Making a simple calc applet. Where am I going wrong?

Question

Hi everyone. I'm taking a introductory java class over the summer and so far I've been doing pretty good in it. I've been able to knock out and figure out how to do most of the assignments on my own. But this latest problem is driving me up a wall. I think I might be making it more difficult then it is. I'm supposed to a take a simple calculation program, and then convert it into an applet with new button functionality and text fields. In the applet, there will be two text fields(input and result) and two buttons(Update and Reset). In the first field you put in an operator and a number. Then from there you hit the Update button and the new value is put in the second field.
For example. The program is defaulted to "0". So you put "+ 9" in the first field, then Hit Update. "9" will now appear in the second field. Go back to the first field and put in "- 3", hit update again and now the second field will go to "6." You can keep doing this all you want. Then when you want to start all over again you hit reset. Its sort of a weird program.
Here's the original calc program:
import java.util.Scanner;
Simple line-oriented calculator program. The class
can also be used to create other calculator programs.
public class Calculator
    private double result;
    private double precision = 0.0001; // Numbers this close to zero are
                                       // treated as if equal to zero.
    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 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 Calculator( )
        result = 0;
    public void reset( )
        result = 0;
    public void setResult(double newResult)
        result = newResult;
    public double getResult( )
        return result;
     The heart of a calculator. This does not give
     instructions. Input errors throw exceptions.
    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
                double nextNumber = keyboard.nextDouble( );
                result = evaluate(nextOp, result, nextNumber);
                System.out.println("result " + nextOp + " " +
                                   nextNumber + " = " + result);
                System.out.println("updated result = " + result);
     Returns n1 op n2, provided op is one of '+', '-', '*',or '/'.
     Any other value of op throws UnknownOpException.
    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 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);
}Here's me trying to make it into an applet with the added button functionality.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.math.*;
import java.util.*;
import java.io.*;
import java.lang.*;
public class Calculator extends JApplet implements ActionListener
          // Variables declaration. 
           private javax.swing.JPanel jPanel2;
         private javax.swing.JLabel jLabel2;
         private javax.swing.JTextField jTextField1;
         private javax.swing.JLabel jLabel3;
         private javax.swing.JTextField jTextField2;
         private javax.swing.JButton jButton1;
         private javax.swing.JButton jButton2;
         private javax.swing.JTextArea resultArea;
         private Container container;
         // End of variables declaration
     public void init () {
        initComponents();    
        setSize(400, 200);       
    private void initComponents() {
        container = getContentPane();
        container.setLayout( new BorderLayout() );
            // Creating instances of each item 
            jPanel2 = new javax.swing.JPanel();
        jLabel2 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        jTextField2 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        resultArea = new javax.swing.JTextArea();
            // End Creation
        // Set text on labels, preferred size can be optional on labels,
            // size should/must be used on text fields.
          // Then each individual item is added to a panel.
        jLabel2.setText("Input =");
        jPanel2.add(jLabel2);
        jTextField1.setText("");
        jTextField1.setPreferredSize(new java.awt.Dimension(65, 20));
        jPanel2.add(jTextField1);
        container.add( jPanel2, BorderLayout.SOUTH);
        jButton1.setText("Update");
            jButton1.addActionListener(this);
            jButton2.setText("Reset");
            jButton2.addActionListener(this);
            container.add(resultArea, BorderLayout.CENTER);
        container.add(jButton1, BorderLayout.WEST);
        container.add(jButton2, BorderLayout.EAST);
                 resultArea.setText("Calculator is on.\n" +
                         "Format of each line: " +
                                         "\noperator space number" +
                         "\nFor example: + 3" +
                                         "\nThen hit Update to compute"+
                         "\nHit Reset to set the result back to zero.");
   private double result;
   private double precision = 0.0001;
   public void actionPerformed(ActionEvent e)
            Calculator clerk = new Calculator( );
        try
            clerk.doCalculation();
            catch(UnknownOpException e2)
            clerk.handleUnknownOpException(e2);
        catch(DivideByZeroException e2)
            clerk.handleDivideByZeroException(e2);
        resultArea.setText("The final result is " + clerk.getResult( )+
                                    "\nCalculator program ending.");
     public Calculator( )
        result = 0;
    public void reset( )
        result = 0;
    public void setResult(double newResult)
        result = newResult;
    public double getResult( )
        return result;
     The heart of a calculator. This does not give
     instructions. Input errors throw exceptions.
    public void doCalculation( ) throws DivideByZeroException,
                                        UnknownOpException
        Scanner keyboard = new Scanner(System.in);
        boolean done = false;
        result = 0;
        resultArea.setText("result = " + result);
        while (!done)
           char nextOp = (keyboard.next( )).charAt(0);
            if ((nextOp == 'e') || (nextOp == 'E'))
                done = true;
            else
                double nextNumber = keyboard.nextDouble( );
                result = evaluate(nextOp, result, nextNumber);
                resultArea.setText("result " + nextOp + " " + nextNumber + " = " + result+
                                                "\nupdated result = " + result);
     Returns n1 op n2, provided op is one of '+', '-', '*',or '/'.
     Any other value of op throws UnknownOpException.
    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 handleDivideByZeroException(DivideByZeroException e)
        resultArea.setText("Dividing by zero."+
                           "\nProgram aborted");
        System.exit(0);
    public void handleUnknownOpException(UnknownOpException e)
        resultArea.setText(e.getMessage( )+
                          "\nTry again from the beginning:");
        try
            resultArea.setText("Calculator is on.\n" +
                         "Format of each line: " +
                                         "\noperator space number" +
                         "\nFor example: + 3" +
                         "\nHit Reset to set the result back to zero.");
                    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);
}I'm not getting any compiling errors or anything and it launches, but it doesn't work at all. I'm sure it has something to do with the calc program and the applet actionevent. I just don't know where to go from there. Can anyone tell me where I'm going wrong? Or even make sense of what I've posted. I know its a lot. I've been looking at this thing for a day now and its killing me. Any help would be greatly appreciated. Thanks.

Answer 1

This is a mistake
public void actionPerformed(ActionEvent e)
            Calculator clerk = new Calculator( );
        try
            clerk.doCalculation();You don't want to create a whole new applet every time anyone pushes a button.
Make whatever changes are neccessary so that you don't have to create a new applet in your actionPerformed