Java – when we change to bytes, why is the result – 2 when 127 * 2?

This is my code:

public class test {

  public static void main(String[] args) {
    byte a=(byte)127,b=2;    
    byte c=(byte)(a*b);

    System.out.println(c);
  }    
}

Why is the result - 2?

Solution

Because a * B will result in a temporary int variable, i.e. 254, i.e. 1111 1110 When converted to byte, this is treated as a signed value MSB is 1, so its value is negative, and the value is – ((INV) 111 1110) 1) = – ((000 0001) 1) = - 2