How to convert int[] to byte[]

Question

I have an array of integers which represent a RGB image and would like to convert it to a byte array and save it to a file.

What's the best way to convert an array of integers to the array of bytes in Java?

Answer 1

As Brian says, you need to work out how what sort of conversion you need.

Do you want to save it as a "normal" image file (jpg, png etc)?

If so, you should probably use the Java Image I/O API.

If you want to save it in a "raw" format, the order in which to write the bytes must be specified, and then use an IntBuffer and NIO.

As an example of using a ByteBuffer/IntBuffer combination:

import java.nio.*; import java.net.*;  class Test {        public static void main(String [] args)         throws Exception // Just for simplicity!     {         int[] data = { 100, 200, 300, 400 };          ByteBuffer byteBuffer = ByteBuffer.allocate(data.length * 4);                 IntBuffer intBuffer = byteBuffer.asIntBuffer();         intBuffer.put(data);          byte[] array = byteBuffer.array();          for (int i=0; i < array.length; i++)         {             System.out.println(i + ": " + array[i]);         }     } } 

Answer 2

Maybe use this method

byte[] integersToBytes(int[] values) {    ByteArrayOutputStream baos = new ByteArrayOutputStream();    DataOutputStream dos = new DataOutputStream(baos);    for(int i=0; i < values.length; ++i)    {         dos.writeInt(values[i]);    }     return baos.toByteArray(); }