Bitwise negation gives unexpected result

Question

I am trying to write a bitwise calculator in java, something that you could input an expression such as ~101 and it would give back 10 however when i run this code

Answer 1

101 in integer is actually represented as 00000000000000000000000000000101 negate this and you get 11111111111111111111111111111010 - this is -6.