Java StringBuilder replace()方法及示例

StringBuilder类的 replace(int start, int end, String str) 方法用于用指定的String中的字符替换这个序列的子串中的字符。子串从指定的索引start开始，延伸到索引end-1的字符，如果没有这样的字符，则延伸到序列的末端。首先，子串中的字符被删除，然后插入作为参数传递的字符串，以代替这些字符。

语法

public StringBuilder replace?(int start, int end, String str)

参数：

这个方法接受三个参数。

start – 整数类型的值，指的是起始索引。
end – 整数类型的值，指的是结束索引。
str - 字符串类型的值，指的是将替换之前内容的字符串。

返回：

该方法在成功替换字符后返回StringBuilder对象。

异常：

如果start是负数，大于length()，或者大于end，则出现StringIndexOutOfBoundsException。

下面的程序说明了java.lang.StringBuilder.replace()方法：

例1 :

// Java program to demonstrate
// the replace() Method.
  
class GFG {
    public static void main(String[] args)
    {
  
        // create a StringBuilder object
        // with a String pass as parameter
        StringBuilder str
            = new StringBuilder("WelcomeGeeks");
  
        // print string
        System.out.println("String = "
                           + str.toString());
  
        // replace Character from index 1 to 7 by "e are "
        StringBuilder strReturn = str.replace(1, 7, "e are ");
  
        // print string
        System.out.println("After Replace() String = "
                           + strReturn.toString());
    }
}

输出

String = WelcomeGeeks
After Replace() String = We are Geeks

例2 :

// Java program to demonstrate
// the replace() Method.
  
class GFG {
    public static void main(String[] args)
    {
  
        // create a StringBuilder object
        // with a String pass as parameter
        StringBuilder str
            = new StringBuilder("Tony Stark will die");
  
        // print string
        System.out.println("String = "
                           + str.toString());
  
        // replace Character from index 15 to 16 by " not "
        StringBuilder strReturn = str.replace(15, 16, " not ");
  
        // print string
        System.out.println("After Replace() String = "
                           + strReturn.toString());
    }
}

输出

String = Tony Stark will die
After Replace() String = Tony Stark will not die

例3： 当传递负的指数时。

// Java program to demonstrate
// Exception thrown by the replace() Method.
  
class GFG {
    public static void main(String[] args)
    {
  
        // create a StringBuilder object
        // with a String pass as parameter
        StringBuilder str
            = new StringBuilder("Tony Stark");
  
        try {
            // replace Character from index -15 to 16 by "Captain America"
            StringBuilder strReturn = str.replace(-15, 16, "Captain America");
        }
        catch (Exception e) {
  
            e.printStackTrace();
        }
    }
}

输出

java.lang.StringIndexOutOfBoundsException: String index out of range: -15
    at java.lang.AbstractStringBuilder.replace(AbstractStringBuilder.java:851)
    at java.lang.StringBuilder.replace(StringBuilder.java:262)
    at GFG.main(File.java:17)

例4： 当传递的起始索引大于结束索引时。

// Java program to demonstrate
// Exception thrown by the replace() Method.
  
class GFG {
    public static void main(String[] args)
    {
  
        // create a StringBuilder object
        // with a String pass as parameter
        StringBuilder str
            = new StringBuilder("Tony Stark");
  
        try {
            // replace Character from index 5 to 3 by "Captain America"
            StringBuilder strReturn = str.replace(5, 3, "Captain America");
        }
        catch (Exception e) {
  
            e.printStackTrace();
        }
    }
}

输出

java.lang.StringIndexOutOfBoundsException: start > end
    at java.lang.AbstractStringBuilder.replace(AbstractStringBuilder.java:855)
    at java.lang.StringBuilder.replace(StringBuilder.java:262)
    at GFG.main(File.java:17)