How to make java dispatch mouse events to my component

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Nomak - 29 Oct 2004 16:02 GMT

Hello,

I have a home made panel (which extend JPanel), and a home made
graphical component (which extend java.awt.Component).

What i want to do is:
- when i click on the HomePanel, it's add a HomeComponent to it.
- when i click on a HomeComponent in the HomePanel, it change it's
color.

Right now, my code is:

// the HomePanel
public class HomePanel extends JPanel {
}

// the HomeComponent
public class HomeComponent extends Component
implements MouseListener {
public void paint(Graphics g) {
...
}

public void mousePressed(MouseEvent e) {
System.err.println("DEBUG: HomeComponent.mousePressed");
}

...
}

// and the MainFrame:
public class MainFrame extends javax.swing.JFrame {
...
// generated code
homePanel.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent evt) {
homePanelMousePressed(evt);
}
});
getContentPane().add(homePanel);
...

private void homePanelMousePressed(java.awt.event.MouseEvent evt){
System.err.println("DEBUG: MainFrame.homePanelMousePressed");
homePanel.add(new HomeComponent());
homePanel.repaint();
}
}

1/ Why does it don't work?
2/ What is the interest of MouseAdaptater(s) over MouseListener(s)?

Thanks for your help.

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Nomak

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Andrew Thompson - 29 Oct 2004 17:17 GMT

> I have a home made panel (which extend JPanel), and a home made
> graphical component (which extend java.awt.Component).

Mixing light and heavywieght components can be problematic.
Until you have a lot of experience with both and are familiar
with why, you should avoid doing it.
<http://www.physci.org/guifaq.jsp#5.1>

> What i want to do is:
> - when i click on the HomePanel, it's add a HomeComponent to it.
> - when i click on a HomeComponent in the HomePanel, it change it's
> color.
>
> Right now, my code is:

...

> 1/ Why does it don't work?

Several ways to answer this..
a) It must compile first.
b) Define 'work'
c) Try flogging it wiyh a whip. It may just be lazy. ;-)

Now, here is some code that copy/pasted into a file named
'MainFrame.java' will compile and run..

<sscce>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

// the HomePanel
class HomePanel extends JPanel {
}

// the HomeComponent
class HomeComponent extends Component
implements MouseListener {
public void paint(Graphics g) {
// ...
}

public void mousePressed(MouseEvent e) {
System.err.println("DEBUG: HomeComponent.mousePressed");
}

public void mouseReleased(MouseEvent e) {
System.err.println("" + e);
}
public void mouseClicked(MouseEvent e) {
System.err.println("" + e);
}
public void mouseEntered(MouseEvent e) {
System.err.println("" + e);
}
public void mouseExited(MouseEvent e) {
System.err.println("" + e);
}
// ...
}

// and the MainFrame:
public class MainFrame extends javax.swing.JFrame {

HomePanel homePanel = new HomePanel();

MainFrame() {
// ...

// generated code
// What does that mean? generated by what?
homePanel.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent evt) {
homePanelMousePressed(evt);
}
});
getContentPane().add(homePanel);
// ...
}

private void homePanelMousePressed(java.awt.event.MouseEvent evt){
System.err.println("DEBUG: MainFrame.homePanelMousePressed");
homePanel.add(new HomeComponent());
homePanel.repaint();
}

public static void main(String[] args) {
MainFrame mainFrame = new MainFrame();
mainFrame.setSize(100,100);
mainFrame.setVisible(true);
}
}
</sscce>

It 'works' for certain values of 'works'.

> 2/ What is the interest of MouseAdaptater(s) over MouseListener(s)?

Who's interest? The code uses a MouseListener.

Signature

Andrew Thompson
http://www.PhySci.org/codes/ Web & IT Help
http://www.PhySci.org/ Open-source software suite
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Nomak - 29 Oct 2004 20:36 GMT

Le 29/10/2004 à 18:17:43, Andrew Thompson <SeeMySites@www.invalid> a
écrit:

> Mixing light and heavywieght components can be problematic.
> Until you have a lot of experience with both and are familiar
> with why, you should avoid doing it.
> <http://www.physci.org/guifaq.jsp#5.1>

thx, i switch to JComponent.

> [...]

Sorry for not being precise.

1/ I don't know why it didn't work, but know it does:

// the HomePanel
public class HomePanel extends javax.swing.JPanel {

public HomePanel() {
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent evt) {
HomePanel.this.mousePressed(evt);
}
});
}

private void mousePressed(MouseEvent evt) {
System.err.println("DEBUG: HomePanel.mousePressed");

add(New HomeComponent());
repaint();
}
}

// the HomeComponent
public class HomeComponent extends javax.swing.JComponent {

public HomeComponent() {
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent evt) {
HomeComponent.this.mousePressed(evt);
}
});
}

public void paint(Graphics g) {
...
}

public void mousePressed(MouseEvent e) {
System.err.println("DEBUG: HomeComponent.mousePressed");
}
}

// and the MainFrame:
public class MainFrame extends javax.swing.JFrame {
...
// generated by Netbeans code
getContentPane().add(homePanel);
...
}

Output:
DEBUG: MainFrame.main
DEBUG: HomePanel.mousePressed <= click on the panel
DEBUG: HomeComponent.paint
DEBUG: HomeComponent.mousePressed <= click on the component

the click on the component is not handled by the panel => success :D

2/ Adapter(s) avoid to define all the methods of Listener(s)
interface, and since Adapter are class and Java cannot multi-herit
everybody use inlive inner class definition of adapter.

Thank you and google ;)

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Nomak

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Andrew Thompson - 29 Oct 2004 20:46 GMT

> the click on the component is not handled by the panel => success :D

Excellent work, glad you sorted it.
And thanks for getting back to us.

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How to make java dispatch mouse events to my component

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