{"id":104135,"date":"2020-02-24T03:21:20","date_gmt":"2020-02-23T19:21:20","guid":{"rendered":"http:\/\/4563.org\/?p=104135"},"modified":"2020-02-24T03:21:20","modified_gmt":"2020-02-23T19:21:20","slug":"java-%e5%a6%82%e4%bd%95%e5%a4%84%e7%90%86%e7%a9%ba%e6%8c%87%e9%92%88%ef%bc%9f","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=104135","title":{"rendered":"Java :\u5982\u4f55\u5904\u7406\u7a7a\u6307\u9488\uff1f"},"content":{"rendered":"
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Java :\u5982\u4f55\u5904\u7406\u7a7a\u6307\u9488\uff1f <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : sandman511 <\/span> <\/i> 51<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n
Integer code = getCode(); String codeMeaning = code == null ? null :                     code == 1 ? \"\u4f60\u597d\" :                     code == 2 ? \"\u4f60\u597d\u597d\" :                     code == 3 ? \"\u4f60\u597d\u597d\u597d\"; <\/code><\/pre>\n
\u8bf7\u5404\u5927\u4f6c\u5e2e\u5fd9\u4fee\u6539\u8fd9\u6bb5\u4ee3\u7801
 code == null ? null \u770b\u8d77\u6765\u6709\u70b9\u602a\u602a\u7684<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (57<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : avk458 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e09\u5143\u8868\u8fbe\u5f0f\u8fd8\u80fd\u8fd9\u6837\u73a9\u513f\uff1f
    \u6309\u7167\u8fd9\u4e2a`codeMeaning`\u7684\u610f\u601d\u6765\u7528 switch \u662f\u4e0d\u662f\u66f4\u597d\uff1f
    \u5305\u88c5\u7c7b\u6bd4\u8f83\u662f\u4e0d\u662f\u5e94\u8be5\u7528 equals \uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : pmispig <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8c01\u5199\u7684\uff0c\u5148\u628a\u4ed6\u5934\u9524\u7206                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : Lin0936 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \/\/ TODO: Bullshit                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : sandman511 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @pmispig \u5b9e\u4e0d\u76f8\u7792\u3002\u3002\u6211\u5199\u7684\u3002\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : manami <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 Objects.equals(a, b)                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : optional <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \/\/ \u7b2c\u4e00\u79cd\u63d0\u524d\u8fd4\u56de
    “`
    if (Objects.isNull(code)) {
     return null;
    }
    \/\/switch or if
    “`
    \/\/\u7b2c\u4e8c\u79cd\uff0c
    “`
    Optional.ofNullable(code).map(code->{
    \/\/switch or if
    }).orElse(null);
    “`                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : passerbytiny <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e00\uff0cJava \u6ca1\u6709\u6307\u9488\uff1b
    \u4e8c\uff0c\u4e09\u5143\u8fde\u63a5\u7b26\u5d4c\u5957\u4f7f\u7528\u662f\u5927\u5fcc\uff1b
    \u4e09\uff0cif(some == null) { \/\/bulabula when null }else{ \/\/bulabula when not null}\uff0c\u6216\u8005 if(some != null){bulabula}\uff0c\u6216\u8005 some.ifPresent((value)->{\/bulabula})\uff0c \u662f\u826f\u597d\u7684\u7f16\u7801\u4e60\u60ef\uff1b
    \u56db\uff0c\u8bf7\u5584\u7528\u9ed8\u8ba4\u503c\uff1a
     Integer code = getCode();
     String codeMeaning == null ;\/\/ \u6216\u8005 “\u9ed8\u8ba4\u503c”
     if(code != null){
     switch (code.intValue()){
     case 1 : codeMeaning = “\u4f60\u597d”; break;
     \/\/ ……
     } 
     }                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : sandman511 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @avk458 \u6211\u5acc switch \u5199\u8d77\u6765\u592a\u9ebb\u70e6\u4e86 \u8fd9\u4e2a\u903b\u8f91\u6bd4\u8f83\u7b80\u5355 \u5c31\u4e09\u884c \u6240\u4ee5\u7528\u4e86\u4e09\u5143\u3002\u3002\u3002\u8bf7\u6559\u4e00\u4e0b\u4e09\u5143\u4e0d\u80fd\u8fd9\u6837\u7528\u5417\uff1f
    \u786e\u5b9e\u8be5\u7528 equals\uff0c\u4f46\u662f code \u53ef\u80fd\u4e3a null\uff0cequals \u53ef\u80fd\u629b\u7a7a\u6307\u9488\u3002\u3002\u6240\u4ee5\u4e0d\u77e5\u9053\u8be5\u548b\u529e\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : lff0305 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 “`
     Optional<Integer> code = Optional.ofNullable(getCode());
     String s = code.map(c -> {
     switch (c) {
     case 1: return “one”;
     case 2: return “two”;
     }
     return “other”;
     }).orElse(null);
    “`                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : ily433664 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 Map<Integer, String> map = new ….
