Java byte value not correct

Question

I have this hex value 93 which in decimal value should be 147. Since this number is less than 255, it is representable in a byte.

In java I did this

System.out.println((new Integer(1)).byteValue()); //prints 1
System.out.println((new Integer(147)).byteValue()); //prints -109!!! WHY?

What am I not understanding? with integer of 147 instead of printing 147 it prints -109...

Answer 1

A byte in Java is signed , therefore it represents the values in the range of -128 to 127, as opposed to the unsigned alternative in other languages in the range of 0 to 255. All of Java's integer types are signed, excluding char since since it's used to hold 16-bit Unicode values from 0 to 65535.

The value 147 stored as a byte is represented in binary as:

10010011

Since according to the Oracle docs a byte is: "an 8-bit signed two's complement integer" , the signed value becomes:

= -2^7 + 2^4 + 2^1 + 2^0
= -128 + 16 + 2 + 1
= -109

Answer 2

Because byte is in the range -128:127 ( see here ). When you call byteValue() you can't get anything out of that range, so it overflows (and starts from the lowest value)