Question

This question probably belies underlying lack of Swing knowledge, but I can’t seem to pin down what I’m doing wrong. Essentially I want to detect mousePressed in one component, and then receive the mouseReleased for whatever component is under the mouse when it is released, rather than the original component.

import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.event.MouseInputAdapter;
import net.miginfocom.swing.MigLayout;

public class TestMouseListener extends MouseInputAdapter {

    public void mouseEntered(MouseEvent arg0) {System.out.println("Entered " + arg0.getComponent());}
    public void mouseExited(MouseEvent arg0) {System.out.println("Exited " + arg0.getComponent());}
    public void mousePressed(MouseEvent arg0) {System.out.println("Pressed " + arg0.getComponent());}
    public void mouseReleased(MouseEvent arg0) {System.out.println("Released " + arg0.getComponent());}

    public static void main(String[] args){
        JFrame frame = new JFrame();
        frame.setLayout(new MigLayout());
        frame.setSize(400, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        TestPanel panel1 = new TestPanel("Panel 1");
        TestPanel panel2 = new TestPanel("Panel 2");
        panel1.add(new JLabel("Text1"));
        panel2.add(new JLabel("Text2"));
        frame.add(panel1);
        frame.add(panel2);
        TestMouseListener listener = new TestMouseListener();
        panel1.addMouseListener(listener);
        panel1.addMouseMotionListener(listener);
        panel2.addMouseListener(listener);
        panel2.addMouseMotionListener(listener);
        frame.setVisible(true);
    }
}
class TestPanel extends JPanel {
    String name;
    TestPanel(String name){ this.name = name; }
    public String toString(){ return name; }
}

So when I mouse over panel 1, click, drag to panel 2, release, I get the following:

Entered Panel 1
Pressed Panel 1
Exited Panel 1
Entered Panel 2
Released Panel 1

How do I get the panel I released over? I was hoping the mouseReleased event would fire for Panel 2 but obviously it does not.

Answer 1

Store a variable that holds your most recently entered component. Keep overwriting it every time you trigger a MouseEntered event. Then have a method, so that when you release the mouse button, you can use whatever your most recently entered component is.

Component lastEntered;

private void MouseEntered(MouseEvent e) {
    lastEntered = e.getComponent;
}