    codeMeaning = map.get(code);                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : littleylv <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5b9e\u4e0d\u76f8\u7792\uff0c\u4e09\u5143\u8fd9\u4e48\u5d4c\u5957\u4e0d\u52a0\u62ec\u53f7\u7684\uff0c\u9664\u4e86\u50bb\u903c\u7b14\u8bd5\u9898\u5916\uff0c\u5de5\u4f5c\u4e2d\u8fd9\u6837\u5199\u7684\u540c\u4e8b\u6211\u4f1a\u6253\u6b7b\u4ed6\uff08\u4e0d\u662f\u4e0d\u80fd\u5d4c\u5957\uff0c\u4f60\u5f97\u52a0\u62ec\u53f7\u589e\u52a0\u53ef\u8bfb\u6027\uff09                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : lihongjie0209 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e0d\u52a0\u62ec\u53f7\u5c31\u662f\u4f5c\u6b7b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : w292614191 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6211\u611f\u89c9\u6bd4\u4e0a\u90a3\u4e9b if else switch \u597d\u770b\u591a\u4e86\u3002<\/p>\n
    \u90fd\u662f\u4e9b\u79c0\u65e0\u610f\u4e49\u4ee3\u7801\u7684\u3002<\/p>\n
    \u4f60\u770b\u770b 7\u30019 \uff0c<\/p>\n
    \u786c\u662f\u52a0\u957f\u4ee3\u7801\uff0c\u6beb\u65e0\u610f\u4e49\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : Jimmy2Angel <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @passerbytiny \u4e00\uff0c\u4f60\u771f\u662f\u4e2a\u5408\u683c\u7684\u6760\u7cbe                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : ipwx <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 private static final String[] lookup = {null, “\u4f60\u597d”, “\u4f60\u597d\u597d”, “\u4f60\u597d\u597d\u597d”};
    String codeMeaning = lookup[code != null? code.intValue() : 0];<\/p>\n
    https:\/\/ideone.com\/7rXSyK                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : matepi <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 enum \u7279\u6027\u90fd\u591a\u5c11\u5e74\u4e86\u5427                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : banmuyutian <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @w292614191 
    \u201c\u786c\u662f\u52a0\u957f\u4ee3\u7801\uff0c\u6beb\u65e0\u610f\u4e49\u3002\u201d\uff1f
    \u7b49\u4f60\u770b\u5230\u90a3\u4e9b\u96be\u4ee5\u9605\u8bfb\u7ef4\u62a4\u7684\u4ee3\u7801\u5c31\u77e5\u9053\u4ee3\u7801\u89c4\u8303\u7684\u91cd\u8981\u6027\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : micean <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u633a\u6e05\u6670\u7684\uff0c\u52a0\u5565\u62ec\u53f7\uff1f\u6709\u6362\u884c\u548c\u7f29\u8fdb\u8fd8\u4e0d\u591f\u5417\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : lhx2008 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 enum \u5427\uff0c\u6216\u8005 map
    code \u7684\u8bdd\uff0cnull \u5c31\u6574\u4e2a-1 \u5457\uff0cnull \u6765 null \u53bb\u7684                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : wysnylc <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 optional+switch,\u6216\u8005\u7528 java 13 \u8fd8\u662f 14 \u7684\u65b0 switch                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : kkkkkrua <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 switch \u4e0d\u5c31\u597d\u4e86\u4e48\uff0c\u7528 default \u5904\u7406 null                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : sagaxu <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5e94\u8be5\u7528 int\uff0c\u907f\u514d Integer\uff0ccode \u589e\u52a0\u4e00\u9879\u8868\u793a\u539f\u6765\u7528 null \u8868\u793a\u7684\u60c5\u51b5\u3002\u5176\u5b9e\u7528 enum \u4e0d\u662f\u66f4\u597d\u5417\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : Sqpan2 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u505a\u4e2a\u679a\u4e3e\u4e0d\u9999\u5417\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : sandman511 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Sqpan2 
