \u6761\u4ef6\u8bed\u53e5 – if…else"},"content":{"rendered":"\n

\u5728 Java \u4e2d\uff0c\u6761\u4ef6\u8bed\u53e5\u7528\u4e8e\u6839\u636e\u7279\u5b9a\u7684\u6761\u4ef6\u51b3\u5b9a\u662f\u5426\u6267\u884c\u67d0\u6bb5\u4ee3\u7801\u3002\u6700\u5e38\u89c1\u7684\u6761\u4ef6\u8bed\u53e5\u662f if...else<\/code> \u8bed\u53e5\uff0c\u5b83\u6839\u636e\u6761\u4ef6\u7684\u771f\u5047\u6765\u51b3\u5b9a\u6267\u884c\u7684\u4ee3\u7801\u5757\u3002<\/p>\n\n\n\n

1. if \u8bed\u53e5<\/strong><\/h3>\n\n\n\n

if<\/code> \u8bed\u53e5\u7528\u4e8e\u6839\u636e\u7ed9\u5b9a\u7684\u6761\u4ef6\u5224\u65ad\u662f\u5426\u6267\u884c\u67d0\u6bb5\u4ee3\u7801\u3002\u5176\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n\n\n\n

if (\u6761\u4ef6) {\n    \/\/ \u6761\u4ef6\u4e3a true \u65f6\u6267\u884c\u7684\u4ee3\u7801\n}<\/code><\/pre>\n\n\n\n
    \n
  • \u6761\u4ef6<\/strong>\uff1a\u5fc5\u987b\u662f\u5e03\u5c14\u8868\u8fbe\u5f0f\uff08\u5373\u8fd4\u56de true<\/code> \u6216 false<\/code>\uff09\uff0c\u5982\u679c\u6761\u4ef6\u4e3a true<\/code>\uff0c\u5c31\u4f1a\u6267\u884c if<\/code> \u5757\u4e2d\u7684\u4ee3\u7801\u3002<\/li>\n<\/ul>\n\n\n\n
    \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
    int x = 10;\nif (x > 5) {\n    System.out.println(\"x \u5927\u4e8e 5\");\n}<\/code><\/pre>\n\n\n\n
    \u8f93\u51fa\uff1a<\/p>\n\n\n\n
    x \u5927\u4e8e 5<\/code><\/pre>\n\n\n\n
    2. if\u2026else \u8bed\u53e5<\/strong><\/h3>\n\n\n\n
    if...else<\/code> \u8bed\u53e5\u7528\u4e8e\u5728\u6761\u4ef6\u4e3a true<\/code> \u65f6\u6267\u884c\u4e00\u6bb5\u4ee3\u7801\uff0c\u6761\u4ef6\u4e3a false<\/code> \u65f6\u6267\u884c\u53e6\u4e00\u6bb5\u4ee3\u7801\u3002\u5176\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n\n\n\n
    if (\u6761\u4ef6) {\n    \/\/ \u6761\u4ef6\u4e3a true \u65f6\u6267\u884c\u7684\u4ee3\u7801\n} else {\n    \/\/ \u6761\u4ef6\u4e3a false \u65f6\u6267\u884c\u7684\u4ee3\u7801\n}<\/code><\/pre>\n\n\n\n
      \n
    • \u6761\u4ef6<\/strong>\uff1a\u5982\u679c\u6761\u4ef6\u4e3a true<\/code>\uff0c\u6267\u884c if<\/code> \u90e8\u5206\u7684\u4ee3\u7801\uff1b\u5982\u679c\u6761\u4ef6\u4e3a false<\/code>\uff0c\u5219\u6267\u884c else<\/code> \u90e8\u5206\u7684\u4ee3\u7801\u3002<\/li>\n<\/ul>\n\n\n\n
      \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
      int x = 4;\nif (x > 5) {\n    System.out.println(\"x \u5927\u4e8e 5\");\n} else {\n    System.out.println(\"x \u5c0f\u4e8e\u6216\u7b49\u4e8e 5\");\n}<\/code><\/pre>\n\n\n\n
      \u8f93\u51fa\uff1a<\/p>\n\n\n\n
      x \u5c0f\u4e8e\u6216\u7b49\u4e8e 5<\/code><\/pre>\n\n\n\n
      3. if\u2026else if\u2026else \u8bed\u53e5<\/strong><\/h3>\n\n\n\n
      \u5f53\u6709\u591a\u4e2a\u6761\u4ef6\u9700\u8981\u5224\u65ad\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u591a\u4e2a else if<\/code> \u6765\u589e\u52a0\u6761\u4ef6\u5224\u65ad\u3002\u5982\u679c\u7b2c\u4e00\u4e2a\u6761\u4ef6\u4e0d\u6210\u7acb\uff0c\u7ee7\u7eed\u5224\u65ad\u7b2c\u4e8c\u4e2a\u6761\u4ef6\uff0c\u4f9d\u6b64\u7c7b\u63a8\uff0c\u76f4\u5230\u6240\u6709\u6761\u4ef6\u90fd\u88ab\u68c0\u67e5\u5b8c\u6bd5\u3002\u5176\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n\n\n\n
