CharBuffer charAt() methods in Java with Examples

The charAt() method of java.nio.CharBuffer Class is used to read the character at the given index relative to the current position.

Syntax:

public final char charAt(int index)

Parameters: This method takes the index of the character to be read, relative to the position; must be non-negative and smaller than remaining().



Return Value: This method returns the character at index position() + index.

Exception: This method throws IndexOutOfBoundsException if the preconditions on index do not hold.

Below are the examples to illustrate the charAt(int index) method:

Example 1:

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// Java program to demonstrate
// charAt() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
        // Creating the CharBuffer
        try {
  
            // creating object of CharBuffer
            // and allocating size capacity
            CharBuffer charbuffer
                = CharBuffer.allocate(3);
  
            // append the value in CharBuffer
            // using append() method
            charbuffer.append('a')
                .append('b')
                .append('c')
                .rewind();
  
            // print the CharBuffer
            System.out.println("Original CharBuffer:  "
                               + Arrays.toString(
                                     charbuffer.array()));
  
            // Read char at particular Index
            // using charAt() method
            char value = charbuffer.charAt(2);
  
            // Display the value
            System.out.println("\nvalue at Index 0 is : "
                               + value);
        }
  
        catch (IndexOutOfBoundsException e) {
  
            System.out.println("\nindex is greater than"
                               + " the capacity minus 1");
            System.out.println("Exception throws : " + e);
        }
    }
}

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Output:

Original CharBuffer:  [a, b, c]

value at Index 0 is : c

Example 2: To demonstrate IndexOutOfBoundsException.

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// Java program to demonstrate
// charAt() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
        // Creating the CharBuffer
        try {
  
            // creating object of CharBuffer
            // and allocating size capacity
            CharBuffer charbuffer
                = CharBuffer.allocate(3);
  
            // append the value in CharBuffer
            // using append() method
            charbuffer.append('a')
                .append('b')
                .append('c')
                .rewind();
  
            // print the CharBuffer
            System.out.println("Original CharBuffer:  "
                               + Arrays.toString(
                                     charbuffer.array()));
  
            // Read char at particular Index
            // using charAt() method
            char value = charbuffer.charAt(3);
  
            // Display the value
            System.out.println("\nvalue at Index 0 is : "
                               + value);
        }
  
        catch (IndexOutOfBoundsException e) {
  
            System.out.println("\nindex is greater than"
                               + " the capacity minus 1");
            System.out.println("Exception throws : " + e);
        }
    }
}

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Output:

Original CharBuffer:  [a, b, c]

index is greater than the capacity minus 1
Exception throws : java.lang.IndexOutOfBoundsException

Reference: https://docs.oracle.com/javase/9/docs/api/java/nio/CharBuffer.html#charAt-int-



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