    @sagaxu 
    @lhx2008 
    @matepi 
    \u4e0d\u80fd\u7528\u679a\u4e3e\u54c8\uff0c\u56e0\u4e3a code=1 \u4e0d\u4e00\u5b9a\u4ee3\u8868\u5c31\u662f\u201d\u4f60\u597d\u201c \u53ea\u662f\u5728\u8fd9\u4e2a\u5730\u65b9\u7b49\u4e8e\u201d\u4f60\u597d”
    \u5728\u53e6\u4e00\u4e2a\u65b9\u6cd5\u91cc\u53ef\u80fd\u5c31\u662f\u201d\u4f60\u597d\u597d\u597d\u201c
    \u9664\u975e\u521b\u5efa 7\u30018 \u4e2a\u679a\u4e3e\u7c7b\uff0c\u6bcf\u4e2a\u679a\u4e3e\u7c7b\u4e2d\u5c31\u4e09\u4e2a\u53c2\u6570\u3002\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : oneisall8955 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 var table=new HashMap<Integer,String>(){
     {
     put(k1,v1);
     put(k2,v2);
     \/\/ …
     }
    };<\/p>\n
    table.get(xx)                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : zzzHas <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5982\u679c\u80fd\u63d0\u9ad8\u9605\u8bfb\u6027, \u4ee3\u7801\u957f\u70b9\u5c31\u957f\u70b9.                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : looseChen <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u522b\u7279\u4e48\u7684\u73a9\u4e9b\u82b1\u91cc\u80e1\u54e8\u7684\u73a9\u610f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : wesnow <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4ee3\u7801\u66f4\u5bb9\u6613\u9605\u8bfb\u6bd4\u4ee3\u7801\u7684\u957f\u77ed\u91cd\u8981\u5f97\u591a\uff0c\u751a\u81f3\u53ef\u4ee5\u8bf4\u9664\u975e\u662f\u975e\u5e38\u6781\u7aef\u7684\u60c5\u51b5\uff08\u6bd4\u5982\u6709\u4e2a\u5730\u65b9\u786e\u5b9e\u5bf9\u6027\u80fd\u8981\u6c42\u5f88\u9ad8\uff0c\u8fd9\u91cc\u5c31\u53ef\u80fd\u727a\u7272\u90e8\u5206\u9605\u8bfb\u6027\uff09\uff0c\u5426\u5219\u90fd\u5e94\u8be5\u628a\u4ee3\u7801\u66f4\u5bb9\u6613\u9605\u8bfb\u66f4\u5bb9\u6613\u7406\u89e3\u653e\u5728\u7b2c\u4e00\u4f4d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : qyvlik <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @ipwx #15 \u8fd9\u79cd\u67e5\u8868\u6cd5\u53ef\u8fd8\u884c\u3002\u7701\u53bb if, switch \u7684\u903b\u8f91\u5224\u65ad\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : wc951 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 java8 \u7684 optional \u662f\u6700\u4f18\u96c5\u7684                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : 1et <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 int a = 1,b=2,c=3;
    int d = a+++b+++c;                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : palmers <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6309\u7167\u4f60\u56de\u590d\u7684#24 \u6211\u89c9\u5f97\u53ef\u4ee5\u4f7f\u7528\u679a\u4e3e\u533a\u5206\u8c03\u7528\u7c7b\u522b\uff0c \u7136\u540e\u8fd4\u56de\u5b57\u7b26\u4e32\u62bd\u8c61\u4e3a\u65b9\u6cd5 \u5e94\u8be5\u53ef\u4ee5\u8fbe\u5230\u4f60\u7684\u76ee\u7684\uff0c \u8fd9\u4e48\u7528\u786e\u5b9e\u4e0d\u592a\u597d \u9664\u4e86\u79c0\u4e5f\u6ca1\u6709\u8fbe\u5230\u7b80\u6d01\u7684\u76ee\u7684\uff0c \u7ef4\u62a4\u4f1a\u8d8a\u6765\u8d8a\u4e71 \u4e34\u65f6\u7528\u4e00\u4e0b\u5c31\u6ca1\u4ec0\u4e48\u4e86
