{"id":1051,"date":"2026-03-20T20:47:51","date_gmt":"2026-03-20T12:47:51","guid":{"rendered":"https:\/\/yunyanglib.cn\/?p=1051"},"modified":"2026-03-20T20:47:51","modified_gmt":"2026-03-20T12:47:51","slug":"%e3%80%90java%e3%80%91%e5%ad%97%e7%ac%a6%e4%b8%b2%e6%8b%bc%e6%8e%a5%e5%ae%8c%e5%85%a8%e6%8c%87%e5%8d%97%ef%bc%9a%e4%bb%8e%e5%8e%9f%e7%90%86%e5%88%b0%e5%ae%9e%e6%88%98%e4%bc%98%e5%8c%96","status":"publish","type":"post","link":"https:\/\/yunyanglib.cn\/?p=1051","title":{"rendered":"\u3010Java\u3011\u5b57\u7b26\u4e32\u62fc\u63a5\u5b8c\u5168\u6307\u5357\uff1a\u4ece\u539f\u7406\u5230\u5b9e\u6218\u4f18\u5316"},"content":{"rendered":"\n

\u5927\u5bb6\u597d\uff0c\u6211\u662f\u4e91\u626c\uff5e \u5b57\u7b26\u4e32\u62fc\u63a5\u662f Java \u5f00\u53d1\u4e2d\u6700\u5e38\u7528\u7684\u64cd\u4f5c\u4e4b\u4e00\uff0c\u4f46\u5f88\u591a\u540c\u5b66\u53ef\u80fd\u6ca1\u610f\u8bc6\u5230\uff0c\u4e0d\u540c\u62fc\u63a5\u65b9\u5f0f\u7684\u6027\u80fd\u5dee\u5f02\u548c\u5e95\u5c42\u5b9e\u73b0\u5929\u5dee\u5730\u522b\u3002\u4eca\u5929\u5c31\u5e26\u5927\u5bb6\u6df1\u5165\u62c6\u89e3 5 \u79cd\u5e38\u7528\u7684\u5b57\u7b26\u4e32\u62fc\u63a5\u65b9\u6cd5\uff0c\u7ed3\u5408\u6e90\u7801\u548c\u5b9e\u6218\u573a\u666f\uff0c\u5e2e\u4f60\u907f\u5f00\u5751\u70b9\u3001\u9009\u5bf9\u65b9\u6848\uff01<\/p>\n\n\n\n

\u4e00\u3001+ \u53f7\u64cd\u4f5c\u7b26\uff1a\u8bed\u6cd5\u7cd6\u7684\u751c\u871c\u4e0e\u9677\u9631<\/h2>\n\n\n\n

\u6211\u4eec\u6700\u719f\u6089\u7684+<\/code>\u53f7\u62fc\u63a5\uff0c\u672c\u8d28\u662f Java \u7f16\u8bd1\u5668\u63d0\u4f9b\u7684\u8bed\u6cd5\u7cd6\u3002\u5148\u770b\u4e00\u4e2a\u76f4\u89c2\u793a\u4f8b\uff1a<\/p>\n\n\n\n

\/\/ \u539f\u4ee3\u7801\nString a = \"Hello\";\nString b = \"World\";\nString c = a + b;\n\n\/\/ \u7f16\u8bd1\u540e\u5b9e\u9645\u6267\u884c\uff08\u53cd\u7f16\u8bd1class\u6587\u4ef6\uff09\nString a = \"Hello\";\nString b = \"World\";\nString c = new StringBuilder().append(a).append(b).toString();\n<\/code><\/pre>\n\n\n\n
\u5173\u952e\u7279\u6027\uff1a<\/h3>\n\n\n\n
    \n
  1. \u7f16\u8bd1\u671f\u4f18\u5316<\/strong>\uff1a\u5982\u679c\u62fc\u63a5\u7684\u662f\u7f16\u8bd1\u65f6\u5e38\u91cf\uff0c\u4f1a\u76f4\u63a5\u4f18\u5316\u4e3a\u5e38\u91cf\u5b57\u7b26\u4e32\uff1ajavaString d = 11 + \"\"; \/\/ \u7f16\u8bd1\u540e\u76f4\u63a5\u662f String d = \"11\";<\/code><\/li>\n\n\n\n
  2. \u5faa\u73af\u4e2d\u7684\u81f4\u547d\u95ee\u9898<\/strong>\uff1a\u5faa\u73af\u4f53\u5185\u4f7f\u7528+<\/code>\u53f7\u4f1a\u521b\u5efa\u5927\u91cfStringBuilder<\/code>\u5bf9\u8c61\uff0c\u5bfc\u81f4\u5185\u5b58\u6d6a\u8d39\u548c GC \u9891\u7e41\uff1a<\/li>\n<\/ol>\n\n\n\n
