2 bytes to short java

Question

i\'m reading 133 length packet from serialport,last 2 bytes contain CRC values,2 bytes value i\'ve make single(short i think) using java. this what i have done,

Answer 1

This happens when trying to concatenate bytes (very subtle)

byte b1 = (byte) 0xAD;
byte b2 = (byte) 0xCA;
short s = (short) (b1<<8 | b2);

The above produces 0xFFCA, which is wrong. This is because b2 is negative (byte type is signed!), which means that when it will get converted to int type for the bit-wise | operation, it will be left-padded with 0xF!

Therefore, you must remember to mask-out the padded bytes so that they will definitely be zero:

short s = (short) (b1<<8 | b2 & 0xFF);