New to Java

Need help with some code, It is supposed to add two integers using only recursion, cannot use any operators such as (+,-,/,*,%) can use -- and ++, i got it working for multiplying positive numbers but it only works with negatives sometimes, when sending in

4,4 = 16 Check
-4,4 = -16 Check
4,-4 = 16 Wrong
-4,-4 = -16 Wrong

I can't seem to figure out a way to make it work in all cases.

   import javax.swing.*;
   import java.lang.*;
  
	
    public class Recursion{
   
       public static void main(String[] args)
      {
         initialize();
         gatherAndCall();
      
      }
      private static int tot = 0;
      private static int divide = 0;
      private static int count = -1;
   
   
       public static void initialize()
      {
         int tot = 0;
         int divide = 0;
         int count = -1;
      
      }
   	
       public static void choose()
      {
         String[] choose = {"continue","exit"};
         String options = (String) JOptionPane.showInputDialog(null, "Please select an option below...",
            "Toggle Display", JOptionPane.QUESTION_MESSAGE, null,                                                          // icon
            choose, // Array of choices
            choose[0]); // Initial choice
      		
         if(options.equals("continue"))
         {
            initialize();
            tot = 0;
            gatherAndCall();
         }
      
         if(options.equals("exit"))
            System.exit(0);	
      
      }
   
       public static void gatherAndCall()
      {
         String[] choose = {"add","subtract","multiply","divide","mod","all"};
         String options = (String) JOptionPane.showInputDialog(null, "Please select an option below...",
            "Toggle Display", JOptionPane.QUESTION_MESSAGE, null,                                                          // icon
            choose, // Array of choices
            choose[5]); // Initial choice
      		
      		
         String numbers =JOptionPane.showInputDialog("Please Enter Two Number Seperated By A Comma: ");
         int loc = numbers.indexOf(',');
         String sub1 = numbers.substring(0,loc);
         String sub2 = numbers.substring(loc+1);
         int a = Integer.parseInt(sub1);
         int b = Integer.parseInt(sub2);		
      
         if(options.equals("add"))
            System.out.println(a+" Plus "+b+" = " +Recursion.add(a,b));
         if(options.equals("subtract"))
            System.out.println(a+" Minus "+b+" = " + Recursion.subtract(a,b));
         if(options.equals("multiply"))
            System.out.println(a+" Times "+b+" = " + Recursion.multiply(a,b));
         if(options.equals("divide"))
            if(Recursion.divide(a,b)==12321)
               System.out.println("You divided by Zero");
            else{	
               System.out.println(a+" Divided "+b+" = " +Recursion.divide(a,b));
            }
         if(options.equals("mod"))
            System.out.println(a+" Mod "+b+" = " +Recursion.mod(a,b));	
         if(options.equals("all"))
         {		
            System.out.println(a+" Plus "+b+" = " +Recursion.add(a,b));	
            System.out.println(a+" Minus "+b+" = " +Recursion.subtract(a,b));	
            System.out.println(a+" Times "+b+" = " +Recursion.multiply(a,b));	
            System.out.println(a+" Divided "+b+" = " +Recursion.divide(a,b));
            System.out.println(a+" Mod "+b+" = " +Recursion.mod(a,b));
         }
      	
         choose();
      
      }
       public static int add(int a, int b)
      {
         if(a <= 0)
            return (a < 0) ? add(MCH.succ(a), MCH.pred(b)) : b;
         else
            return (a > 0) ? add(MCH.pred(a), MCH.succ(b)) : b;
      	
      }
   
       public static int subtract(int a, int b)
      {
         if(b <= 0)
            return (b < 0) ? subtract(MCH.succ(a), MCH.succ(b)) : a;
         else
            return (b > 0) ? subtract(MCH.pred(a), MCH.pred(b)) : a;
      }
   	
       public static int multiply(int a, int b)
      {
      
         if (b==0) 
            return(tot);
         else
         {	 
            tot = add(tot,a);
         	
            if(b<0)
               b=MCH.succ(b);
            
            else
               b=MCH.pred(b);
           
            multiply(a,b);
         }
         return (tot);
      	
      }
   	
   }

Thanks for any help also if any part of the code looks really inefficient and you know a better method please let me know thanks.