How can I create a calculator that save result in memory and recall it back

Question

I need some advice or help on how i can save the result and call it back by typing 'm' for memory, 'r' for recalling the saved result, and 'c' to set the result back to zero.
i have tried many ways but it doesn't seem to save the result.
Here is the code of what i have so far.
so, please if anyone could help me , it would be greatly appriciated.
import java.util.Scanner;
public class ImpCalculator
     private double result;
     private double memory;
     private double precision = 0.0001;
     public static void main (String [] args)
          Calculator clerk = new Calculator ();
          try
               System.out.println ("Calculator is on.");
               System.out.print ("Format of each line: ");
               System.out.println ("operator space number");
               System.out.println ("For example: + 3");
               System.out.println ("To save result, enter the letter m.");
               System.out.println ("To recall result, enter the letter r.");
               System.out.println ("To clear result, enter the letter c.");
               System.out.println ("To end, enter the letter e.");
               clerk.doCalculation ();
          catch (UnknownOpException e)
               clerk.handleUnknownOpException (e);
          catch (DivideByZeroException e)
               clerk.handleDivideByZeroException (e);
          System.out.println ("The final result is " + clerk.getResult ());
          System.out.println ("Calculator program ending.");               
     public ImpCalculator ()
          result = 0;
          memory = 0;
     public void handleDivideByZeroException (DivideByZeroException e)
          System.out.println ("Dividing by zero.");
          System.out.println ("Program aborted");
          System.exit (0);
     public void handleUnknownOpException (UnknownOpException e)
          System.out.println (e.getMessage ());
          System.out.println ("Try again from the beginning:");
          try
               System.out.print ("Format of each line: ");
               System.out.println ("operator number");
               System.out.println ("For example: + 3");
               System.out.println ("To end, enter the letter e.");
               doCalculation ();
          catch (UnknownOpException e2)
               System.out.println (e2.getMessage ());
               System.out.println ("Try again at some other time.");
               System.out.println ("Program ending.");
               System.exit (0);
          catch (DivideByZeroException e3)
               handleDivideByZeroException (e3);
     public void reset ()     
          result = 0;
     public void setResult (double newResult)
          result = newResult;
     public double getResult ()
          return result;
     public void setMemory (double newMemory)
          memory = newMemory;
     public double recall ()
          return memory;
     public double evaluate (char op, double n1, double n2)
          throws DivideByZeroException, UnknownOpException
          double answer;
          switch (op)
               case '+':
                    answer = n1 + n2;
                    break;
               case '-':
                    answer = n1 - n2;
                    break;
               case '*':
                    answer = n1 * n2;
                    break;
               case '/':
                    if ((-precision < n2) && (n2 < precision))                         
                         throw new DivideByZeroException     ();          
                    answer = n1 / n2;
                    break;
               default:
                    throw new UnknownOpException (op);
          return answer;     
     public void doCalculation () throws DivideByZeroException, UnknownOpException
          Scanner keyboard = new Scanner (System.in);
          boolean done = false;
          result = 0;
          System.out.println ("result = " + result);
          while (!done)
               char nextOp = (keyboard.next ()).charAt (0);
               if ((nextOp == 'e') || (nextOp == 'E'))
                    done = true;
               else if ((nextOp == 'c') || (nextOp == 'C'))
                    result = 0.0;     
               else if ((nextOp == 'm') || (nextOp == 'M'))
                    memory = result;
               else if ((nextOp == 'r') || (nextOp == 'R'))
                    System.out.println ("memory value = " + recall ());
               else
                    double nextNumber = keyboard.nextDouble ();
                    result = evaluate (nextOp, result, nextNumber);
                    System.out.println ("result " + nextOp + " " + nextNumber + " = " + result);
                    System.out.println ("update the result = " + result);
Edited by: shadowjuan450 on Oct 28, 2008 8:20 AM

Answer 1

What trouble are you having? Is it not compiling? Throwing errors? Not doing what you expected?
Also: Use the "CODE" tags when posting code, it makes it much easier to read.
Lastly: Find a specific area in the code you're having trouble with, and ask directed questions about that specific area.