    \u4e0d\u77e5\u9053\u4f60\u771f\u662f\u7684\u9700\u6c42\u662f\u4ec0\u4e48 \u5c31\u76ee\u524d\u4f60\u66b4\u9732\u7684\u610f\u613f \u6211\u89c9\u5f97 \u679a\u4e3e+\u62bd\u8c61\u53ef\u4ee5\u5f88\u597d\u7684\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898 \u4e5f\u7b26\u5408\u5f00\u95ed\u539f\u5219                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : ymz <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @kkkkkrua null \u7684\u8bdd\u62a5\u7a7a\u6307\u9488\u9519\u8bef\uff0c\u5230\u4e0d\u4e86 default                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : guyeu <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 String result = switch (Objects.requireNonNullElse(code, 0)) {
     case 0 -> null;
     case 1 -> “\u4f60\u597d”;
     case 2 -> “\u4f60\u597d\u597d”;
     case 3 -> “\u4f60\u597d\u597d\u597d”;
     default -> throw new UnsupportedOperationException();
     };                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : kkkkkrua <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @ymz #33 \u5b66\u5230\u4e86\uff0c\u8c22\u8c22                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : hhhsuan <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4ee3\u7801\u7684\u9996\u8981\u4f5c\u7528\u662f\u7ed9\u4eba\u770b\uff0c\u53ea\u662f\u968f\u4fbf\u53ef\u4ee5\u8fd0\u884c\u4e00\u4e0b\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : oaix <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 Optional \u4e00\u822c\u53ea\u5efa\u8bae\u7528\u5728\u65b9\u6cd5\u7684\u8fd4\u56de\u503c\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : ilumer <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 optional+enum \u6216\u8005 optional+map \u5728 map \u91cc\u9762\u5199 if else \u7684\u903b\u8f91                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : sandman511 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @palmers \u6211\u53c8\u5728\u4e3b\u8d34 APPEND \u4e86\u4e00\u4e0b\u771f\u6b63\u7684\u9700\u6c42                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : earther01 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @oaix \u4e3a\u5565\u5462\uff0c\u662f\u6548\u7387\u4e0d\u9ad8\u5417\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : oaix <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @earther01 \u4e0d\u76f4\u89c2\u3002
    https:\/\/dzone.com\/articles\/using-optional-correctly-is-not-optional \u7b2c 12 \u6761                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : wutiantong <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4ece append \u7684\u4ee3\u7801\u6765\u770b\uff0c\u4f60\u5e94\u8be5\u628a Integer unit + String transferredUnit \u8fd9\u4e24\u6837\u4e1c\u897f wrap \u6210\u4e00\u4e2a\u7b80\u5355\u7684 class\uff0c\u4e0d\u59a8\u5c31\u8fd8\u53eb unit \u597d\u4e86\uff0c\u6570\u5b57\u548c\u5b57\u7b26\u4e32\u4f5c\u4e3a unit \u8fd9\u4e2a class \u7684\u4e24\u4e2a\u6210\u5458\u5c5e\u6027\u3002<\/p>\n
    \u4f60\u7684 getUnit(type) \u5e94\u8be5\u76f4\u63a5\u8fd4\u56de\u8fd9\u4e2a unit class\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : palmers <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 public enum UnitOfWeight {
     KG(“kg”) {
     @Override
     public boolean match(int unit) {
     return false;
     }
     },
     GRAM(“g”) {
     @Override
     public boolean match(int unit) {