    \/\/ \u53cd\u9762\u793a\u4f8b\uff1a\u5faa\u73af\u4e2d\u6ee5\u7528+\u53f7\uff08\u6027\u80fd\u6781\u5dee\uff09\nString result = \"\";\nfor (int i = 0; i<1000; i++) {\n    result += i; \/\/ \u6bcf\u6b21\u5faa\u73af\u90fd\u65b0\u5efaStringBuilder\n}<\/code><\/pre>\n\n\n\n
    \u4e8c\u3001StringBuilder.append\uff1a\u5faa\u73af\u62fc\u63a5\u7684\u6700\u4f18\u89e3<\/h2>\n\n\n\n
    \u65e2\u7136+<\/code>\u53f7\u5728\u5faa\u73af\u4e2d\u4f1a\u521b\u5efa\u591a\u4e2aStringBuilder<\/code>\uff0c\u90a3\u76f4\u63a5\u624b\u52a8\u63a7\u5236StringBuilder<\/code>\u5b9e\u4f8b\u5373\u53ef\uff1a<\/p>\n\n\n\n
    \u6b63\u786e\u5199\u6cd5\uff1a<\/h3>\n\n\n\n
    \/\/ \u6b63\u9762\u793a\u4f8b\uff1a\u5faa\u73af\u5916\u521b\u5efaStringBuilder\nStringBuilder sb = new StringBuilder();\nfor (int i = 0; i< 1000; i++) {\n    sb.append(i); \/\/ \u590d\u7528\u540c\u4e00\u4e2a\u5bf9\u8c61\uff0c\u6027\u80fd\u62c9\u6ee1\n}\nString result = sb.toString();\n<\/code><\/pre>\n\n\n\n
    \u6e90\u7801\u6838\u5fc3\u903b\u8f91\uff08AbstractStringBuilder\uff09\uff1a<\/h3>\n\n\n\n
    \/\/ \u7b80\u5316\u6838\u5fc3\u6d41\u7a0b\npublic AbstractStringBuilder append(String str) {\n    if (str == null) return appendNull(); \/\/ null\u5904\u7406\u4e3a\"null\"\n    int len = str.length();\n    ensureCapacityInternal(count + len); \/\/ \u6570\u7ec4\u6269\u5bb9\u68c0\u67e5\n    str.getChars(0, len, value, count); \/\/ \u5b57\u7b26\u6570\u7ec4\u590d\u5236\n    count += len;\n    return this;\n}\n<\/code><\/pre>\n\n\n\n
    \u5173\u952e\u4f18\u5316\u70b9\uff1a<\/h3>\n\n\n\n
      \n
    • \u521d\u59cb\u5bb9\u91cf\uff1a\u9ed8\u8ba4 16 \u5b57\u7b26\uff0c\u53ef\u6307\u5b9a\u521d\u59cb\u5bb9\u91cf\u51cf\u5c11\u6269\u5bb9\u6b21\u6570\uff1anew StringBuilder(1024)<\/code><\/li>\n\n\n\n
    • \u7ebf\u7a0b\u4e0d\u5b89\u5168\uff1a\u5355\u7ebf\u7a0b\u573a\u666f\u4f7f\u7528\uff0c\u591a\u7ebf\u7a0b\u7528StringBuffer<\/code>\uff08\u6548\u7387\u8f83\u4f4e\uff09<\/li>\n<\/ul>\n\n\n\n
      \u4e09\u3001String.concat\uff1a\u7b80\u5355\u62fc\u63a5\u7684\u8f7b\u91cf\u9009\u62e9<\/h2>\n\n\n\n
      concat()<\/code>\u65b9\u6cd5\u662f String \u7c7b\u539f\u751f\u7684\u62fc\u63a5\u65b9\u5f0f\uff0c\u8bed\u6cd5\u7b80\u6d01\uff1a<\/p>\n\n\n\n
      \u4f7f\u7528\u793a\u4f8b\uff1a<\/h3>\n\n\n\n
      String a = \"Hello\";\nString b = \"World\";\nString c = a.concat(b); \/\/ \u7ed3\u679c\uff1a\"HelloWorld\"\n<\/code><\/pre>\n\n\n\n
      \u6e90\u7801\u6838\u5fc3\u7279\u6027\uff1a<\/h3>\n\n\n\n
      public String concat(String str) {\n    int otherLen = str.length();\n    if (otherLen == 0) {\n        return this;\n    }\n    int len = value.length;\n    char buf[] = Arrays.copyOf(value, len + otherLen);\n    str.getChars(buf, len);\n    return new String(buf, true);\n}<\/code><\/pre>\n\n\n\n
