java正则学习
更新日期:
正则表达式
用于操作字符串的数据
1 2 3 | // 定义一个功能对QQ号进行校验
// 长度 5-15, 只能是数字, 0不能开头
boolean match = "938393".match("[1-9][0-9]{4,14}");
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常见规则
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | Character classes [abc] a, b, or c (simple class) [^abc] Any character except a, b, or c (negation) [a-zA-Z] a through z or A through Z, inclusive (range) [a-d[m-p]] a through d, or m through p: [a-dm-p] (union) [a-z&&[def]] d, e, or f (intersection) [a-z&&[^bc]] a through z, except for b and c: [ad-z] (subtraction) [a-z&&[^m-p]] a through z, and not m through p: [a-lq-z](subtraction) Predefined character classes . Any character (may or may not match line terminators) \d A digit: [0-9] \D A non-digit: [^0-9] \s A whitespace character: [ \t\n\x0B\f\r] \S A non-whitespace character: [^\s] \w A word character: [a-zA-Z_0-9] \W A non-word character: [^\w] Boundary matchers ^ The beginning of a line $ The end of a line \b A word boundary \B A non-word boundary Greedy quantifiers 贪懒 X? X, once or not at all X* X, zero or more times X+ X, one or more times X{n} X, exactly n times X{n,} X, at least n times X{n,m} X, at least n but not more than m times Reluctant quantifiers X?? X, once or not at all X*? X, zero or more times X+? X, one or more times X{n}? X, exactly n times X{n,}? X, at least n times X{n,m}? X, at least n but not more than m times |
匹配
"String".matches(regex)
切割
1 2 3 | String[] sep = str.split("\\s"); str = "zhangaaaaaaaaboccccccshen" String[] sep = str.split("(.)\\1+"); // 组 > zhang bo shen |
组
((A)(B(C))) 从左括号开始,第一个括号就是第一组, 第二个括号就是第二组
替换
1 2 3 4 5 6 | str = "zhangaaaaaaaaboccccccshen" // 叠词替换成一个 str.replaceAll("(.)\\1+", "$1"); // zhangabocshen str = "15800001111"; str.replaceAll("(\\d{3})\\d{4}(\\d{3})", "$1****$2"); |
获取
java.util.regex.Pattern: 正则表达式的对象形式
1 2 3 4 5 6 7 8 9 10 11 | // 将正则封装成对象 Pattern p = Pattern.compile("a*b"); // 通过正则对象的获取匹配器对象 Matcher m = p.matcher("aaaab"); // 使用Matcher对象对字符串进行操作 boolean b = m.matches(); while(m.find()){ m.group(); // 获取匹配的子序列 m.start(); // index of start m.end(); } |