Java StringBuilder deleteCharAt() 方法

java StringBuilder deleteCharAt() 方法用于删除此序列中指定位置处的字符。此序列将缩短一个字符。

在 Java 中，索引指的是当前序列的字符位置。基本上，charAt() 方法用于检索指定索引处的字符。deleteCharAt() 方法接受一个整数参数，该参数保存字符索引的值。如果索引值为负或该值大于给定序列长度，则会抛出异常。

语法

以下是 Java StringBuilder deleteCharAt() 方法的语法：-

public StringBuilder deleteCharAt(int index)

参数

• index - 这是要删除的字符的索引。

返回值

此方法返回给定序列的子字符串。

示例：从 StringBuilder 中删除子字符串

如果索引值非负且小于序列长度，则此方法返回给定序列的新子字符串。

在以下示例中，我们使用值“Java lang package”创建了StringBuilder 类的对象。使用delete() 方法，我们尝试删除指定索引 3处的字符。

public class StringBuilderDemo {
   public static void main(String[] args) {
      //create an object of the StringBuilder
      StringBuilder sb = new StringBuilder("Java lang package");
      System.out.println("Before deletion the string is: " + sb);
      //initialize the index value
      int index = 3;
      System.out.println("The given index value is: " + index);
      //using the deleteCharAt() method
      System.out.println("After deletion the character at the specified index " + index + " index is: " + sb.deleteCharAt(index));
   }
}

输出

执行上述程序后，将产生以下结果：-

Before deletion the string is: Java lang package
The given index value is: 3
After deletion the character at the specified index 3 index is: Jav lang package

示例：在从 StringBuilder 中删除子字符串时遇到 StringIndexOutOfBoundsException

如果索引值大于给定序列长度，则此方法会抛出StringIndexOutOfBoundsException。

在此程序中，然后我们使用值“JavaProgramming”实例化StringBuilder 类。使用deleteCharAt() 方法，我们尝试删除指定索引 30处的字符，其值大于给定序列。

public class Delete {
   public static void main(String[] args) {
      try {
         //create an object of the StringBuilder
         StringBuilder sb = new StringBuilder("JavaProgramming");
         System.out.println("Before deletion the string is: " + sb);
         //initialize the index value
         int index = 30;// value is greater than the sequence length
         System.out.println("The given index value is: " + index);
         //using the deleteCharAt() method
         System.out.println("After deletion rhe remaing string is: " + sb.deleteCharAt(index));
      } catch(IndexOutOfBoundsException e) {
         e.printStackTrace();
         System.out.println("Exception: " + e);
      }
   }
}

输出

以下是上述程序的输出：-

Before deletion the string is: JavaProgramming
The given index value is: 30
java.lang.StringIndexOutOfBoundsException: Index 30 out of bounds for length 15
   at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:55)
   at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:52)
   at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:213)
   at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:210)
   at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:98)
   at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:106)
   at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:302)
   at java.base/java.lang.String.checkIndex(String.java:4557)
   at java.base/java.lang.AbstractStringBuilder.deleteCharAt(AbstractStringBuilder.java:957)
   at java.base/java.lang.StringBuilder.deleteCharAt(StringBuilder.java:486)
   at Delete.main(Delete.java:13)
Exception: java.lang.StringIndexOutOfBoundsException: Index 30 out of bounds for length 15

示例：在从 StringBuilder 中删除子字符串时遇到 StringIndexOutOfBoundsException

如果索引值包含负值，则在调用该方法时会抛出StringIndexOutOfBoundsException。

在以下示例中，我们创建了一个值为“TutorialsPoint”的StringBuilder。使用deleterCharAt() 方法，我们尝试删除指定索引 -1处的字符。

public class Demo {
   public static void main(String[] args) {
      try {
         //create an object of the StringBuilder
         StringBuilder sb = new StringBuilder("TutorialsPoint");
         System.out.println("Before deletion the string is: " + sb);
         //initialize the index value
         int index = -1;// holds the negative value
         System.out.println("The given index value is: " + index);
         //using the deleteCharAt() method
         System.out.println("After deletion rhe remaing string is: " + sb.deleteCharAt(index));
      } catch(IndexOutOfBoundsException e) {
         e.printStackTrace();
         System.out.println("Exception: " + e);
      }
   }
}

输出

上述程序产生以下结果：-

Before deletion the string is: TutorialsPoint
The given index value is: -1
java.lang.StringIndexOutOfBoundsException: Index -1 out of bounds for length 14
   at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:55)
   at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:52)
   at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:213)
   at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:210)
   at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:98)
   at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:106)
   at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:302)
   at java.base/java.lang.String.checkIndex(String.java:4557)
   at java.base/java.lang.AbstractStringBuilder.deleteCharAt(AbstractStringBuilder.java:957)
   at java.base/java.lang.StringBuilder.deleteCharAt(StringBuilder.java:486)
   at Demo.main(Demo.java:13)
Exception: java.lang.StringIndexOutOfBoundsException: Index -1 out of bounds for length 14