Java Matcher start()用法及代碼示例

Matcher類的start()方法用於獲取已經完成的匹配結果的起始索引。

用法:

public int start()

參數：此方法不帶任何參數。

返回值：此方法返回匹配的第一個字符的索引。0

異常：如果尚未嘗試匹配，或者先前的匹配操作失敗，則此方法引發IllegalStateException。

下麵的示例說明Matcher.start()方法：

示例1:

// Java code to illustrate start() method 
  
import java.util.regex.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // Get the regex to be checked 
        String regex = "(G*k)"; 
  
        // Create a pattern from regex 
        Pattern pattern 
            = Pattern.compile(regex); 
  
        // Get the String to be matched 
        String stringToBeMatched = "Geeks"; 
  
        // 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 first index of match result 
            System.out.println(matcher.start()); 
        } 
    } 
}

輸出：

Current Matcher: java.util.regex.Matcher[pattern=(G*k) region=0,5 lastmatch=]
3

示例2:

// Java code to illustrate start() 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 = "GFG"; 
  
        // 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 first index of match result 
            System.out.println(matcher.start()); 
        } 
    } 
}

輸出：

Current Matcher: java.util.regex.Matcher[pattern=(G*G) region=0,3 lastmatch=]
0
2

參考： Oracle Doc

相關用法

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 start() 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。