      if (\u6761\u4ef61) {\n    \/\/ \u6761\u4ef61\u4e3a true \u65f6\u6267\u884c\u7684\u4ee3\u7801\n} else if (\u6761\u4ef62) {\n    \/\/ \u6761\u4ef62\u4e3a true \u65f6\u6267\u884c\u7684\u4ee3\u7801\n} else if (\u6761\u4ef63) {\n    \/\/ \u6761\u4ef63\u4e3a true \u65f6\u6267\u884c\u7684\u4ee3\u7801\n} else {\n    \/\/ \u6240\u6709\u6761\u4ef6\u90fd\u4e0d\u4e3a true \u65f6\u6267\u884c\u7684\u4ee3\u7801\n}<\/code><\/pre>\n\n\n\n
        \n
      • \u6761\u4ef61\u3001\u6761\u4ef62\u3001\u6761\u4ef63\u2026<\/strong>\uff1a\u8fd9\u4e9b\u6761\u4ef6\u662f\u4f9d\u6b21\u68c0\u67e5\u7684\uff0c\u76f4\u5230\u627e\u5230\u7b2c\u4e00\u4e2a true<\/code> \u7684\u6761\u4ef6\u4e3a\u6b62\u3002\u5982\u679c\u90fd\u4e0d\u6210\u7acb\uff0c\u5219\u6267\u884c else<\/code> \u90e8\u5206\u7684\u4ee3\u7801\u3002<\/li>\n<\/ul>\n\n\n\n
        \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
        int x = 7;\nif (x > 10) {\n    System.out.println(\"x \u5927\u4e8e 10\");\n} else if (x > 5) {\n    System.out.println(\"x \u5927\u4e8e 5 \u5c0f\u4e8e\u6216\u7b49\u4e8e 10\");\n} else {\n    System.out.println(\"x \u5c0f\u4e8e\u6216\u7b49\u4e8e 5\");\n}<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\uff1a<\/p>\n\n\n\n
        x \u5927\u4e8e 5 \u5c0f\u4e8e\u6216\u7b49\u4e8e 10<\/code><\/pre>\n\n\n\n
        4. \u5d4c\u5957 if \u8bed\u53e5<\/strong><\/h3>\n\n\n\n
        if<\/code> \u8bed\u53e5\u53ef\u4ee5\u5d4c\u5957\u5728\u53e6\u4e00\u4e2a if<\/code> \u8bed\u53e5\u5185\u90e8\uff0c\u9002\u7528\u4e8e\u591a\u4e2a\u6761\u4ef6\u7684\u590d\u5408\u5224\u65ad\u3002\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n\n\n\n
        if (\u6761\u4ef61) {\n    if (\u6761\u4ef62) {\n        \/\/ \u5f53\u6761\u4ef61 \u548c \u6761\u4ef62 \u90fd\u6210\u7acb\u65f6\u6267\u884c\u7684\u4ee3\u7801\n    }\n}<\/code><\/pre>\n\n\n\n
        \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
        int x = 10, y = 5;\nif (x > 5) {\n    if (y < 10) {\n        System.out.println(\"x \u5927\u4e8e 5 \u4e14 y \u5c0f\u4e8e 10\");\n    }\n}<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\uff1a<\/p>\n\n\n\n
        x \u5927\u4e8e 5 \u4e14 y \u5c0f\u4e8e 10<\/code><\/pre>\n\n\n\n
        5. \u6761\u4ef6\u8fd0\u7b97\u7b26\uff08Ternary Operator\uff09<\/strong><\/h3>\n\n\n\n
        \u9664\u4e86 if...else<\/code> \u8bed\u53e5\u5916\uff0cJava \u8fd8\u63d0\u4f9b\u4e86\u4e00\u79cd\u7b80\u6d01\u7684\u4e09\u5143\u8fd0\u7b97\u7b26\u6765\u5b9e\u73b0\u6761\u4ef6\u5224\u65ad\u3002\u5b83\u7684\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n\n\n\n
        condition ? expression1 : expression2<\/code><\/pre>\n\n\n\n
          \n
        • condition<\/strong>\uff1a\u5e03\u5c14\u6761\u4ef6\u8868\u8fbe\u5f0f\u3002<\/li>\n\n\n\n