     return false;
     }
     },
     TON(“t”) {
     @Override
     public boolean match(int unit) {
     return false;
     }
     },
     UNKNOWN(“x-0”){
     @Override
     public boolean match(int unit) {
     return false;
     }<\/p>\n
     @Override
     public boolean unknown() {
     return true;
     }
     };<\/p>\n
     \/**
     * e.g. kg, g, t
     *\/
     @Getter
     private String note;<\/p>\n
     static UnitOfWeight[] units = UnitOfWeight.values();<\/p>\n
     \/**
     * kg’s enums
     *\/
     static int[] kgs = {1, -1, 4};
     \/**
     * gram’s enums
     *\/
     static int[] grams = {2, 0, 5};
     \/**
     * ton’s enums
     *\/
     static int[] tons = {3, 1, 6};<\/p>\n
     UnitOfWeight(String note) {
     this.note = note;
     }<\/p>\n
     public static UnitOfWeight valueOf(Integer unit) {
     for (UnitOfWeight ofWeight : units) {
     if (unit == null) {
     return UNKNOWN;
     }
     if (ofWeight.match(unit)) {
     return ofWeight;
     }
     }
     return UNKNOWN;
     }<\/p>\n
     \/**
     * \u83b7\u53d6\u5bf9\u5e94\u679a\u4e3e
     * @param unit
     * @return
     *\/
     public abstract boolean match(int unit);<\/p>\n
     \/**
     * \u9519\u8bef\u7684\u503c
     * @return
     *\/
     public boolean unknown() {
     return false;
     }<\/p>\n
     public static void main(String[] args) {
     Integer unit = null;
     \/\/getUnit (type2);
     UnitOfWeight ofWeight = UnitOfWeight.valueOf(unit);
     if (!ofWeight.unknown()) {
     String transferredUnit = ofWeight.getNote();
     \/\/…
     }
     }
    }<\/p>\n
    \u6839\u636e\u4f60 append \u7684\u4ee3\u7801\u7528\u4e86\u4e00\u4e2a\u679a\u4e3e\u6765\u505a\uff0c \u6839\u636e\u4f60\u7684\u63cf\u8ff0\u6211\u60f3\u6709\u51e0\u4e2a\u70b9\u9700\u8981\u6269\u5c55\uff0c
    1. \u4ece pdf \u89e3\u6790 type \u503c\uff1b 
    2. \u6709\u5f88\u591a\u60c5\u51b5\uff08\u53ef\u80fd\u56e0\u4e3a\u5386\u53f2\u539f\u56e0\u5f88\u591a\u5730\u65b9\u4f7f\u7528\u4e86\u4e0d\u540c\u7684\u503c\u4ee3\u8868\u67d0\u4e00\u4e2a\u5355\u4f4d\uff09\uff1b 
    \u6240\u4ee5\u6211\u5efa\u8bae\u4f7f\u7528\u679a\u4e3e\uff0c \u539f\u56e0\u662f:
    1. \u6211\u89c9\u5f97\u540e\u9762\u968f\u7740\u4e1a\u52a1\u9700\u8981\u6216\u8005\u5176\u4ed6\u539f\u56e0\u91cd\u6784\uff0c \u53ef\u80fd\u6162\u6162\u7684\u8fd9\u4e9b\u4ee3\u8868\u67d0\u4e00\u4e2a\u5355\u4f4d\u7684\u503c\u4f1a\u6539\u53d8\u6216\u8005\u7edf\u4e00\u4e3a\u4e00\u4e2a\uff0c\u6240\u4ee5\u4f60\u9700\u8981\u4fee\u6539 \u901a\u8fc7\u679a\u4e3e\u53ef\u4ee5\u7edf\u4e00\u5728\u4e00\u5904\uff0c\u4fbf\u4e8e\u4fee\u6539\uff1b
    2. \u518d\u8005\u4e5f\u65b9\u4fbf\u8fd4\u56de\u7684\u5b57\u7b26\u503c\u53d8\u66f4 \u603b\u4e4b\u5bf9\u4e8e\u53d8\u66f4\u8fd9\u4e2a\u679a\u4e3e\u7c7b\u57fa\u672c\u4e0a\u53ef\u4ee5\u5e94\u5bf9 90%\u4ee5\u4e0a\u7684\u60c5\u51b5;
    3. match \u65b9\u6cd5\u53ef\u4ee5\u505a\u9488\u5bf9\u884c\u7684\u6269\u5c55\u548c\u4f18\u5316\uff1b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : boileryao <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 “`java
    \/\/ Put this map somewhere
    Map<Integer, String> codeMeaningInfo = new HashMap<>();
    codeMeaningInfo.put(1, “\u4f60\u597d”);
    codeMeaningInfo.put(2, “\u4f60\u597d\u597d”);
    codeMeaningInfo.put(3, “\u4f60\u597d\u597d\u597d”);<\/p>\n
    \/\/ Using this map
    String codeMeaning = codeMeaningInfo.get(code);
    “`
