Java中的 Matcher groupCount() 方法及示例

Matcher 类的groupCount()方法用于获取此匹配器模式中捕获组的数量。

句法：

public int groupCount()

参数：此方法不带任何参数。

返回值：此方法返回此匹配器模式中的捕获组数。

下面的示例说明了 Matcher.groupCount() 方法：

示例 1：

// Java code to illustrate groupCount() method
  
import java.util.regex.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Get the regex to be checked
        String regex = "Geeks";
  
        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);
  
        // Get the String to be matched
        String stringToBeMatched
            = "GeeksForGeeks";
  
        // Create a matcher for the input String
        Matcher matcher
            = pattern
                  .matcher(stringToBeMatched);
  
        // Get the number of capturing groups
        // using groupCount() method
        System.out.println(matcher.groupCount());
    }
}

输出：

0

示例 2：

// Java code to illustrate groupCount() method
  
import java.util.regex.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Get the regex to be checked
        String regex = "GFG";
  
        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);
  
        // Get the String to be matched
        String stringToBeMatched
            = "GFGFGFGFGFGFGFGFGFG";
  
        // Create a matcher for the input String
        Matcher matcher
            = pattern
                  .matcher(stringToBeMatched);
  
        // Get the number of capturing groups
        // using groupCount() method
        System.out.println(matcher.groupCount());
    }
}

输出：

0

参考： Oracle 文档