{"id":219,"date":"2025-12-23T14:40:24","date_gmt":"2025-12-23T14:40:24","guid":{"rendered":"https:\/\/hyc.eshachem.com\/program\/?p=219"},"modified":"2025-12-23T14:41:08","modified_gmt":"2025-12-23T14:41:08","slug":"%e6%b3%9b%e5%9e%8b%e7%89%a9%e4%bb%b6","status":"publish","type":"post","link":"https:\/\/hyc.eshachem.com\/program\/%e6%b3%9b%e5%9e%8b%e7%89%a9%e4%bb%b6\/","title":{"rendered":"JAVA – \u6cdb\u578b\u7269\u4ef6"},"content":{"rendered":"\n

Integer \u985e\u5225<\/h2>\n\n\n\n

Integer.parseInt(a[0])<\/strong> \u5b57\u4e32\u8f49\u6578\u5b57<\/p>\n\n\n\n

Integer.max<\/em>(x,y)<\/p>\n\n\n\n

\u6bd4\u8f03x , y \u4e26\u56de\u50b3\u8f03\u5927\u8005\u4e4b\u503c<\/p>\n\n\n\n

int x = 20 , y = 10;\nstem.out.println(Integer.max(x,y));\/\/ 20\n\/\/ \u88dc\u5145Math.max()\u4e5f\u6709\u540c\u6548\u679c\nSystem.out.println(Math.max(x,y));\/\/ 20\n<\/code><\/pre>\n\n\n\n
Integer.compare(x, y)<\/p>\n\n\n\n
\u6bd4\u8f03\u5169\u500b int \u503c\uff0c\u82e5 x < y \u56de\u50b3 -1\uff0c\u82e5 x == y \u56de\u50b3 0\uff0c\u82e5 x > y \u56de\u50b3 1\u3002<\/p>\n\n\n\n
Integer x = 10 , y = 20;\nSystem.out.println(Integer.compare(x, y));\/\/-1\n<\/code><\/pre>\n\n\n\n
Integer.signum(x)<\/p>\n\n\n\n
\u8fd4\u56de\u6574\u6578\u7684\u7b26\u865f\u51fd\u6578\uff0c\u82e5 i \u70ba\u8ca0\u56de\u50b3 -1\uff0c\u70ba 0 \u56de\u50b3 0\uff0c\u70ba\u6b63\u56de\u50b3 1\u3002<\/p>\n\n\n\n
int x = -20;\nSystem.out.println(Integer.signum(x));\/\/-1\n\/\/ \u88dc\u5145Math.signum()\u4e5f\u6709\u540c\u6548\u679c\u4f46\u6703\u8b8a\u6210\u5c0f\u6578\u9ede\nSystem.out.println(Math.signum(x));\/\/ -1.0\n<\/code><\/pre>\n\n\n\n
Integer.toBinaryString(x)<\/p>\n\n\n\n
\u5c07x\u8f49\u70ba\u4e8c\u9032\u5236<\/p>\n\n\n\n
int x = 10;\nSystem.out.println(Integer.toBinaryString(x));\/\/1010\n<\/code><\/pre>\n\n\n\n
\u4e8c\u9032\u5236\u8f49\u5341\u9032\u5236 Integer.*parseInt*(\"1010\", 2);<\/code> \/\/ 10<\/p>\n\n\n\n
String \u985e\u5225<\/h2>\n\n\n\n
string \u662f\u4e0d\u53ef\u8b8a\u7684 \u6240\u4ee5\u8981\u4fee\u6539\u5b57\u4e32\u8981\u4f7f\u7528stringBuffer\u985e\u5225\uff08\u5f8c\u9762\u6703\u8aaa\u5230\uff09<\/p>\n\n\n\n
equals()<\/p>\n\n\n\n
\u662f\u5426\u76f8\u7b49<\/p>\n\n\n\n
\/\/ ex \u5224\u65b7\u5169\u8f38\u5165\u662f\u5426\u76f8\u7b49\nScanner sc = new Scanner(System.in);\nString q = sc.nextLine();\nString r = sc.nextLine();\nif (r.equals(q)){\n    System.out.println(\"True\");\n}else{\n    System.out.println(\"False\");\n}\n<\/code><\/pre>\n\n\n\n
toUpperCase() & toLowerCase()<\/p>\n\n\n\n
    \n
  • toUpperCase()<\/code><\/strong>\uff1a\u5c07\u5b57\u4e32\u8f49\u63db\u70ba\u5927\u5beb\u3002<\/li>\n\n\n\n
  • toLowerCase()<\/code><\/strong>\uff1a\u5c07\u5b57\u4e32\u8f49\u63db\u70ba\u5c0f\u5beb\u3002<\/li>\n<\/ul>\n\n\n\n
    String s = \"Hello World\";\nSystem.out.println(s.toUpperCase());  \/\/ \"HELLO WORLD\"\nSystem.out.println(s.toLowerCase());  \/\/ \"hello world\"\n<\/code><\/pre>\n\n\n\n
    strip()<\/p>\n\n\n\n
    \u79fb\u9664\u5b57\u4e32\u524d\u5f8c\u7684\u7a7a\u767d\u5b57\u7b26\u3002<\/p>\n\n\n\n
    String s = \"   Hello World   \";\nSystem.out.println(s.strip());  \/\/ \"Hello World\"\n<\/code><\/pre>\n\n\n\n
    replace() – \u66ff\u63db\u5168\u90e8<\/p>\n\n\n\n
