Java Java.lang.String.startswith()用法及代码示例

startswith()方法有两种变体。本文介绍了所有这些变体，如下所示：1.字符串startsWith()：此方法测试字符串是否从第一个索引开始以指定的前缀开头。

Syntax
public boolean startsWith(String prefix)
参数
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")); 
    } 
}

输出：

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

2.字符串startsWith(String prefix，int strt_pos)：此变体具有两个参数，并测试字符串是否以指定的前缀开头并以指定的索引开头。

Syntax
public boolean startsWith(String prefix, int strt_pos)
参数
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)); 
    } 
}

输出：

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

可能的应用：此方法主要可用于过滤前缀，例如。过滤以数字开头的电话号码或以特定字母开头的姓名。本文对此进行了解释。

// 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")); 
    } 
}

输出：

Check whether Astha Tyagi starts with A:true

相关用法

注：本文由纯净天空筛选整理自 Java.lang.String.startswith() in Java。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。