ByteBuffer asReadOnlyBuffer() method in Java

A read-only byte buffer can be created using the contents of a buffer with the method asReadOnlyBuffer() in the class java.nio.ByteBuffer. The new buffer cannot have any modifications as it is a read-only buffer. However, the capacity, positions, limits etc. of the new buffer are the same as the previous buffer.

A program that demonstrates this is given as follows −

Example

 Live Demo

import java.nio.*;
import java.util.*;
public class Demo {
   public static void main(String[] args) {
      int n = 5;
      try {
         ByteBuffer buffer = ByteBuffer.allocate(5);
         buffer.put((byte) 1);
         buffer.put((byte) 2);
         buffer.put((byte) 3);
         buffer.put((byte) 4);
         buffer.put((byte) 5);
         buffer.rewind();
         System.out.println("The Original ByteBuffer is: " + Arrays.toString(buffer.array()));
         ByteBuffer roBuffer = buffer.asReadOnlyBuffer();
         System.out.println("The ReadOnlyBuffer ByteBuffer is: ");
         while (roBuffer.hasRemaining())
            System.out.print(roBuffer.get() + " ");
      } catch (IllegalArgumentException e) {
         System.out.println("Error!!! IllegalArgumentException");
      } catch (ReadOnlyBufferException e) {
         System.out.println("Error!!! ReadOnlyBufferException");
      }
   }
}

Output

The Original ByteBuffer is: [1, 2, 3, 4, 5]
The ReadOnlyBuffer ByteBuffer is:
1 2 3 4 5