Question

Here is come code to demo my problem:
Parent class:

    import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class PPanel extends JPanel{
    private APanel panel1;
    private APanel panel2;
    private APanel panel3;
    public PPanel() {
        this.setLayout(new GridLayout(0,1));
        panel1 = new APanel();
        panel1.setLayout(new GridLayout(0,1));

        panel2 = new APanel();
        panel2.setBackground(Color.yellow);
        panel2.setLayout(new GridLayout(0,1));
        panel3 = new APanel();
        panel3.setBackground(Color.green);
        //panel3.setLayout(new GridLayout(0,1));
        this.add(panel1);
        this.add(panel2);
        this.add(panel3);
        this.setBackground(Color.blue);
        this.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("Parent panel clicked!");
            }               
        });
    }
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        PPanel panel = new PPanel();
        frame.add(panel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(new Dimension(350, 300));
        frame.setTitle("Demo");
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

Child panel class:

import java.awt.Color;
import java.awt.Component;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class APanel extends JPanel{
    private JTextField tf;
    public APanel() {
        tf = new JTextField("Double click");
        tf.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("Textfiled");
                Component source = (Component) e.getSource();
                System.out.println(source.getParent());
                source.getParent().dispatchEvent(e);
            }
        });
        this.add(tf);
        this.setVisible(true);
        this.setBackground(Color.red);

        this.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("Child panel clicked!");
                Component source = (Component) e.getSource();
                System.out.println("Parent container of APanel is " + source.getParent());
                if(source.getParent() instanceof PPanel)
                    source.getParent().dispatchEvent(e);
            } 
        });
    }
}

I was hoping that once a mouseClicked event triggered in the JTextField, it will be propagated to the parent panel by using dispatchEvent. But for child panel that have JTextField, it seems that the MouseClicked event only gets to APanel. Then it prints parent of APanel is APanel!. So it appears to me that dispatchEvent only sends event to next immediate container and no more.

How can I solve this? Is there a way I can dispatch an event directly to another container?

Answer 1

You’re seeing this behavior because MouseEvent#getSource() returns the JTextField, whose parent is the APanel. You were expecting getSource() to return APanel.

It looks like you could achieve the desired effect by calling getParent().getParent() to go up another level. Do keep in mind that this is a very brittle and poor solution because it will break if you decide that you need another component between your APanel and its JTextField.

Perhaps you can use a recursive approach to walk up the component hierarchy, calling getParent() until you’ve reached a PPanel, at which point you can call dispatchEvent.