Pattern类,Matcher类

目录

1 Pattern类

2 Matcher类

2.1 matchers( )和 lookingAt( )

2.2 find( ),groupCount( )和group( )

2.3 start( )和end( )

 2.4 replaceFirst( )和replaceAll( )

        在进行正则匹配时,"正则字符串"会被编译成Pattern对象保存在内存中,以"待匹配字符串"作为参数通过Pattern对象创建出Matcher对象,然后对匹配结果做针对性操作

1 Pattern类

java.util.regex.Pattern

Pattern pattern = Pattern.compile("\\d*");

1.  
   Matcher matcher1 = pattern.matcher("abc456");
2.  
   Matcher matcher2 = pattern.matcher("123456");
3.  
   Arrays.toString(pattern.split("12ab33db56cf")); //返回[, ab, db, cf]

如果一个Pattern对象只用一次,则可以使用Pattern的静态方法matchs( )   String类的matchs( )方法本质就是调用Pattern类的matchs( )方法

boolean flag = Pattern.matches("\\d*", "123456");

2 Matcher类

java.util.regex.Matcher

2.1 matchers( )和 lookingAt( )

1.  
   Pattern pattern = Pattern.compile("\\d ");
2.  
   Matcher matcher = pattern.matcher("123abc");
3.  
   matcher.matches(); //返回false
4.  
   matcher.lookingAt(); //返回true

2.2 find( ),groupCount( )和group( )

1.  
   Pattern pattern = Pattern.compile("(\\d{3})-(\\d{7})");
2.  
   Matcher mc = pattern.matcher("728-4765164 520-7758258");
3.  
   while (mc.find()) {
4.  
   System.out.println("分组的个数有：" mc.groupCount());
5.  
   for (int i = 0; i <= mc.groupCount(); i ) {
6.  
   System.out.println("第" i "个分组为：" mc.group(i));
7.  
   }
8.  
   }
9.  
    
10.  
    //分组的个数有：2
11.  
    //第0个分组为：728-4765164
12.  
    //第1个分组为：728
13.  
    //第2个分组为：4765164
14.  
     
15.  
    //分组的个数有：2
16.  
    //第0个分组为：520-7758258
17.  
    //第1个分组为：520
18.  
    //第2个分组为：7758258

2.3 start( )和end( )

1.  
   Pattern pattern = Pattern.compile("[a-z] ");
2.  
   Matcher matcher = pattern.matcher("123abc456def789");
3.  
   while (matcher.find()) {
4.  
   System.out.println("匹配子串" matcher.group() "开始于" matcher.start() "结束于" matcher.end());
5.  
   //匹配子串abc开始于3结束于6
6.  
   //匹配子串def开始于9结束于12
7.  
   }

 2.4 replaceFirst( )和replaceAll( )

1.  
   Pattern pattern = Pattern.compile("\\d ");
2.  
   Matcher matcher = pattern.matcher("12ab33db56cf");
3.  
   matcher.replaceFirst("换"); //换ab33db56cf
4.  
   matcher.replaceAll("换"); //换ab换db换cf

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