    \u4e00\u822c\u60c5\u51b5\u4e0b Map \u5e94\u8be5\u5168\u5c40\u552f\u4e00\uff0c\u53e6\u5916\u63a8\u8350 Kotlin \u7684 `when` \u8868\u8fbe\u5f0f\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : loryyang <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u53ef\u4ee5\u7684\u8bdd\uff0c\u5c3d\u91cf\u4e0d\u8981\u7528 null\uff0c\u5bb9\u6613\u5728\u5404\u79cd\u4f20\u9012\u8fd0\u7b97\u4e2d\u51fa\u73b0\u7a7a\u6307\u9488\u5f02\u5e38\u3002\u6bd4\u5982\u4f60\u8fd9\u4e2a code \u548c codeMeaning\uff0ccode=-1\uff0ccodeMeaning=\u201c\u201d\u8868\u793a\u5f02\u5e38\u3002\u751a\u81f3\u53ef\u4ee5\u7528 Enum \u6765\u5305\u88c5\u8fd9\u4e9b\u5185\u5bb9
    \u5982\u679c\u786c\u662f\u8981\u7528 null\uff0c\u6211\u5efa\u8bae\u628a null \u7684\u5904\u7406\u548c\u5176\u4ed6\u5904\u7406\u5206\u5f00\u3002\u5c3d\u91cf\u4e0d\u8981\u7528\u4e09\u5143\u8868\u8fbe\u5f0f\uff0c\u8fd9\u79cd\u4e1c\u897f\u6bd4\u8f83\u53cd\u4eba\u7c7b\uff0c\u5199\u8d77\u6765\u5f88\u723d\uff0c\u770b\u8d77\u6765\u4e00\u5934\u5305\u3002
    \u4f60\u8fd9\u79cd\u60c5\u51b5\u53ef\u4ee5\u5199\u4e2a\u51fd\u6570 getCodeMeaning(Integer code) {
     if (code == null) {
     return null;
     } else if (code == 1) {
     ******
    }
    \u4ee3\u7801\u5728\u53ef\u8bfb\u53ef\u7ef4\u62a4\u6027\u9762\u524d\uff0c\u7b80\u6d01\u6027\u53ef\u4ee5\u8981\u6c42\u4f4e\u4e00\u4e9b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : luozic <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5982\u679c java \u6709 pattern match \u5c31\u53ef\u4ee5\u73a9\u4f18\u96c5\uff1b\u4f46\u662f Java \u6ca1\u6709\uff0c\u6240\u4ee5\uff0c\u7406\u667a\u4e00\u70b9\uff0c\u7528\u8868\u9a71\u52a8\u53bb\u7cca\u5f04\u7b97\u4e86\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : redford42 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u524d\u51e0\u5929\u770b\u5230\u4e00\u4e2a java8 \u7684 optional
    \u4f46\u5176\u5b9e\u6211\u6ca1\u770b\u592a\u660e\u767d…                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : loryyang <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @loryyang #45 \u53e6\u5916\u8fd8\u6709\u4e00\u4e2a\u907f\u514d\u9b54\u6cd5\u503c\uff0c\u524d\u9762\u4e5f\u597d\u591a\u4eba\u63d0\u4e86\u3002\u5bf9\u4e8e\u8fd9\u4e00\u70b9\uff0c\u6211\u662f\u89c9\u5f97\uff0c\u4f60\u8003\u8651\u4e00\u4e0b\u662f\u5426\u6709\u5fc5\u8981\u505a\u3002\u4f60\u8fd9\u79cd case\uff0c\u76f4\u63a5\u7528\u4e00\u4e2a ImmutableMap \u597d\u4e86\uff0c\u8fd9\u6837\u53ef\u4ee5\u53d8\u6210\uff1a
    ImmutableMap.<Integer, String>builder().put(1, “”).put(2, “”).build()
    \u7136\u540e getCodeMeaning \u51fd\u6570\u91cc\u9762\u53d8\u6210
    if (code == null) {
    return null;
    }
    if (code in immutableMap) {
    return immutableMap.get(code);
    }
    else {
    return ***;
    }<\/p>\n
    \u56de\u5934\u770b\u4e00\u4e0b\uff0c\u8fd8\u662f null \u592a\u591a\u4e86\uff0cnull \u8fd9\u4e1c\u897f\u8fd8\u662f\u4e0d\u8981\u5728\u6b63\u5e38\u6d41\u7a0b\u4e2d\u51fa\u73b0\u5427                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : nekoneko <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @redford42 #47 \u611f\u89c9 optional \u5c31\u662f\u5a4a\u5b50\u7acb\u724c\u574a                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : godoway <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @nekoneko 
    @redford42 
