ByteBuffer allocateDirect() method in Java

A direct byte buffer can be allocated using the method allocateDirect() in the class java.nio.ByteBuffer. This method requires a single parameter i.e. the capacity in bytes and it returns the direct byte buffer. If the capacity provided is negative, then the IllegalArgumentException is thrown.

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.allocateDirect(n);
         byte[] byteValues = { 7, 1, 6, 3, 8 };
         buffer = ByteBuffer.wrap(byteValues);
         System.out.println("The direct ByteBuffer is: " + Arrays.toString(buffer.array()));
         System.out.println("\nThe state of the ByteBuffer is: ");
         System.out.println(buffer.toString());
      } catch (IllegalArgumentException e) {
         System.out.println("Error!!! IllegalArgumentException");
      } catch (ReadOnlyBufferException e) {
         System.out.println("Error!!! ReadOnlyBufferException");
      }
   }
}

Output

The direct ByteBuffer is: [7, 1, 6, 3, 8]
The state of the ByteBuffer is:
java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]