Where to put and how to use a windowlistener in swing application and invoke it with a button?

Question

I have searched many websites and the java documentations to look how I must use a window listener.

This is my problem: I want to open a new frame with a button, (this is successful) and close the previous one. I have seen how to write a window Listener but where do I put it in my code and how can I invoke this in the button handler? (start handler) Can anybody show me how? I have searched it also here and try different things.

I am very inexperienced and still must learn a lot.

Thanks in advance.

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



public class Startvenster extends JFrame {
public static void main(String[] args) {

JFrame frame = new Startvenster();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setTitle("Rekentrainer - Startvenster");
frame.setSize(450, 400);
frame.setLocationRelativeTo(null);
frame.setContentPane( new Startpaneel());
frame.pack();

} 
}


class Startpaneel extends JPanel {

private JLabel welkom_Lbl, naamLeerling_Lbl;
private JTextField naam;
private JButton start;
private Font font;
private JPanel centrumStart, begin;


public Startpaneel() {

setBackground(Color.WHITE);

begin = new JPanel();
begin.setVisible(false);
begin.setLayout(new GridLayout(8, 2));
begin.setBackground(Color.white);

centrumStart = new JPanel();
centrumStart.setBackground(Color.white);
centrumStart.setLayout(new GridLayout(3,1));

Component bovenStrut = Box.createVerticalStrut(200);

font = new Font("Dialog", Font.PLAIN, 14);
//onderdelen van het venster

welkom_Lbl = new JLabel("Vul hieronder je naam in om de rekentrainer te starten. ");
welkom_Lbl.setFont(font);

//invoer leerling
naam = new JTextField(10);
naam.setHorizontalAlignment(JTextField.CENTER);
naam.addActionListener(new StartHandler());

start = new JButton("Start");
start.addActionListener(new StartHandler());
start.setFont(font);
start.setMnemonic(KeyEvent.VK_S);

naamLeerling_Lbl = new JLabel();

centrumStart.add(welkom_Lbl);
centrumStart.add(naam);
centrumStart.add(start);
begin.add(centrumStart);

begin.add(naamLeerling_Lbl);


add(bovenStrut);
add(bovenStrut);
add(begin);
add(centrumStart);

}


class StartHandler implements ActionListener {
public void actionPerformed(ActionEvent e) {
try { 

if(e.getSource() == start || e.getSource() == naam) {
if(naam.getText().isEmpty()) {
JOptionPane.showMessageDialog(Startpaneel.this, 
"Vul je naam in alsjeblieft.",
"Fout", JOptionPane.ERROR_MESSAGE);
} else {    

String leerling = naam.getText();
Leerling.setLeerling(leerling);
Keuzevenster kz = new Keuzevenster();
kz.setVisible(true);
kz.setSize(400, 300);
kz.setLocationRelativeTo(null);
kz.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
kz.setTitle("Rekentrainer - Keuze scherm");
kz.setContentPane(new Keuzepaneel());
kz.pack();
setVisible(false);

}
}
} catch(NumberFormatException nfe) {
JOptionPane.showMessageDialog(Startpaneel.this, 
"Geen getallen invullen alsjeblieft.",
"Fout", JOptionPane.ERROR_MESSAGE);
} 

}
}
}

Answer 1

This is how I manage listeners in my code. This example is for two buttons. I follow the Model-View-Controller structure. For the Main:

public class Main {
public static void main(String[] args) {
    //create the model
    Model model = new Model();

    //create the view
    MainView view = new MainView();

    //create the controller
    MainController controller = new MainController();        

    //add controller to view
    view.listener(controller);

    //show the view
    view.setVisible(true);
    }
}

For the view:

//create buttons
private JButton firstButton;
private JButton secondButton;
//...
firstButton = new JButton("first button");
secondButton = new JButton("second button");
//add them where you wish in your view. 

//Then link the controller you added previously on them main to this two buttons:
public void listener(MainController controller) {
    firstButton.addActionListener(controller);
    secondButton.addActionListener(controller);
}

And finally in your controller, execute the code you want for each button:

public class MainController implements ActionListener{


@Override
public void actionPerformed(ActionEvent e) {
    //the following line tells you which button has been pressed
    String pressedButton = e.getActionCommand();
    switch (pressedButton){
        case "first button":
            System.out.println("First button pressed!");
            break;

        case "second button":
            System.out.println("Second button pressed!");
            break;
    }
}

}