        \n
      1. \u7a7a\u5b57\u7b26\u4e32\u4f18\u5316\uff1a\u62fc\u63a5\u7a7a\u5b57\u7b26\u4e32\u65f6\u76f4\u63a5\u8fd4\u56de\u539f\u5bf9\u8c61\uff0c\u65e0\u9700\u521b\u5efa\u65b0\u5b57\u7b26\u4e32<\/li>\n\n\n\n
      2. null \u5904\u7406\uff1a\u9047\u5230 null \u4f1a\u629b\u51faNullPointerException<\/code>\uff08\u4e0e+<\/code>\u53f7\u7684 “null” \u5904\u7406\u4e0d\u540c\uff09\uff1a<\/li>\n<\/ol>\n\n\n\n
        \/\/ \u5bf9\u6bd4\u6d4b\u8bd5\nString e = null + \"test\"; \/\/ \u7ed3\u679c\uff1a\"nulltest\"\nString f = \"test\".concat(null); \/\/ \u629b\u51faNPE<\/code><\/pre>\n\n\n\n
           3. \u9002\u7528\u573a\u666f\uff1a\u4ec5\u9700\u62fc\u63a5 1-2 \u4e2a\u5b57\u7b26\u4e32\uff0c\u4e14\u786e\u5b9a\u65e0 null \u7684\u573a\u666f<\/p>\n\n\n\n
        \u56db\u3001String.join\uff1a\u5e26\u5206\u9694\u7b26\u7684\u4f18\u96c5\u62fc\u63a5<\/h2>\n\n\n\n
        Java 8 \u65b0\u589e\u7684String.join()<\/code>\u9759\u6001\u65b9\u6cd5\uff0c\u4e13\u4e3a\u591a\u5b57\u7b26\u4e32\u62fc\u63a5 + \u5206\u9694\u7b26\u8bbe\u8ba1\uff1a<\/p>\n\n\n\n
        \u57fa\u672c\u7528\u6cd5\uff1a<\/h3>\n\n\n\n
        \/\/ \u5206\u9694\u7b26 + \u53ef\u53d8\u53c2\u6570\nString names = String.join(\",\", \"\u5f20\u4e09\", \"\u674e\u56db\", \"\u738b\u4e94\");\nSystem.out.println(names); \/\/ \u8f93\u51fa\uff1a\"\u5f20\u4e09,\u674e\u56db,\u738b\u4e94\"\n\n\/\/ \u5206\u9694\u7b26 + \u96c6\u5408\nList<String> fruits = Arrays.asList(\"\u82f9\u679c\", \"\u9999\u8549\", \"\u6a59\u5b50\");\nString fruitStr = String.join(\"|\", fruits);\nSystem.out.println(fruitStr); \/\/ \u8f93\u51fa\uff1a\"\u82f9\u679c|\u9999\u8549|\u6a59\u5b50\"\n<\/code><\/pre>\n\n\n\n
        \u5e95\u5c42\u5b9e\u73b0\uff1a<\/h3>\n\n\n\n
        public static String join(CharSequence delimiter, CharSequence... elements) {\n    Objects.requireNonNull(delimiter);\n    Objects.requireNonNull(elements);\n    \/\/ Number of elements not likely worth Arrays.stream overhead.\n    StringJoiner joiner = new StringJoiner(delimiter);\n    for (CharSequence cs: elements) {\n        joiner.add(cs);\n    }\n    return joiner.toString();\n}<\/code><\/pre>\n\n\n\n
        \u5185\u90e8\u901a\u8fc7StringJoiner<\/code>\u5b9e\u73b0\uff0c\u81ea\u52a8\u5904\u7406\u5206\u9694\u7b26\uff0c\u907f\u514d\u624b\u52a8\u62fc\u63a5\u5206\u9694\u7b26\u7684\u5197\u4f59\u4ee3\u7801\u3002<\/p>\n\n\n\n
        \u4e94\u3001StringUtils.join\uff1a\u7a7a\u5b89\u5168\u7684\u5b9e\u7528\u5de5\u5177<\/h2>\n\n\n\n
