Java Matcher group(int)用法及代码示例

Matcher类的group(int group)方法用于从指定的组获取已经完成的匹配结果的组索引。

用法:

public String group(int group)

参数：该方法采用参数组，该参数组是需要从中匹配模式的组索引的组。

返回值：此方法返回与指定组匹配的第一个字符的索引。

异常：该方法抛出：

IllegalStateException如果尚未尝试匹配，或者先前的匹配操作失败。
IndexOutOfBoundsException如果模式中没有具有给定索引的捕获组。

下面的示例说明Matcher.group()方法：

范例1：

// Java code to illustrate group() method 
  
import java.util.regex.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Get the regex to be checked 
        String regex = "(G*s)"; 
  
        // 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 current matcher state 
        MatchResult result 
            = matcher.toMatchResult(); 
        System.out.println("Current Matcher:"
                           + result); 
  
        while (matcher.find()) { 
            // Get the group matched using group() method 
            System.out.println(matcher.group(1)); 
        } 
    } 
}

输出：

Current Matcher:java.util.regex.Matcher[pattern=(G*s) region=0,13 lastmatch=]
s
s

范例2：

// Java code to illustrate group() method 
  
import java.util.regex.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Get the regex to be checked 
        String regex = "(G*G)"; 
  
        // 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 current matcher state 
        MatchResult result 
            = matcher.toMatchResult(); 
        System.out.println("Current Matcher:"
                           + result); 
  
        while (matcher.find()) { 
            // Get the group matched using group() method 
            System.out.println(matcher.group(0)); 
        } 
    } 
}

输出：

Current Matcher:java.util.regex.Matcher[pattern=(G*G) region=0,19 lastmatch=]
G
G
G
G
G
G
G
G
G
G

参考： https://docs.oracle.com/javase/9/docs/api/java/util/regex/Matcher.html#group-int-

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注：本文由纯净天空筛选整理自Kirti_Mangal大神的英文原创作品 Matcher group(int) method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。