Perform binary addition and subtraction with a signed binary numbers in Java -

for pure enjoyment , on time, i'm trying learn more binary numbers , assembly. have been local library checking out books in order gain more understanding of binary numbers , addition. didn't know before few weeks back, 1 add binary numbers java. i'm stumbled , have been 2 days on this.

like said i'm trying add binary numbers in addition , subtraction. i'm assuming need parse in order work properly. feel i'm on looking here. missing? helpful.

as of right now, have this:

`import java.util.scanner; public class binary operation { public static void main(string[]args){     scanner keyboard = new scanner(system.in);     boolean keepgoing = true;     string binary1, binary2;     int num1, num2;      system.out.println("scenario: choose (a)dd, (s)ubtract, (e)xit");     char choice = keyboard.next().charat(0);     while(keepgoing){         if (choice == 'a' || choice == 'a'){             system.out.println("enter 8-bit signed binary number: ");              binary1 = keyboard.next();             system.out.println("enter binary number: ");             binary2 = keyboard.next();             num1 = integer.parseint(binary1, 2);             num2 = integer.parseint(binary2, 2);             int sum = num1 + num2;             system.out.println(integer.tobinarystring(sum));         }         else if(choice == 's' || choice == 's'){             system.out.println("enter 8-bit signed binary number: ");             binary1 = keyboard.next();             system.out.println("enter binary number: ");             binary2 = keyboard.next();             num1 = integer.parseint(binary1, 4);             num2 = integer.parseint(binary2, 4);             int difference = num1 - num2;             system.out.println(integer.tobinarystring(difference));         }         else if(choice == 'e' || choice == 'e'){             system.out.println("thank you.");             keepgoing = false;             system.exit(0);         }         if(keepgoing){             system.out.println("choose (a)dd, (s)ubtract, (e)xit");             choice = keyboard.next().charat(0);         }     } 

the tobinarystring prints 32-bit unsigned value. need method like.

public static string tosignedbinary(int num) {     return num < 0 ? "-" + long.tobinarystring(-(long) num) : integer.tobinarystring(num); }