Byte Array and Int conversion in Java

Your methods should be (something like)

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

public static byte[] intToByteArray(int a)
{
    return new byte[] {
        (byte) ((a >> 24) & 0xFF),
        (byte) ((a >> 16) & 0xFF),   
        (byte) ((a >> 8) & 0xFF),   
        (byte) (a & 0xFF)
    };
}

These methods were tested with the following code :

Random rand = new Random(System.currentTimeMillis());
byte[] b;
int a, v;
for (int i=0; i<10000000; i++) {
    a = rand.nextInt();
    b = intToByteArray(a);
    v = byteArrayToInt(b);
    if (a != v) {
        System.out.println("ERR! " + a + " != " + Arrays.toString(b) + " != " + v);
    }
}
System.out.println("Done!");