    replace(char oldChar, char newChar)<\/code><\/strong>\uff1a\u66ff\u63db\u5b57\u4e32\u4e2d\u7684\u6307\u5b9a\u5b57\u7b26\u3002<\/p>\n\n\n\n
    String s = \"Hello World\";\nSystem.out.println(s.replace('o', 'a'));\n\/\/ \"Hella Warld\"\n<\/code><\/pre>\n\n\n\n
    split()<\/p>\n\n\n\n
    \u6839\u64da\u6307\u5b9a\u7684\u5206\u9694\u7b26\u5c07\u5b57\u4e32\u62c6\u5206\u6210\u9663\u5217\u3002<\/p>\n\n\n\n
    String s = \"apple,banana,orange\";\nString[] fruits = s.split(\",\");\nfor (String fruit : fruits) {\n    System.out.println(fruit);\n}\n\/\/ \u8f38\u51fa\uff1a\n\/\/ apple\n\/\/ banana\n\/\/ orange\n<\/code><\/pre>\n\n\n\n
    contains() – \u662f\u5426\u5305\u542b\u5b50\u5b57\u4e32<\/p>\n\n\n\n
    \u6aa2\u67e5\u5b57\u4e32\u4e2d\u662f\u5426\u5305\u542b\u6307\u5b9a\u7684\u5b50\u5b57\u4e32<\/p>\n\n\n\n
    String s = \"Hello WORLD\";\nSystem.out.println(s.contains(\"WORLD\"));  \/\/ true\nSystem.out.println(s.contains(\"world\"));  \/\/ false\n<\/code><\/pre>\n\n\n\n
    public class StringStaticMethods {\n    public static void main(String[] args) {\n        \n        \/\/ 1. String.format() \u7528\u65bc\u683c\u5f0f\u5316\u5b57\u4e32\n        String name = \"Alice\";\n        int age = 30;\n        System.out.println(String.format(\"\u59d3\u540d: %s, \u5e74\u9f61: %d\", name, age);); \/\/ \u59d3\u540d: Alice, \u5e74\u9f61: 30\n\n        \/\/ 2. String.join() = join() in python\n        System.out.println(String.join(\", \", \"\u860b\u679c\", \"\u9999\u8549\", \"\u6a58\u5b50\")); \/\/ \u860b\u679c, \u9999\u8549, \u6a58\u5b50\n\n<\/code><\/pre>\n\n\n\n
    StringBuffer \u985e\u5225<\/h1>\n\n\n\n
    Java \u4e2d\u7684\u4e00\u7a2e\u53ef\u8b8a\u7684\u5b57\u7b26\u4e32\u985e\uff0c\u7528\u4f86\u8655\u7406\u591a\u500b\u5b57\u7b26\u4e32\u7684\u62fc\u63a5\u3001\u63d2\u5165\u3001\u522a\u9664\u7b49\u64cd\u4f5c\u3002\u7576\u4f60\u5c0d StringBuffer<\/code> \u9032\u884c\u64cd\u4f5c\u6642\uff0c\u5b83\u4e0d\u6703\u5275\u5efa\u65b0\u7684\u5c0d\u8c61\uff0c\u800c\u662f\u76f4\u63a5\u5728\u539f\u672c\u7684\u5c0d\u8c61\u4e0a\u4fee\u6539\u3002<\/p>\n\n\n\n
    \u683c\u5f0f<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\u4f5c\u7528\u5c0d\u8c61).\u65b9\u6cd5()\n<\/code><\/pre>\n\n\n\n
    .\u65b9\u6cd5()<\/p>\n\n\n\n
    append<\/p>\n\n\n\n
    append(String str)<\/code><\/strong>\uff1a\u5c07\u6307\u5b9a\u7684\u5b57\u4e32\u8ffd\u52a0\u5230\u73fe\u6709\u5b57\u4e32\u7684\u672b\u5c3e\u3002<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\"Hello\").append(\" World\");\nSystem.out.println(sb); \/\/ \u7d50\u679c: \"Hello World\"\n<\/code><\/pre>\n\n\n\n
    insert – \u5728\u6307\u5b9a\u4f4d\u7f6e\u63d2\u5165<\/p>\n\n\n\n
    insert(int offset, String str)<\/code><\/strong>\uff1a\u5728\u6307\u5b9a\u4f4d\u7f6e\u63d2\u5165\u5b57\u4e32\u3002<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\"Hello\").insert(5, \" World\");\nSystem.out.println(sb); \/\/ \u7d50\u679c: \"Hello World\"\n<\/code><\/pre>\n\n\n\n
    delete<\/p>\n\n\n\n
    delete(int start, int end)<\/code><\/strong>\uff1a\u522a\u9664\u6307\u5b9a\u7bc4\u570d\u5167\u7684\u5b57\u5143\u3002<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\"Hello World\");\nsb.delete(5, 11); \/\/ \u7d50\u679c: \"Hello\"\n<\/code><\/pre>\n\n\n\n