        • expression1<\/strong>\uff1a\u5982\u679c\u6761\u4ef6\u4e3a true<\/code>\uff0c\u5219\u8fd4\u56de expression1<\/code> \u7684\u503c\u3002<\/li>\n\n\n\n
        • expression2<\/strong>\uff1a\u5982\u679c\u6761\u4ef6\u4e3a false<\/code>\uff0c\u5219\u8fd4\u56de expression2<\/code> \u7684\u503c\u3002<\/li>\n<\/ul>\n\n\n\n
          \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
          int x = 10;\nString result = (x > 5) ? \"x \u5927\u4e8e 5\" : \"x \u5c0f\u4e8e\u6216\u7b49\u4e8e 5\";\nSystem.out.println(result);<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\uff1a<\/p>\n\n\n\n
          x \u5927\u4e8e 5<\/code><\/pre>\n\n\n\n
          \u603b\u7ed3<\/strong><\/h3>\n\n\n\n
            \n
          • if \u8bed\u53e5<\/strong>\uff1a\u7528\u4e8e\u6839\u636e\u6761\u4ef6\u5224\u65ad\u662f\u5426\u6267\u884c\u67d0\u6bb5\u4ee3\u7801\u3002<\/li>\n\n\n\n
          • if\u2026else \u8bed\u53e5<\/strong>\uff1a\u6839\u636e\u6761\u4ef6\u7684\u771f\u5047\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u5757\u3002<\/li>\n\n\n\n
          • if\u2026else if\u2026else \u8bed\u53e5<\/strong>\uff1a\u7528\u4e8e\u591a\u6761\u4ef6\u5224\u65ad\uff0c\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u5757\u3002<\/li>\n\n\n\n
          • \u5d4c\u5957 if \u8bed\u53e5<\/strong>\uff1a\u5141\u8bb8\u5728 if<\/code> \u8bed\u53e5\u5185\u90e8\u518d\u4f7f\u7528 if<\/code> \u8bed\u53e5\u8fdb\u884c\u66f4\u590d\u6742\u7684\u5224\u65ad\u3002<\/li>\n\n\n\n
          • \u4e09\u5143\u8fd0\u7b97\u7b26<\/strong>\uff1a\u7528\u4e8e\u7b80\u6d01\u5730\u8868\u793a\u6761\u4ef6\u5224\u65ad\uff0c\u9002\u7528\u4e8e\u7b80\u5355\u7684\u6761\u4ef6\u9009\u62e9\u3002<\/li>\n<\/ul>\n\n\n\n
            \u6761\u4ef6\u8bed\u53e5\u662f Java \u7f16\u7a0b\u4e2d\u5e38\u7528\u7684\u63a7\u5236\u7ed3\u6784\u4e4b\u4e00\uff0c\u7528\u4e8e\u6839\u636e\u4e0d\u540c\u7684\u6761\u4ef6\u63a7\u5236\u4ee3\u7801\u7684\u6267\u884c\u6d41\u7a0b\u3002\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
            \u5728 Java \u4e2d\uff0c\u6761\u4ef6\u8bed\u53e5\u7528\u4e8e\u6839\u636e\u7279\u5b9a\u7684\u6761\u4ef6\u51b3\u5b9a\u662f\u5426\u6267\u884c\u67d0\u6bb5\u4ee3\u7801\u3002\u6700\u5e38\u89c1\u7684\u6761\u4ef6\u8bed\u53e5\u662f if…else \u8bed\u53e5 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[68],"tags":[],"class_list":["post-2198","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2198","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=2198"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2198\/revisions"}],"predecessor-version":[{"id":2199,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2198\/revisions\/2199"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=2198"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=2198"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=2198"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}