Java 中的 Matcher group() 方法及示例

java.util.regex.Matcher 类表示执行各种匹配操作的引擎。此类没有构造函数，您可以使用 java.util.regex.Pattern 类的 matches() 方法创建/获取此类的对象。

这个 (Matcher) 类的group()方法在最后一次匹配期间返回匹配的输入子序列。

示例 1

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class GroupExample {
   public static void main(String[] args) {
      String str = "
This is an example HTML script "
         + "where every alternative word is bold. "
         + "It also contains italic words
";
      //Regular expression to match contents of the bold tags
      String regex = "(\S+)|(\S+)";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Matching the compiled pattern in the String
      Matcher matcher = pattern.matcher(str);
      while (matcher.find()) {
         System.out.println(matcher.group());
      }
   }
}

输出

is
example
script
every
word
bold
also
italic

此方法的另一个变体接受表示组的整数变量，其中捕获的组从 1（从左到右）开始索引。

示例 2

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class GroupTest {
   public static void main(String[] args) {
      String regex = "(.*)(\d+)(.*)";
      String input = "This is a sample Text, 1234, with numbers in between.";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Matching the compiled pattern in the String
      Matcher matcher = pattern.matcher(input);
      if(matcher.find()) {
         System.out.println("match: "+matcher.group(0));
         System.out.println("First group match: "+matcher.group(1));
         System.out.println("Second group match: "+matcher.group(2));
         System.out.println("Third group match: "+matcher.group(3));
      }
   }
}

输出

match: This is a sample Text, 1234, with numbers in between.
First group match: This is a sample Text, 123
Second group match: 4
Third group match: , with numbers in between.