Convert integer into byte array (Java)

Have a look at the ByteBuffer class.

ByteBuffer b = ByteBuffer.allocate(4);//b.order(ByteOrder.BIG_ENDIAN); // optional, the initial order of a byte buffer is always BIG_ENDIAN.b.putInt(0xAABBCCDD);byte[] result = b.array();

Setting the byte order ensures that result[0] == 0xAA, result[1] == 0xBB, result[2] == 0xCC and result[3] == 0xDD.

Or alternatively, you could do it manually:

byte[] toBytes(int i){  byte[] result = new byte[4];  result[0] = (byte) (i >> 24);  result[1] = (byte) (i >> 16);  result[2] = (byte) (i >> 8);  result[3] = (byte) (i /*>> 0*/);  return result;}

The ByteBuffer class was designed for such dirty hands tasks though. In fact the private java.nio.Bits defines these helper methods that are used by ByteBuffer.putInt():

private static byte int3(int x) { return (byte)(x >> 24); }private static byte int2(int x) { return (byte)(x >> 16); }private static byte int1(int x) { return (byte)(x >>  8); }private static byte int0(int x) { return (byte)(x >>  0); }

Using BigInteger:

private byte[] bigIntToByteArray( final int i ) {    BigInteger bigInt = BigInteger.valueOf(i);          return bigInt.toByteArray();}

Using DataOutputStream:

private byte[] intToByteArray ( final int i ) throws IOException {          ByteArrayOutputStream bos = new ByteArrayOutputStream();    DataOutputStream dos = new DataOutputStream(bos);    dos.writeInt(i);    dos.flush();    return bos.toByteArray();}

Using ByteBuffer:

public byte[] intToBytes( final int i ) {    ByteBuffer bb = ByteBuffer.allocate(4);     bb.putInt(i);     return bb.array();}

use this function it works for me

public byte[] toByteArray(int value) {    return new byte[] {            (byte)(value >> 24),            (byte)(value >> 16),            (byte)(value >> 8),            (byte)value};}

it translates the int into a byte value