{"id":1100,"date":"2022-10-23T22:51:10","date_gmt":"2022-10-23T14:51:10","guid":{"rendered":"https:\/\/qaqaq.top\/?p=1100"},"modified":"2022-11-27T12:39:50","modified_gmt":"2022-11-27T04:39:50","slug":"%e5%b8%b8%e7%94%a8%e7%b1%bb-%e8%a7%a3%e5%86%b3%e4%b8%80%e4%b8%aa%e6%8b%bc%e6%8e%a5%e9%97%ae%e9%a2%98%e3%80%81stringbuffer%e7%9a%84%e6%ba%90%e7%a0%81%e5%88%86%e6%9e%90%e3%80%81stringbuffer%e4%b8%ad","status":"publish","type":"post","link":"https:\/\/qaqaq.top\/?p=1100","title":{"rendered":"\u5e38\u7528\u7c7b-\u89e3\u51b3\u4e00\u4e2a\u62fc\u63a5\u95ee\u9898\u3001StringBuffer\u7684\u6e90\u7801\u5206\u6790\u3001StringBuffer\u4e2d\u7684\u5e38\u7528\u65b9\u6cd5\u3001String\u3001StringBuffer\u3001StringBuilder\u6548\u7387\u5bf9\u6bd4"},"content":{"rendered":"\n<pre class=\"wp-block-code\"><code>package top.qaqaq.java.P465;\r\n\r\nimport org.junit.jupiter.api.Test;\r\n\r\n\/**\r\n * \u5173\u4e8eStringBuffer\u548cStringBuilder\u7684\u4f7f\u7528\r\n *\r\n * @author RichieZhang\r\n * @create 2022-10-22 \u4e0b\u5348 7:05\r\n *\/\r\npublic class StringBufferBuilderTest {\r\n\r\n    \/*\r\n    \u5bf9\u6bd4String\u3001StringBuffer\u3001StringBuilder\u4e09\u8005\u7684\u6548\u7387\uff1a\r\n    \u4ece\u9ad8\u5230\u4f4e\u6392\u5217\uff1aStringBuilder > StringBuffer > String\r\n     *\/\r\n    @Test\r\n    public void test3() {\r\n        \/\/\u521d\u59cb\u8bbe\u7f6e\r\n        long startTime = 0L;\r\n        long endTime = 0L;\r\n        String text\r\n                = \"\";\r\n        StringBuffer buffer\r\n                = new StringBuffer(\"\");\r\n        StringBuilder builder\r\n                = new StringBuilder(\"\");\r\n        \/\/\u5f00\u59cb\u5bf9\u6bd4\r\n        startTime = System.currentTimeMillis();\r\n        for (int i = 0; i &lt; 20000; i++) {\r\n            buffer.append(String.valueOf(i));\r\n        }\r\n        endTime = System.currentTimeMillis();\r\n        System.out.println(\"StringBuffer\u7684\u6267\u884c\u65f6\u95f4\uff1a\" + (endTime - startTime));\r\n        startTime = System.currentTimeMillis();\r\n        for (int i = 0; i &lt; 20000; i++) {\r\n            builder.append(String.valueOf(i));\r\n        }\r\n        endTime = System.currentTimeMillis();\r\n        System.out.println(\"StringBuilder\u7684\u6267\u884c\u65f6\u95f4\uff1a\" + (endTime - startTime));\r\n        startTime = System.currentTimeMillis();\r\n        for (int i = 0; i &lt; 20000; i++) {\r\n            text\r\n                    = text + i;\r\n        }\r\n        endTime = System.currentTimeMillis();\r\n        System.out.println(\"String\u7684\u6267\u884c\u65f6\u95f4\uff1a\" + (endTime - startTime));\r\n    }\r\n\r\n    \/*\r\n    StringBuffer\u7684\u5e38\u7528\u65b9\u6cd5\uff1a\r\n    StringBuffer append(xxx)\uff1a\u63d0\u4f9b\u4e86\u5f88\u591a\u7684append()\u65b9\u6cd5\uff0c\u7528\u4e8e\u8fdb\u884c\u5b57\u7b26\u4e32\u62fc\u63a5\r\n    StringBuffer delete(int start,int end)\uff1a\u5220\u9664\u6307\u5b9a\u4f4d\u7f6e\u7684\u5185\u5bb9\r\n    StringBuffer replace(int start, int end, String str)\uff1a\u628a&#91;start,end)\u4f4d\u7f6e\u66ff\u6362\u4e3astr\r\n    StringBuffer insert(int offset, xxx)\uff1a\u5728\u6307\u5b9a\u4f4d\u7f6e\u63d2\u5165xxx\r\n    StringBuffer reverse() \uff1a\u628a\u5f53\u524d\u5b57\u7b26\u5e8f\u5217\u9006\u8f6c\r\n    public int indexOf(String str)\r\n    public String substring(int start,int end):\u8fd4\u56de\u4e00\u4e2a\u4ecestart\u5f00\u59cb\u5230end\u7d22\u5f15\u7ed3\u675f\u7684\u5de6\u95ed\u53f3\u5f00\u533a\u95f4\u7684\u5b50\u5b57\u7b26\u4e32\r\n    public int length()\r\n    public char charAt(int n )\r\n    public void setCharAt(int n ,char ch)\r\n\r\n            \u603b\u7ed3\uff1a\r\n            \u589e\uff1aappend(xxx)\r\n            \u5220\uff1adelete(int start, int end)\r\n            \u6539\uff1asetCharAt(int n, char ch) \/ replace(int start, int