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 Articles > Java > Basics > How to convert Double to Byte Array

How to convert Double to Byte Array 

The following example shows converting a Double to Byte array. Since a Java Double occupies 8 bytes allocate a ByteBuffer of capacity 8 and write the Double to ByteBuffer. It updates the ByteBuffer with 8 bytes representing the Double. Finally convert the ByteBuffer to byte array.

java.nio.ByteBuffer
  • public static ByteBuffer allocate(int capacity)
    Allocates a new byte buffer of given capacity.
  • public ByteBuffer putDouble(double value)
    Writes eight bytes containing the given double value to this ByteBuffer.
  • public final byte[] array()
    Returns the ByteBuffer as byte array.

File Name  :  
com/bethecoder/articles/basics/prim2bytea/Double2ByteArrayTest.java 
Author  :  Sudhakar KV
Email  :  [email protected]
   
package com.bethecoder.articles.basics.prim2bytea;

import java.nio.ByteBuffer;
import java.util.Arrays;

public class Double2ByteArrayTest {

  /**
   * @param args
   */
  public static void main(String[] args) {
    //Since double occupies 8 bytes allocate a buffer of size 8
    byte [] bytes = ByteBuffer.allocate(8).putDouble(1729.1729).array();
    System.out.println(Arrays.toString(bytes));
  }

}
   

It gives the following output, 
[64, -101, 4, -79, 12, -78, -107, -22]



 
  


  
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