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Convert an int to a byte array (See related posts)

    public static byte[] intToByteArray(int value) {
        byte[] b = new byte[4];
        for (int i = 0; i < 4; i++) {
            int offset = (b.length - 1 - i) * 8;
            b[i] = (byte) ((value >>> offset) & 0xFF);
        }
        return b;
    }
to java by aeden on Sat Apr 09 00:56:01 -0400 2005

Comments on this post

toxi posts on Sep 12, 2006 at 19:14
a much faster (60%) version would be that:

public static final byte[] intToByteArray(int value) {
return new byte[]{
(byte)(value >>> 24), (byte)(value >> 16 & 0xff), (byte)(value >> 8 & 0xff), (byte)(value & 0xff) };
}
MichaelTague posts on Nov 15, 2007 at 18:12
The masks aren't necessary. The byte casts do the job:

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


The inverse of this, byte array to int, would be:

public static final int byteArrayToInt(byte [] b) {
        return (b[0] << 24)
                + ((b[1] & 0xFF) << 16)
                + ((b[2] & 0xFF) << 8)
                + (b[3] & 0xFF);
}

The masks are needed here because when the byte is widened to an int sign extension may add lots of bits that we get ride of with the mask.

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