Java中的 StringBuilder deleteCharAt() 示例

StringBuilder 类的deleteCharAt(int index)方法从 StringBuilder 包含的 String 中删除给定索引处的字符。该方法将 index 作为参数，表示我们要删除的 char 的索引，并将剩余的 String 作为 StringBuilder 对象返回。应用此方法后，此 StringBuilder 会缩短一个字符。

句法：

public StringBuilder deleteCharAt(int index)

参数：此方法接受一个参数index表示要删除的字符的索引。

返回值：此方法在删除字符后返回此 StringBuilder 对象。

异常：如果索引小于零或索引大于字符串的长度，此方法将抛出StringIndexOutOfBoundsException 。

下面的程序演示了 StringBuilder 类的 deleteCharAt() 方法：

示例 1：

// Java program to demonstrate
// the deleteCharAt() 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("Before removal String = "
                           + str.toString());
  
        // remove the Character from index 8
        StringBuilder afterRemoval = str.deleteCharAt(8);
  
        // print string after removal of Character
        System.out.println("After removal of character"
                           + " at index 8 = "
                           + afterRemoval.toString());
    }
}

输出：

Before removal String = WelcomeGeeks
After removal of character at index 8 = WelcomeGeks

示例 2：

// Java program to demonstrate
// the deleteCharAt() Method.
  
class GFG {
    public static void main(String[] args)
    {
  
        // create a StringBuilder object
        // with a String pass as parameter
        StringBuilder
            str
            = new StringBuilder("GeeksforGeeks");
  
        // print string
        System.out.println("Before removal String = "
                           + str.toString());
  
        // remove the Character from index 3
        str = str.deleteCharAt(3);
  
        // print string after removal of Character
        System.out.println("After removal of Character"
                           + " from index=3"
                           + " String becomes => "
                           + str.toString());
  
        // remove the substring from index 5
        str = str.deleteCharAt(5);
  
        // print string after removal of Character
        System.out.println("After removal of Character"
                           + " from index=5"
                           + " String becomes => "
                           + str.toString());
    }
}

输出：

Before removal String = GeeksforGeeks
After removal of Character from index=3 String becomes => GeesforGeeks
After removal of Character from index=5 String becomes => GeesfrGeeks

示例 3：演示 IndexOutOfBoundException

// Java program to demonstrate
// exception thrown by the deleteCharAt() Method.
  
class GFG {
    public static void main(String[] args)
    {
  
        // create a StringBuilder object
        // with a String pass as parameter
        StringBuilder
            str
            = new StringBuilder("evil dead_01");
  
        try {
  
            // make index > length of String
            StringBuilder
                afterRemoval
                = str.deleteCharAt(14);
        }
  
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出：

Exception: java.lang.StringIndexOutOfBoundsException: String index out of range: 14

参考：
https://docs.oracle.com/javase/10/docs/api/java Java)