Java StringBuilder deleteCharAt()方法及实例

StringBuilder类 的 deleteCharAt(int index) 方法从StringBuilder包含的字符串中删除给定索引处的字符。该方法将index作为参数，代表我们要删除的字符的索引，并将剩余的字符串作为StringBuilder对象返回。使用该方法后，这个StringBuilder缩短了一个字符。 语法

public StringBuilder deleteCharAt(int index)

参数： 该方法接受一个参数 index ，代表你要删除的字符的索引。
返回值： 该方法在删除字符后返回 这个StringBuilder对象 。
异常： 如果索引小于0，或者索引大于String的长度，该方法会抛出 StringIndexOutOfBoundsException 。下面的程序演示了StringBuilder类的deleteCharAt()方法：

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

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

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

**参考资料: ** https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuilder.html#deleteCharAt(int)