    replace – \u6307\u5b9a\u7bc4\u570d\u7684\u66ff\u63db<\/p>\n\n\n\n
    replace(int start, int end, String str)<\/code><\/strong>\uff1a\u66ff\u63db\u6307\u5b9a\u7bc4\u570d\u5167\u7684\u5b57\u5143\u70ba\u65b0\u7684\u5b57\u4e32\u3002<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\"Hello World\").replace(6, 11, \"Java\");\nSystem.out.println(sb); \/\/ \u7d50\u679c: \"Hello Java\"\n<\/code><\/pre>\n\n\n\n
    reverse<\/p>\n\n\n\n
    reverse()<\/code><\/strong>\uff1a\u53cd\u8f49\u5b57\u4e32\u3002<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\"Hello\").reverse();\nSystem.out.println(sb);\/\/ \u7d50\u679c: \"olleH\"\n<\/code><\/pre>\n\n\n\n
    charAt – \u8fd4\u56de\u5c0d\u61c9index\u4e4b\u5b57\u6bcd<\/p>\n\n\n\n
    charAt(int index)<\/code><\/strong>\uff1a\u8fd4\u56de\u6307\u5b9a\u7d22\u5f15\u8655\u7684\u5b57\u5143\u3002<\/p>\n\n\n\n
    StringBuffer sb = new StringBuffer(\"Hello\");\nchar ch = sb.charAt(1); \/\/ \u7d50\u679c: 'e'\n<\/code><\/pre>\n\n\n\n
    !!\u6ce8\u610f<\/code><\/strong> StringBufer\u51fa\u4f86\u7684\u6771\u897f\u4e0d\u662f\u5b57\u4e32\uff0c\u82e5\u8981\u518d\u9032\u884c\u201d\u662f\u5426\u76f8\u7b49\u201d\u7b49\u7684\u201d\u5b57\u4e32\u9593\u7684\u52d5\u4f5c\u201d\u9700\u8981\u518d.toString()<\/p>\n\n\n\n
    \/\/ ex \u5224\u65b7\u662f\u4e0d\u662f\u56de\u6587\nScanner sc = new Scanner(System.in);\nString q = sc.nextLine();\nStringBuffer r = new StringBuffer(q).reverse();\nif (r.toString().equals(q)){ \/\/ \u8981.toString()\n    System.out.println(\"True\");\n}else{\n    System.out.println(\"False\");\n}\n<\/code><\/pre>\n\n\n\n
    \u6240\u4ee5\u4e5f\u53ef\u4ee5\u76f4\u63a5\u683c\u5f0f\u5beb\u9019\u6a23<\/p>\n\n\n\n
    String test = new StringBuffer(\u4f5c\u7528\u5c0d\u8c61).toString().\u65b9\u6cd5()\n<\/code><\/pre>\n\n\n\n
    \u5c07\u5b57\u4e32\u8f49\u70basb\u5f8c\u53cd\u8f49<\/p>\n\n\n\n
    String x = \"Hello World\";\n\/\/ \u5c07 String \u8f49\u63db\u70ba StringBuffer \u4e26\u53cd\u8f49\nStringBuffer sb = new StringBuffer(x).reverse();\n        \nString reversed = sb.toString(); \/\/ \u518d\u5c07 StringBuffer \u8f49\u56de String\nSystem.out.println(reversed); \/\/ \u8f38\u51fa\uff1adlroW olleH\n\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
    Integer \u985e\u5225 Integer.parseInt(a[0]) \u5b57\u4e32\u8f49\u6578\u5b57 Integer.max(x,y) \u6bd4\u8f03x , y \u4e26\u56de\u50b3\u8f03\u5927\u8005\u4e4b\u503c Integer.compare(x, […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19],"tags":[],"class_list":["post-219","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/posts\/219","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/comments?post=219"}],"version-history":[{"count":2,"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/posts\/219\/revisions"}],"predecessor-version":[{"id":221,"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/posts\/219\/revisions\/221"}],"wp:attachment":[{"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/media?parent=219"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/categories?post=219"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hyc.eshachem.com\/program\/wp-json\/wp\/v2\/tags?post=219"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}