I am a beginner in Eclipse. I have to do a program called calculator that adds numbers. This is my code so far:

//Margaret //ICS 4U /* * Created on Apr 29, 2011 * * TODO To change the template for this generated file go to * Window - Preferences - Java - Code Style - Code Templates */

/** * @author 301687257 * * TODO To change the template for this generated type comment go to * Window - Preferences - Java - Code Style - Code Templates */

import java.awt.*; import java.awt.event.*; import javax.swing.*;

public class Calculator extends JFrame implements ActionListener { JTextField text = new JTextField (20); Button b, b2, b3, b4, b5, b6, b7, b8, b9, c, c2, c3, c4;

private int numClicks = 0; 
int num, num1, num2, num3 = 2; 
int counter = 0;
String numbers = ""; 
String sum = "";
double mainNum;
int operation = 1; 
int temp = 1; 

//Constructor
public Calculator (String Title){
    super (Title);
    setSize(200, 300);
    setLayout (new FlowLayout ());
    b = new Button("Clear");
    add (b);
    add (text);
    b.addActionListener(this);
    b2 = new Button("1");
    add (b2);
    add (text); 
    b2.addActionListener(this);
    b3 = new Button ("2");
    add (b3);
    add (text); 
    b3.addActionListener(this);
    b4 = new Button ("3");
    add (b4);
    add (text);
    b4.addActionListener(this);
    b5 = new Button ("4");
    add (b5);
    add (text);
    b5.addActionListener(this);
    b6 = new Button ("5");
    add (b6);
    add (text);
    b6.addActionListener(this);
    b7 = new Button ("6");
    add (b7);
    add (text);
    b7.addActionListener(this);
    b8 = new Button ("7");
    add (b8);
    add (text);
    b8.addActionListener(this);
    b9 = new Button ("8");
    add (b9);
    add (text);
    b9.addActionListener(this);
    c = new Button ("9");
    add (c);
    add (text);
    c.addActionListener(this);
    c2 = new Button ("0");
    add (c2);
    add (text);
    c2.addActionListener(this);
    c3 = new Button ("+");
    add (c3);
    add (text);
    c3.addActionListener(this);
    c4 = new Button ("=");
    add (c4);
    add (text);
    c4.addActionListener(this);

}


/* (non-Javadoc)
 * @see java.awt.event.ActionListener#actionPerformed(java.awt.event.ActionEvent)
 */
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub
    //   TODO Auto-generated method stub


    if (counter == 0)
        num1 = num;
    counter++; 
    if (counter == 1)
        num2 = num1;
    counter++; 

    if (e.getSource()==b)
        text.setText("0.");
    else if (e.getSource()==b2)
        //System.out.println ("1");
        text.setText("1");
    else if (e.getSource()==b3)
        text.setText("2");
    else if (e.getSource()==b4)
        text.setText("3");
    else if (e.getSource()==b5)
        text.setText("4");
    else if (e.getSource()==b6)
        text.setText("5");
    else if (e.getSource()==b7)
        text.setText("6");
    else if (e.getSource()==b8)
        text.setText("7");
    else if (e.getSource()==b9)
        text.setText("8");
    else if (e.getSource()==c)
        text.setText("9");
    else if (e.getSource()==c2)
        text.setText("0");
    else if (e.getSource()==c3)
        text.setText("+");
    else if (e.getSource () == c4)
        if (operation == 1)
            mainNum = mainNum + temp; 

    //text.setText(sum);

    counter++;
    //System.out.println (num); 
    num1 = num;
    num2 = num3; 

}

public static void main(String[] args) {
    Calculator myWindow = new Calculator("Calculator");
    myWindow.setVisible(true);
}

}

I am having trouble making the equal button give the answer when two buttons are pressed. Can someone help me with this? Thanks.