Java Matcher group(int)用法及代碼示例

Matcher類的group(int group)方法用於從指定的組獲取已經完成的匹配結果的組索引。

用法:

public String group(int group)

參數：該方法采用參數組，該參數組是需要從中匹配模式的組索引的組。

返回值：此方法返回與指定組匹配的第一個字符的索引。

異常：該方法拋出：

IllegalStateException如果尚未嘗試匹配，或者先前的匹配操作失敗。
IndexOutOfBoundsException如果模式中沒有具有給定索引的捕獲組。

下麵的示例說明Matcher.group()方法：

範例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)); 
        } 
    } 
}

輸出：

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

範例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)); 
        } 
    } 
}

輸出：

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

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

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注：本文由純淨天空篩選整理自Kirti_Mangal大神的英文原創作品 Matcher group(int) method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。