Java Java.lang.String.startswith()用法及代碼示例

startswith()方法有兩種變體。本文介紹了所有這些變體，如下所示：1.字符串startsWith()：此方法測試字符串是否從第一個索引開始以指定的前綴開頭。

Syntax
public boolean startsWith(String prefix)
參數
prefix: the prefix to be matched.
Return Value
It returns true if the character sequence 
represented by the argument is a prefix of the character 
sequence represented by this string; false otherwise.

// Java code to demonstrate the 
// working of  startsWith() 
public class Strt1 { 
public static void main(String args[]) 
    { 
  
        // Initialising String 
        String Str = new String("Welcome to geeksforgeeks"); 
  
        // Testing the prefix using startsWith() 
        System.out.print("Check whether string starts with Welcome:"); 
        System.out.println(Str.startsWith("Welcome")); 
  
        // Testing the prefix using startsWith() 
        System.out.print("Check whether string starts with geeks:"); 
        System.out.println(Str.startsWith("geeks")); 
    } 
}

輸出：

Check whether string starts with Welcome:true
Check whether string starts with geeks:false

2.字符串startsWith(String prefix，int strt_pos)：此變體具有兩個參數，並測試字符串是否以指定的前綴開頭並以指定的索引開頭。

Syntax
public boolean startsWith(String prefix, int strt_pos)
參數
prefix:the prefix to be matched.
strt_pos: where to begin looking in the string.
Return Value
It returns true if the character sequence
represented by the argument is a prefix of the character
sequence represented by this string; false otherwise.

// Java code to demonstrate the 
// working of  startsWith() 
public class Strt2 { 
public static void main(String args[]) 
    { 
  
        // Initialising String 
        String Str = new String("Welcome to geeksforgeeks"); 
  
        // Testing the prefix using startsWith() 
        System.out.print("Check whether string starts with Welcome at pos 11:"); 
        System.out.println(Str.startsWith("Welcome", 11)); 
  
        // Testing the prefix using startsWith() 
        System.out.print("Check whether string starts with geeks at pos 11:"); 
        System.out.println(Str.startsWith("geeks", 11)); 
    } 
}

輸出：

Check whether string starts with Welcome at pos 11:false
Check whether string starts with geeks at pos 11:true

可能的應用：此方法主要可用於過濾前綴，例如。過濾以數字開頭的電話號碼或以特定字母開頭的姓名。本文對此進行了解釋。

// Java code to demonstrate the 
// application of  startsWith() 
public class Appli { 
public static void main(String args[]) 
    { 
  
        // Initialising String 
        String Str = new String("Astha Tyagi"); 
  
        // Testing the prefix using startsWith() 
        System.out.print("Check whether Astha Tyagi starts with A:"); 
        System.out.println(Str.startsWith("A")); 
    } 
}

輸出：

Check whether Astha Tyagi starts with A:true

相關用法

注：本文由純淨天空篩選整理自 Java.lang.String.startswith() in Java。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。