        \u6765\u81ea org.apache.commons.lang3<\/code>\u7684StringUtils.join()<\/code>\uff0c\u89e3\u51b3\u4e86 null \u5904\u7406\u7684\u75db\u70b9\uff1a<\/p>\n\n\n\n
        \u6838\u5fc3\u4f18\u52bf\uff1a<\/h3>\n\n\n\n
        \/\/ \u81ea\u52a8\u5ffd\u7565null\uff0c\u65e0\u9700\u624b\u52a8\u5224\u7a7a\nString[] arr = {\"Java\", null, \"Python\", \"Go\"};\nString result = StringUtils.join(arr, \"-\");\nSystem.out.println(result); \/\/ \u8f93\u51fa\uff1a\"Java-Python-Go\"\n\n\/\/ \u96c6\u5408\u62fc\u63a5\u540c\u6837\u652f\u6301\nList<String> list = Arrays.asList(\"Spring\", null, \"MyBatis\");\nString listResult = StringUtils.join(list, \",\");\n<\/code><\/pre>\n\n\n\n
        \u5e95\u5c42\u903b\u8f91\uff1a<\/h3>\n\n\n\n
        public static String join(final Object[] array, String separator, final int startIndex, final int endIndex) {\n    if (array == null) {\n        return null;\n    }\n    if (separator == null) {\n        separator = EMPTY;\n    }\n\n    final StringBuilder buf = new StringBuilder(noOfItems * 16);\n\n    for (int i = startIndex; i < endIndex; i++) {\n        if (i > startIndex) {\n            buf.append(separator);\n        }\n        if (array[i] != null) {\n            buf.append(array[i]);\n        }\n    }\n    return buf.toString();\n}<\/code><\/pre>\n\n\n\n
        \u5185\u90e8\u4ecd\u4f7f\u7528StringBuilder<\/code>\u5b9e\u73b0\uff0c\u589e\u52a0\u4e86 null \u8fc7\u6ee4\u903b\u8f91\uff0c\u5f00\u53d1\u6548\u7387\u548c\u6027\u80fd\u517c\u987e\u3002<\/p>\n\n\n\n
        \u516d\u3001\u65b9\u6cd5\u5bf9\u6bd4\u4e0e\u573a\u666f\u9009\u62e9<\/h2>\n\n\n\n
        \u62fc\u63a5\u65b9\u5f0f<\/th>\u4f18\u70b9<\/th>\u7f3a\u70b9<\/th>\u9002\u7528\u573a\u666f<\/th><\/tr><\/thead>
        + \u53f7\u64cd\u4f5c\u7b26<\/td>\u8bed\u6cd5\u7b80\u6d01<\/td>\u5faa\u73af\u4e2d\u6027\u80fd\u5dee<\/td>\u5c11\u91cf\u5b57\u7b26\u4e32\u62fc\u63a5<\/td><\/tr>
        StringBuilder.append<\/td>\u6027\u80fd\u6700\u4f18<\/td>\u8bed\u6cd5\u7a0d\u7e41\u7410<\/td>\u5faa\u73af\u62fc\u63a5\u3001\u5927\u91cf\u5b57\u7b26\u4e32<\/td><\/tr>
        String.concat<\/td>\u8f7b\u91cf\u65e0\u989d\u5916\u4f9d\u8d56<\/td>\u4e0d\u652f\u6301 null\u3001\u591a\u5b57\u7b26\u4e32\u62fc\u63a5\u9ebb\u70e6<\/td>1-2 \u4e2a\u975e null \u5b57\u7b26\u4e32\u62fc\u63a5<\/td><\/tr>
        String.join<\/td>\u5206\u9694\u7b26\u4f18\u96c5\u5904\u7406<\/td>\u4e0d\u652f\u6301 null\uff08\u9700\u624b\u52a8\u8fc7\u6ee4\uff09<\/td>\u5e26\u5206\u9694\u7b26\u7684\u591a\u5b57\u7b26\u4e32\u62fc\u63a5<\/td><\/tr>
        StringUtils.join<\/td>\u7a7a\u5b89\u5168\u3001\u529f\u80fd\u5168\u9762<\/td>\u9700\u5f15\u5165\u7b2c\u4e09\u65b9\u4f9d\u8d56<\/td>\u9879\u76ee\u5df2\u4f9d\u8d56 Commons Lang3<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
