Need support with JButton events

Question

I\'ve recently had a question answered about how to open a login panel in my main method in another class. Because i have not yet had any lessons in Swing yet (only basic Ja

Answer 1

But now i need it to dispose the Login frame and access another method in my main.java. How can i achieve this from inside a private method in the Login.java?

Here you have a design problem. You cannot call any frame's method because your ActionListener has its scope limited to Login panel. How to solve this? Implementing an ActionListener that has visibility enough to dispose the frame.

Note: try to avoid NetBeans GUI Builder (or any GUI builder). It's easy but you miss a lot of things than making it by your own hand. You can even write a cleaner code. But it's necessary learn about Layout Managers

Example of Code: this example illustrates the fact that you can achieve the same with less than half of lines of code.

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class Demo {    

    private void initGUI(){        

        final JTextField textField = new JTextField(20);
        final JFrame frame = new JFrame("Login");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);        

        JButton button = new JButton("Accept");        
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if("user".equals(textField.getText())){
                    frame.dispatchEvent(new WindowEvent(frame, WindowEvent.WINDOW_CLOSING));
                    // or simply frame.dispose()
                } else {
                    JOptionPane.showMessageDialog(null, "Wrong user! Keep trying.", "Login failed", JOptionPane.WARNING_MESSAGE);
                }
            }
        });

        JPanel login = new JPanel(new FlowLayout());
        login.add(new JLabel("User"));
        login.add(textField);
        login.add(button);

        frame.getContentPane().add(login);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }    

    public static void main(String[] args) {        
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Demo().initGUI();
            }
        });
    }
}

Answer 2

I've never seen someone Specify an ActionListener for a button quite like that before.. Typically you will do one of two things (AFAIK):

Implement the ActionListener in the class that contains the JButton you wish to use, then JButton.addActionListener(this) to tell the button to use this class as an ActionListener. Your actionPerformed(ActionEvent e) method will do what you want the button to do.

OR

Create a new class that implements the ActionListener class and add it as an actionListener to the JButton.

Example:

public class Example1 extends JFrame implements ActionListener
{
    JButton button1;
    JTextField field1;

    public Example1()
    {
        super();
        button1 = new JButton("Login");
        button1.addActionListener(this);

        field1 = new JTextField();

        add(button1);
        add(field1);

    }

    @Override
    public void actionPerformed(ActionEvent e)
    {
        if(e.getActionCommand().equals("Login")) //for use with multiple buttons, there are other ways to do this
            field1.setText("LOL");
    }

}

I think this is what you were looking for..