Matcher start() end() group() groupCount()

Java正则表达式实战

最新推荐文章于 2025-10-18 15:45:54 发布

转载最新推荐文章于 2025-10-18 15:45:54 发布 · 827 阅读

本文通过具体示例介绍了Java中使用正则表达式的Matcher类的方法，包括如何获取匹配字符串的开始位置及匹配组数。并通过两个实例展示了Matcher类中start()与groupCount()方法的应用。

public int start() 这个方法返回了，Matcher所匹配的字符串在整个字符串的的开始下标：

下面我们看看一个小例子

public class MatcherStartExample{
  public static void main(String args[]){
      test();
  }
  public static void test(){

     //create a Matcher and use the Matcher.start() method
     String candidateString = "My name is Bond. James Bond.";
     String matchHelper[] =
      {"          ^","                      ^"};
     Pattern p = Pattern.compile("Bond");
     Matcher matcher = p.matcher(candidateString);
     //Find the starting point of the first 'Bond'
      matcher.find();
      int startIndex = matcher.start();
      System.out.println(candidateString);
      System.out.println(matchHelper[0] + startIndex);
     //Find the starting point of the second 'Bond'
      matcher.find();
      int nextIndex = matcher.start();
      System.out.println(candidateString);
      System.out.println(matchHelper[1] + nextIndex);
}

输出结果：

My name is Bond. James Bond.

^11

My name is Bond. James Bond.

^23

我自己改了这个例子

import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class TestPatternAndMatcher3 {

    public static void test(){
        String candidateString = "My name is Bond. James Bond.";
        String matchHelper[] =  {"          ^", + 
                         "                      ^"};

        Pattern p = Pattern.compile("Bond");
        Matcher matcher = p.matcher(candidateString);

        matcher.find();
        int startIndex = matcher.start();
        System.out.println(candidateString);
        System.out.println(matchHelper[0] + startIndex);

        char[] al = candidateString.toCharArray();
        System.out.println("al[startIndex] : " + al[startIndex]);

        matcher.find();
        int nextIndex = matcher.start();
        System.out.println(candidateString);
        System.out.println(matchHelper[1] + nextIndex);

        char[] al2 = candidateString.toCharArray();
        System.out.println("al2[startIndex] : " + al2[startIndex]);
   }

public static void main(String[] args) {

    test();

}


}

</pre><pre class="java" name="code" style="color: rgb(102, 102, 102); background-color: rgb(255, 255, 255);">import java.util.regex.*;
public class MatcherGroupExample{
  public static void main(String args[]){
      test();
  }
  public static void test(){
      //create a Pattern
      Pattern p = Pattern.compile("Bond");
      //create a Matcher and use the Matcher.group() method
      String candidateString = "My name is Bond. James Bond.";
      Matcher matcher = p.matcher(candidateString);
      //extract the group
      matcher.find();
      System.out.println(matcher.group());
  }
}

public int groupCount()

这个方法返回了，正则表达式的匹配的组数。

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