        \u603b\u7ed3<\/h2>\n\n\n\n
          \n
        1. \u65e5\u5e38\u5f00\u53d1\u4e2d\uff0c\u5faa\u73af\u62fc\u63a5\u4f18\u5148\u7528StringBuilder.append<\/code>\uff0c\u8bb0\u5f97\u6307\u5b9a\u521d\u59cb\u5bb9\u91cf<\/li>\n\n\n\n
        2. \u5c11\u91cf\u5b57\u7b26\u4e32\u62fc\u63a5\u7528+<\/code>\u53f7\u5373\u53ef\uff0c\u4ee3\u7801\u7b80\u6d01\u6613\u8bfb<\/li>\n\n\n\n
        3. \u5e26\u5206\u9694\u7b26\u7684\u62fc\u63a5\u4f18\u5148\u7528String.join<\/code>\uff0c\u5e72\u51c0\u4f18\u96c5<\/li>\n\n\n\n
        4. \u6d89\u53ca null \u7684\u573a\u666f\u76f4\u63a5\u7528StringUtils.join<\/code>\uff0c\u907f\u514d\u7a7a\u6307\u9488\u8e29\u5751<\/li>\n<\/ol>\n\n\n\n
          \u5b57\u7b26\u4e32\u62fc\u63a5\u770b\u4f3c\u7b80\u5355\uff0c\u5b9e\u5219\u85cf\u7740\u4e0d\u5c11\u4f18\u5316\u7ec6\u8282\u3002\u9009\u62e9\u5408\u9002\u7684\u62fc\u63a5\u65b9\u5f0f\uff0c\u65e2\u80fd\u63d0\u5347\u4ee3\u7801\u6027\u80fd\uff0c\u4e5f\u80fd\u8ba9\u4ee3\u7801\u66f4\u5177\u53ef\u8bfb\u6027\u3002\u4f60\u5728\u9879\u76ee\u4e2d\u5e38\u7528\u54ea\u79cd\u62fc\u63a5\u65b9\u5f0f\uff1f\u6b22\u8fce\u5728\u8bc4\u8bba\u533a\u4ea4\u6d41\uff5e<\/p>\n","protected":false},"excerpt":{"rendered":"
          \u5927\u5bb6\u597d\uff0c\u6211\u662f\u4e91\u626c\uff5e \u5b57\u7b26\u4e32\u62fc\u63a5\u662f Java \u5f00\u53d1\u4e2d\u6700\u5e38\u7528\u7684\u64cd\u4f5c\u4e4b\u4e00\uff0c\u4f46\u5f88\u591a\u540c\u5b66\u53ef\u80fd\u6ca1\u610f\u8bc6\u5230\uff0c\u4e0d\u540c\u62fc\u63a5\u65b9\u5f0f\u7684\u6027\u80fd<\/p>\n
          \n\t\t\t\t Read More <\/span> <\/i><\/a>\n\t\t\t<\/div>\n","protected":false},"author":1,"featured_media":1054,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[15],"class_list":["post-1051","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-java"],"_links":{"self":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts\/1051","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1051"}],"version-history":[{"count":5,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts\/1051\/revisions"}],"predecessor-version":[{"id":1115,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/posts\/1051\/revisions\/1115"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=\/wp\/v2\/media\/1054"}],"wp:attachment":[{"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1051"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1051"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/yunyanglib.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1051"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}