Java Programming

Hi my assignment is to convert the users input from binary to decimal or decimal to binary depending on the users input. If the user inputs a binary string my program should return decimal equivalents, whether the input is signed magnitude, one's complement, or two's complement. So far my program only works for unsigned input.

So the question is what should I do to have the program return equivalents if the user enters a binary string in signed magnitude format, one's complent, or two's complement?

import java.util.*;
public class programming1
{
    public static void main(String[]args)
    {
        String x;
        
        Scanner keyboard = new Scanner(System.in);
        
        System.out.println("Enter one of two types of input: \n"
                           + "An 8-bit string or a decimal "
                           + "integer (-128, + 127): ");
        x = keyboard.next();
        
        if (x.length() == 8)
        {
            System.out.println("The decimal equivalent of " + x
                               + " is " + Integer.parseInt(x, 2));
        }
        else
        {
            byte y = (byte)Integer.parseInt(x);
            System.out.println("The binary equivalent of " + x
                               + " is " + Integer.toBinaryString(y));
        }
      
    }

}