[Crunch]

Anna, on 22 August 2010 - 12:27 AM, said:

Need help asap!! My final is due tomorrow I have been glued to it all week and cant seem to figure out how to fix it... it doesnt show the results...please help me!!!!

What errors do you get ? How does your output differ from the expected output ?

[Luckless]

also, what is it supposed to do? I'm not going to piece it together.

[guahguahmonster]

Anna, on 21 August 2010 - 05:39 PM, said:

I am not getting any errors but it isnt doing what is suppose to be done when the button is pressed. It acts like I never hit the button.

Doesn't this make you suspicious in any way? If NONE of your buttons are working, and you're quite sure nothing else is wrong with your code, there are no errors, and it compiles fine, then it's a great guess to say that something is wrong with your ActionListeners, because ActionListeners are in charge of executing code when "stuff happens".

A short explanation of what's wrong in your code. For all of your calls to addActionListener, you attempt to add this (a FinalProject) as the ActionListener. So that means the actionPerformed method of the FinalProject is called whenever you click a button. But what's the actionPerformed method of the FinalProject? It's completely blank. So when you click the button, nothing happens, because that's what you programmed it to do.

Instead, littered throughout your FinalProject constructor are numerous statements of the form new ActionListener{ /* definition here */ };. These are useless because these ActionListeners are being created and then immediately discarded (nobody's keeping a reference to them!) Here's one example of the offending code I'm talking about:

// ALERT! THIS CODE IS INCORRECT! DO NOT USE!!!
public class FinalProject extends JFrame implements ActionListener {
    // Code omitted...
    public FinalProject() {
        // Code omitted...

        // Okay, so this adds a FinalProject as the button's ActionListener...
        button.addActionListener(this);
        
        // Incorrect code! This ActionListener gets discarded instantly!
        new ActionListener(){
            public void actionPerformed(ActionEvent e) {
                int length=Integer.parseInt(text4.getText());
                int width=Integer.parseInt(text5.getText());
                int depth=Integer.parseInt(text6.getText());
                
                if (e.getActionCommand().equals("Enter")) {
                    int volume = ((length * width) * depth);
                    JOptionPane.showMessageDialog(null, "The Volume is:"+volume,"for your pool.", JOptionPane.INFORMATION_MESSAGE);
                }
                }
        };
    }

    // Incorrect code! This method is empty!!!
    public void actionPerformed(ActionEvent e) {
         // TODO Auto-generated method stub
    }
}

I can think of a few options to fix this (there may be more, but these are the simplest). These first two examples show how to change the above incorrect code to be correct.

1. Pass anonymous classes to addActionListener.

public class FinalProject extends JFrame implements ActionListener {
    // Code omitted...
    public FinalProject() {
        // Code omitted...

        // Add an anonymous class as an ActionListener.
        button.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e) {
                int length=Integer.parseInt(text4.getText());
                int width=Integer.parseInt(text5.getText());
                int depth=Integer.parseInt(text6.getText());
                
                if (e.getActionCommand().equals("Enter")) {
                    int volume = ((length * width) * depth);
                    JOptionPane.showMessageDialog(null, "The Volume is:"+volume,"for your pool.", JOptionPane.INFORMATION_MESSAGE);
                }
            }
        });
    }
}

2. Make inner classes in FinalProject, instantiate them and pass them to addActionListener.

public class FinalProject extends JFrame implements ActionListener {
    // Code omitted...

    // Make an inner class to act as an ActionListener later on.
    private class ButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            // NB: text{4, 5, 6} have to be class variables of FinalProject
            int length=Integer.parseInt(text4.getText());
            int width=Integer.parseInt(text5.getText());
            int depth=Integer.parseInt(text6.getText());
            
            if (e.getActionCommand().equals("Enter")) {
                int volume = ((length * width) * depth);
                JOptionPane.showMessageDialog(null, "The Volume is:"+volume,"for your pool.", JOptionPane.INFORMATION_MESSAGE);
            }
        }
    }

    public FinalProject() {
        // Code omitted...

        // Instantiate the previously defined inner class,
        // and add that as an ActionListener
        button.addActionListener(new ButtonListener());
    }
}

Note that if you do this you can make more than one inner class, which makes sense as your ActionListeners are all different in some way.

3. Actually define actionPerformed of FinalProject. This is not easy because you need at least 6 different ActionListeners doing different things and therefore it's probably just eaiser to use anonymous classes or inner classes.

Hope this all made sense. Feel free to ask for clarification. Good luck.

This post has been edited by guahguahmonster: 22 August 2010 - 12:24 AM

[pbl]

guahguahmonster, on 22 August 2010 - 01:04 AM, said:

1. Pass anonymous classes to addActionListener.

public class FinalProject extends JFrame implements ActionListener {
    // Code omitted...
    public FinalProject() {
        // Code omitted...

        // Add an anonymous class as an ActionListener.
        button.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e) {
                int length=Integer.parseInt(text4.getText());
                int width=Integer.parseInt(text5.getText());
                int depth=Integer.parseInt(text6.getText());
                
                if (e.getActionCommand().equals("Enter")) {
                    int volume = ((length * width) * depth);
                    JOptionPane.showMessageDialog(null, "The Volume is:"+volume,"for your pool.", JOptionPane.INFORMATION_MESSAGE);
                }
            }
        });
    }
}

When using anonymous class no need to check for the actionCommand: can only be the actual button