end. String str)\r\n            \u67e5\uff1acharAt(int n)\r\n            \u63d2\uff1ainsert(int offset, xxx)\r\n            \u957f\u5ea6\uff1alength();\r\n            *\u904d\u5386\uff1afor() + charAt() \/toString()\r\n     *\/\r\n\r\n    @Test\r\n    public void test2() {\r\n        StringBuffer s1 = new StringBuffer(\"abc\");\r\n        s1.append(1);\r\n        s1.append('1');\r\n        System.out.println(s1);\r\n\/\/        s1.delete(2,4);\r\n\/\/        s1.replace(2,4,\"hello\");\r\n\/\/        s1.insert(2,false);\r\n\/\/        s1.reverse();\r\n        String s2 = s1.substring(1, 3);\r\n        System.out.println(s1);\r\n        System.out.println(s1.length());\r\n        System.out.println(s2);\r\n\r\n    }\r\n\r\n    \/*\r\n    String\u3001StringBuffer\u3001StringBuilder\u4e09\u8005\u7684\u5f02\u540c\uff1f\r\n    String:\u4e0d\u53ef\u53d8\u7684\u5b57\u7b26\u5e8f\u5217; \u5e95\u5c42\u4f7f\u7528char&#91;]\u5b58\u50a8\r\n    StringBuffer:\u53ef\u53d8\u7684\u5b57\u7b26\u5e8f\u5217; \u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u6548\u7387\u4f4e\uff1b\r\n    StringBuilder:\u53ef\u53d8\u7684\u5b57\u7b26\u5e8f\u5217; jdk5.0\u65b0\u589e\u7684\uff0c\u7ebf\u7a0b\u4e0d\u5b89\u5168\u7684\uff0c\u6548\u7387\u9ad8;\r\n\r\n    \u6ce8\u610f\uff1a\u4ecejdk1.9\u5f00\u59cb \u5e95\u5c42\u4f7f\u7528byte&#91;]\u6570\u7ec4\u8fdb\u884c\u5b58\u50a8\r\n\r\n    \u6e90\u7801\u5206\u6790\uff1a\r\n    String str = new String();\/\/char&#91;] value = new char&#91;0];\r\n    String str1 = new String(\"abc\");\/\/char&#91;] value = new char&#91;]{'a','b','c'};\r\n\r\n    StringBuffer sb1 = new StringBuffer();\/\/char&#91;] value = new char&#91;16];\u5e95\u5c42\u521b\u5efa\u4e86\u4e00\u4e2a\u957f\u5ea6\u662f16\u7684\u6570\u7ec4\u3002\r\n    System.out.println(sb1.length());\/\/\r\n    sb1.append('a');\/\/value&#91;0] = 'a';\r\n    sb1.append('b');\/\/value&#91;1] = 'b';\r\n\r\n    StringBuffer sb2 = new StringBuffer(\"abc\");\/\/char&#91;] value = new char&#91;\"abc\".length() + 16];\r\n\r\n    \/\/\u95ee\u98981. System.out.println(sb2.length());\/\/3\r\n    \/\/\u95ee\u98982. \u6269\u5bb9\u95ee\u9898\u3002\u5982\u679c\u8981\u6dfb\u52a0\u7684\u6570\u636e\u5e95\u5c42\u6570\u7ec4\u76db\u4e0d\u4e0b\u4e86\uff0c\u90a3\u5c31\u9700\u8981\u6269\u5bb9\u5e95\u5c42\u7684\u6570\u7ec4\u3002\r\n                \u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u6269\u5bb9\u4e3a\u539f\u6765\u5bb9\u91cf\u76842\u500d + 2\uff0c\u540c\u65f6\u5c06\u539f\u6709\u6570\u7ec4\u4e2d\u7684\u5143\u7d20\u590d\u5236\u5230\u65b0\u7684\u6570\u7ec4\u4e2d\u3002\r\n\r\n                \u6307\u5bfc\u610f\u4e49\uff1a\u5f00\u53d1\u4e2d\u5efa\u8bae\u5927\u5bb6\u4f7f\u7528StringBuffer(int capacity) \u6216 Stringbuilder(int capacity)\r\n\r\n     *\/\r\n\r\n    @Test\r\n    public void test1() {\r\n        StringBuffer sb1 = new StringBuffer(\"abc\");\r\n        sb1.setCharAt(0, 'm');\r\n        System.out.println(sb1);\r\n\r\n        StringBuffer sb2 = new StringBuffer();\r\n        System.out.println(sb2.length());\/\/0\r\n\r\n    }\r\n}\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[46],"class_list":["post-1100","post","type-post","status-publish","format-standard","hentry","category-java-code","tag-java"],"_links":{"self":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/1100"}],"collection":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1100"}],"version-history":[{"count":1,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/1100\/revisions"}],"predecessor-version":[{"id":1101,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/1100\/revisions\/1101"}],"wp:attachment":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1100"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1100"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1100"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}