Jtabbedpane using multiple classes

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.

Answer 2

You state:

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.

An ActionListener won't work if your desire is to listen for change in selected tab since this is activated only by the children of the AbstractButton class. Instead note that a JTabbedPane uses a SingleSelectionModel as its model, and you can listen for changes to this with ChangeListener. The API and tutorials can help fill in the details.

If on the other hand you're wondering if you can use a JButton/ActionListener within one component held by a tab and have the actions cause changes in another component held on another tab, then the answer is certainly, even if the two views are created by different classes. This is where the observer or listener design pattern comes to fore. For details on this, give more details of your specific problem.

Also I strongly agree with brano88 -- don't use a window builder program until you are quite familiar and in fact well grounded in the rudiments of the Swing library.