Convert byte value from signed to unsigned
Use '&' operation with 0xFF as follows.
Suppose signed byte value is byt (-120,64,....).
byt & 0xFF
Above will convert signed to unsigned and return unsigned value.
Convert byte value from unsigned to signed
ByteBuffer byteBuff = ByteBuffer.allocate(4);
by[i] = byteBuff.get(3);
Above code convert unsigned values to sign byte values.