Is it possible that JButton and actionPerformed method are in different files?

Question

Is it possible to have a button on one file and its actionPerformed(ActionEvent e) method in a different file? I am trying to add an actionListener to a button, choose1 which is in file trialdump.java but the actionPerformed(ActionEvent e) method is in file listen.java. I tried extending public class trialdump extends listen but it shows an error. Any idea how I can add the method to the button? Thanks.

Here is my code in file trialdump.java:

package Core;

import javax.swing.GroupLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.*;
import java.awt.*;

// Create a simple GUI window
public class trialdump {

private static void createWindow() {

    // Create and set up the window.
    JFrame frame = new JFrame("PDF Denoiser");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // My edit
    JPanel panel = new JPanel();
    GroupLayout layout = new GroupLayout(panel);
    panel.setLayout(layout);

    layout.setAutoCreateGaps(true);
    layout.setAutoCreateContainerGaps(true);

    JLabel label1 = new JLabel("Image File");
    JLabel label2 = new JLabel("Destination");
    JLabel label3 = new JLabel("Preview");

    JTextField current = new JTextField();
    JTextField dest = new JTextField();
    JTextArea preview = new JTextArea();

    preview.setEditable(false);
    JScrollPane previewScrollPane = new JScrollPane(preview);

    JButton choose1 = new JButton("Search1");
    JButton choose2 = new JButton("Search2");
    JButton algo1 = new JButton("MDWM");
    JButton algo2 = new JButton("BFMR");
    JButton algo3 = new JButton("Mine");



    // Horizontal arrangement
    layout.setHorizontalGroup(layout
            .createSequentialGroup()
            .addGroup(
                    layout.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(label1)
                            .addComponent(label2).addComponent(label3))
            .addGroup(
                    layout.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(current)
                            .addComponent(dest).addComponent(preview))
            .addGroup(
                    layout.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(choose1)
                            .addComponent(choose2).addComponent(algo1).addComponent(algo2).addComponent(algo3)));

    layout.linkSize(SwingConstants.HORIZONTAL, choose1, choose2, algo1, algo2, algo3);

    // Vertical arrangement
    layout.setVerticalGroup(layout
            .createSequentialGroup()
            .addGroup(
                    layout.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(label1)
                            .addComponent(current).addComponent(choose1))
            .addGroup(
                    layout.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(label2)
                            .addComponent(dest).addComponent(choose2))
            .addGroup(
                    layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                            .addComponent(label3)
                            .addComponent(preview)
                            .addGroup(
                                    layout.createSequentialGroup().addComponent(algo1).addComponent(algo2)
                                            .addComponent(algo3))));

    // Display the window.
    frame.setLocationRelativeTo(null);
    frame.add(panel);
    frame.pack();
    frame.setVisible(true);
}

public static void main(String[] args) {

    createWindow();

}
}

And here is my code in listen.java:

package components;

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.SwingUtilities;
import javax.swing.filechooser.*;

public class listen extends JPanel implements ActionListener{

static private String newline = "\n";
private JTextArea log;
private JFileChooser fc;

public listen() {



}

public void actionPerformed(ActionEvent e) {
    //Set up the file chooser.
    if (fc == null) {
        fc = new JFileChooser();

    //Add a custom file filter and disable the default
    //(Accept All) file filter.
        fc.addChoosableFileFilter(new imagefilter());
        fc.setAcceptAllFileFilterUsed(false);

    //Add custom icons for file types.
        fc.setFileView(new imagefileview());

    //Add the preview pane.
        fc.setAccessory(new imagepreview(fc));
    }

    //Show it.
    int returnVal = fc.showDialog(listen.this,
                                  "Attach");

    //Process the results.
    if (returnVal == JFileChooser.APPROVE_OPTION) {
        File file = fc.getSelectedFile();

    } else {
        log.append("Attachment cancelled by user." + newline);
    }
    log.setCaretPosition(log.getDocument().getLength());

    //Reset the file chooser for the next time it's shown.
    fc.setSelectedFile(null);
}

/**
 * Create the GUI and show it.  For thread safety,
 * this method should be invoked from the
 * event dispatch thread.
 */


public static void main(String[] args) {
    //Schedule a job for the event dispatch thread:
    //creating and showing this application's GUI.
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            //Turn off metal's use of bold fonts
            UIManager.put("swing.boldMetal", Boolean.FALSE);

        }
    });
}
}

Answer 1

You can add the listener defined in another class doing something like this

JButton choose1 = new JButton("Search1");
choose1.addActionListener(new listen());

BTW, you should take care of some more bits of your code:

• Classs names should be typed in CamelCase with the first letter capital
• Use proper names for your packages
• I don't think that the main method in the listener class is making anything usefull
• There is not need at all to extend from JPanel in your listener class
• Try to avoid make empty constructor, like you are doing in listen(). At least call super(), or just, don't include it.

Answer 2

Just the sample code, you can make the changes on similar lines-

class Some extends JFrame {

    private JButton button = new JButton("Something");

    Some() {
        button.addActionListener(new MyListener());
    }
}

class MyListener implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent e) {
        // do something
    }    
}

Answer 3

The proper way of doing this is by extending the the AbstractAction class adding all your action code to it's actionPerformed method, and then passing a new instance of it to either the JButton's constructor or by calling setAction on the JButton.

Here's a link to help clear it all out for you.