Question

I’m fairly new to java and am creating a windowbuilder program. I am wondering if it is possible when using Jtabbedpane and switching between the tabs in the program window if i can use an actionlistener to get the contents from a separate class. For example, i have a program with two tabs and two classes, the first tab will have the code from one class and the second tab from the second class.

Thanks

Answer 1

If you want to separate your code which creates GUI, to multiple classes, you could use this aproach:

This would be your main class which will contain JTabbedPane:

import javax.swing.JFrame;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;

public class Main {
    JFrame frame = new JFrame();
    JTabbedPane tabbedPane = new JTabbedPane();
    FirstPanel fp = new FirstPanel();
    SecondPanel sp = new SecondPanel();

    public Main() {
        tabbedPane.add("First", fp);
        tabbedPane.add("Second", sp);
        frame.getContentPane().add(tabbedPane);
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setSize(640, 480);
        // frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new Main();
            }
        });
    }

}

This would be your second class which extends JPanel or some other type of container:

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;

import javax.swing.JPanel;

public class FirstPanel extends JPanel{

    public void paintComponent(Graphics g){
        g.setColor(Color.BLACK);
        g.setFont(new Font("Verdana",Font.BOLD,16));
        g.drawString("Hello there", 20, 20);
    }
}

Example of third class which also extends JPanel:

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class SecondPanel extends JPanel{
    JButton button = new JButton("Click me!");

    public SecondPanel() {
        button.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                JOptionPane.showMessageDialog(null, "You just clicked button");
            }
        });
        add(button);
    }

    public void paintComponent(Graphics g){
        g.setColor(Color.BLACK);
        g.setFont(new Font("Verdana",Font.BOLD,16));
        g.drawString("Hello there again!", 20, 20);
    }
}

Screenshot:

EDIT:

Also, instead of extending classes with JPanel, it would be wise to create just a method in that class which returns customized JPanel. This way your class stays “opened” for inheritance.