converting bytes to int in Java

Question

I need to convert 2 bytes (2's complement) into an int in Java code. how do I do it?

toInt(byte hb, byte lb)
{

}

Answer 1

return ((int)hb << 8) | ((int)lb & 0xFF);

Correct operation in all cases is left as an exercise for the student.

Answer 2

public int toInt(byte hb, byte lb)
{
    return ((int)hb)<<8 + lb;
}

Answer 3

You can also use the ByteBuffer class:

public int toInt(byte hb, byte lb) {
    ByteBuffer bb = ByteBuffer.wrap(new byte[] {hb, lb});
    return bb.getShort(); // Implicitly widened to an int per JVM spec.
}

This class might be helpful if you're decoding a lot of data.