    \u8fd9\u5176\u5b9e\u662f\u8bed\u6cd5\u4e0a\u63d0\u9192\u4f60\u68c0\u6d4b\u7a7a\u5b89\u5168\uff0c\u4f8b\u5982\u6709\u4e2a\u63a5\u53e3\u5165\u53c2 optional\uff0c\u4f60\u5c31\u77e5\u9053\u8fd9\u91cc\u53ef\u80fd\u4e3a\u7a7a\uff0c\u5165\u53c2\u4e00\u4e2a\u5bf9\u8c61\u6709\u53ef\u80fd\u4f60\u5c31\u5fd8\u4e86\u68c0\u6d4b\u975e\u7a7a                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : godloveplay <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4f60\u5199\u7684\u4ee3\u7801\u662f\u7ed9\u522b\u4eba\u770b\u7684\u3002 \u8bf7\u4f60\u7ad9\u5728\u522b\u4eba\u7684\u89d2\u5ea6\u601d\u8003\u4e00\u4e0b\uff0c\u770b\u5230\u8fd9\u4e2a\u4ee3\u7801\u7684\u5fc3\u60c5                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : oneisall8955 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @nekoneko \u6df1\u5c42\u5d4c\u5957\u83b7\u53d6\u503c\uff0c\u4e00\u76f4\u5224\u65ad\u975e\u7a7a\u5f88\u5570\u55e6\uff0cOptional \u53ef\u4ee5\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : winiex <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6c38\u8fdc\u4e0d\u8981\u5d4c\u5957\u591a\u5c42\u4e09\u5143\u8868\u8fbe\u5f0f\uff0c\u4e09\u5143\u8868\u8fbe\u5f0f\u5f53\u4e14\u4ec5\u5f53\u53ea\u6709\u4e00\u5c42\u903b\u8f91\u5224\u65ad\u65f6\u624d\u53ef\u4ee5\u4f7f\u7528\u3002\u5176\u5b83\u60c5\u51b5\u4e00\u5f8b\u7528 if else \u8001\u5b9e\u5730\u5199\u3002\u6211\u751a\u81f3\u8fde\u4e00\u5c42\u903b\u8f91\u5224\u65ad\u90fd\u60f3\u5f3a\u5236\u53ea\u80fd\u7528 if else\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : brucefu <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @micean \u80fd\u8ba9\u522b\u4eba\u4e00\u79d2\u5c31\u770b\u61c2\u7684\u4e1c\u897f\uff0c\u5c31\u4e0d\u8981\u641e\u6210\u4e24\u79d2                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : micean <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @brucefu <\/p>\n
    code == null ? null :
    code == 1 ? “\u4f60\u597d” :
    code == 2 ? “\u4f60\u597d\u597d” :
    code == 3 ? “\u4f60\u597d\u597d\u597d” : 
    “\u5176\u4ed6”;<\/p>\n
    \u8fd9\u4e0d\u5c31\u662f\u4e00\u4e2a\u7b80\u6613\u79d2\u61c2\u7684 switch\uff0c\u4e0a\u5176\u4ed6\u4ee3\u7801\u4e5f\u505a\u4e0d\u5230\u8fd9\u4e48\u5de5\u6574                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : micean <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u53e6\u5916\u5d4c\u5957\u7684\u4e09\u5143\u8fd8\u53ef\u4ee5\u8f7b\u8f7b\u677e\u677e\u7ed9 final \u4fee\u9970\u7684\u8d4b\u503c<\/p>\n
    final String name = <\/p>\n
    code == null ? “” :
    code == 1 ? “\u4f60\u597d” :
    code == 2 ? “\u4f60\u597d\u597d” :
    code == 3 ? “\u4f60\u597d\u597d\u597d” : 
    “\u5176\u4ed6”;                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : secondwtq <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8fd9\u4e0d\u5c31\u662f\u4e00\u4e2a Maybe Integer \u89e3\u51b3\u7684\u95ee\u9898 … \u641e\u8fd9\u4e48\u590d\u6742                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
    Java :\u5982\u4f55\u5904\u7406\u7a7a\u6307\u9488\uff1f \u8cc7\u6df1…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/104135"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=104135"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/104135\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=104135"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=104135"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=104135"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}