NIO: wrap existing array into a buffer

ByteBuffer class provides ‘wrap’ method, it wraps a byte array into a buffer.

public static ByteBuffer wrap(byte[] array)

public static ByteBuffer wrap(byte[] array, int offset, int length)

Above methods wraps the byte array into a byte buffer. The new buffer will be backed by the given byte array. That is Modifications to the array will cause buffer to be modified and vice versa. 

Find the below working application.

Test.java

package com.sample.app;

import java.io.IOException;
import java.nio.ByteBuffer;

public class Test {

 private static void printMetaInfo(String message, ByteBuffer byteBuffer) {
  System.out.println(message);
  System.out.printf("Limit : %d\n", byteBuffer.limit());
  System.out.printf("Capacity : %d\n", byteBuffer.capacity());
  System.out.printf("Position : %d\n", byteBuffer.position());
 }

 private static void printBuffer(String message, ByteBuffer byteBuffer) {
  System.out.println(message);
  for (int i = 0; i < byteBuffer.capacity(); i++) {
   System.out.println(byteBuffer.get(i));
  }
 }

 public static void main(String... args) throws IOException {
  byte[] arr = { 64, 65, 66, 67, 68 };
  ByteBuffer byteBuffer = ByteBuffer.wrap(arr);

  printMetaInfo("Meta information of byteBuffer", byteBuffer);
  printBuffer("\nElements of the byte buffer are", byteBuffer);

 }
}

Output

Meta information of byteBuffer

Limit : 5

Capacity : 5

Position : 0

Elements of the byte buffer are

64

65

66

67

68

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