Question

I am calculating 16 bit checksum on my data which i need to send to server where it has to recalculate and match with the provided checksum. Checksum value that i am getting is in int but i have only 2 bytes for sending the value.So i am casting int to short while calling shortToBytes method. This works fine till checksum value is less than 32767 thereafter i am getting negative values.

Thing is java does not have unsigned primitives, so i am not able to send values greater than max value of signed short allowed.

How can i do this, converting int to short and send over the network without worrying about truncation and signed & unsigned int.

Also on both the side i have java program running.

   private byte[] shortToBytes(short sh) {
        byte[] baValue = new byte[2];
        ByteBuffer buf = ByteBuffer.wrap(baValue);
        return buf.putShort(sh).array();
    }

    private short bytesToShort(byte[] buf, int offset) {
        byte[] baValue = new byte[2];
        System.arraycopy(buf, offset, baValue, 0, 2);
        return ByteBuffer.wrap(baValue).getShort();
    }

Answer 1

You are still getting the same bit value as the server. So, to see the right numerical value replace the ByteBuffer.wrap(baValue).getShort() to a ByteBuffer.wrap(baValue).getInt(). This should give you the same numerical value as the server.