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KeyListener will not respond to keyboard input [duplicate]

This question already has answers here:
Keylistener not working for JPanel
(4 answers)
Closed 8 months ago.
I am trying to add a JPanel to a JFrame. The JPanel is supposed to listen to keyboard input and mouse input. When i open the window it does work for the mouse but the keyboard gets ignored and i just can't see the problem, since i wrote the same stuff for both Listeners.
This is the code for the Panel
public class testjpanel extends JPanel implements MouseListener,KeyListener {
testjpanel (){
this.addMouseListener(this);
this.addKeyListener(this);
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
System.out.println(1);
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
System.out.println(1);
}
#Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
}
and here is the rest
public class main extends JFrame {
public main() {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(500,500);
this.setVisible(true);
this.setLayout(null);
testjpanel a= new testjpanel();
a.setVisible(true);
a.setBounds(0,0,500,500);
a.setLayout(null);
this.add(a);
}
}

This is a rather non-standard way to use a keyboard or mouse listener. A better, consistently reliable way is as follows.
Create a class to be your MouseManager:
public class MouseManager implements MouseListener {
#Override
public void mouseClicked(MouseEvent arg0) {
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent arg0) {
}
#Override
public void mouseReleased(MouseEvent arg0) {
}
}
And the Keyboard Manager:
public class KeyboardManager implements KeyListener {
#Override
public void keyPressed(KeyEvent arg0) {
}
#Override
public void keyReleased(KeyEvent arg0) {
}
#Override
public void keyTyped(KeyEvent arg0) {
}
}
After this, all you have to do is add them to your window like this below example:
public class MyFrame extends JFrame {
public MyFrame() {
this.setTitle("Your title");
this.setSize(new Dimension(500, 500));
this.addMouseListener(new MouseManager())
this.addKeyListener(new KeyboardManager());
}
}
Having the keyboard and mouse managers/listener in their own classes keeps things tidy and makes them easier to work with; for functionality, add them to the JFrame instead of your JPanel.

Capture JFrame resize only once, when mouse is released

I am trying to capture the moment a user finished resizing a JFrame through the mouse drag of a frame corner. I have so far found the below options, but they both print BLAH again and again until I am done stretching the window size. I only want it to print BLAH once I released the mouse after the continuous dragging of the JFrame corner resizing it. Any thoughts?
frame.addComponentListener(new ComponentAdapter()
{
public void componentResized(ComponentEvent evt) {
Component c = (Component)evt.getSource();
System.out.println("BLAH");
}
});
AND
frame.addComponentListener(new ComponentListener() {
#Override
public void componentShown(ComponentEvent e) {
// TODO Auto-generated method stub
}
#Override
public void componentResized(ComponentEvent e) {
// TODO Auto-generated method stub
System.out.println("BLAH");
}
#Override
public void componentMoved(ComponentEvent e) {
// TODO Auto-generated method stub
}
#Override
public void componentHidden(ComponentEvent e) {
// TODO Auto-generated method stub
}
}
);

The core problem is, you're unlikely to be able to detect when a mouse event occurs on the frame decorations, as it tends to be handled at a much lower level.
One trick I've used in the past, is to use a short lived, single run, Swing Timer, which is restarted each time componentResized is called. This means that the Timer will only trigger AFTER a "short delay" after componentResized stops been called, for example
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel label;
private Timer resizeTimer;
public TestPane() {
setLayout(new GridBagLayout());
label = new JLabel(".......");
add(label);
addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
if (resizeTimer == null) {
resizeTimer = new Timer(250, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
label.setText(getSize().width + "x" + getSize().getHeight());
resizeTimer.stop();
resizeTimer = null;
}
});
resizeTimer.setRepeats(false);
}
resizeTimer.restart();
}
});
}
}
}

How to create a class that implements mouseListener

I want to create a class that implement mouseListener interface (this class will override all mouseListener methods) instead of override all the methods in the main class. When I tring to do so I get an error.
This is my code:
import javax.swing.*;
public class Game {
public Game(){
JFrame frame = new JFrame();
frame.setSize(500,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addMouseListener(new MyMouseListener());
}
public static void main(String[] args) {
Game app = new Game();
}
}
MyMouseListener code:
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class MyMouseListener implements KeyListener{
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
}
edit: I understand my problem was that I implement keyListener insteed of mouseListener in the class MyMouseListener so I changed this and MyMouseListener code is now:
public class MyMouseListener extends Game implements MouseListener{
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
}

The problem you might be having is the frame not showing up, this is because you did not tell it to show the frame, use the following method:
frame.setVisible(true);
In addition as stated by Jorn Vernee, in your class MyMouseListener you have to implement the MouseListener interface instead of the KeyListener.
I tried this code out and it worked just fine:
import javax.swing.JFrame;
public class Game {
public Game(){
JFrame frame = new JFrame();
frame.setSize(500,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addMouseListener(new MyMouseListener());
frame.setVisible(true);
}
public static void main(String[] args) {
Game app = new Game();
}
}
Code for MyMouseListener:
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
public class MyMouseListener implements MouseListener{
#Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
System.out.println("clicked");
}
#Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
}

Change image to another image when clicked

I want to change my blankCardPic to clubsAcePic after I clicked on the blankCardPic and after 2 seconds, it will change back from clubsAcePic to blankCardPic. I know it could be easily done by using JLabels but I want to learn how to use paintComponent to do it.
Right now, when I clicked on the blankCardPic it does not change to clubsAcesPic.
Please help. thank you.
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class GameUI extends JPanel implements MouseListener {
/**
*
*/
private static final long serialVersionUID = 8525183729697452509L;
private boolean clicked = false;
private JFrame frame;
private BufferedImage blankCardPic;
private BufferedImage clubsAcePic;
public GameUI() {
loadImages();
frame = new JFrame();
frame.setContentPane(this);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.pack();
frame.setSize(800,600);
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setVisible(true);
}
public static void main(String[] args) {
new GameUI();
}
public void loadImages() {
try {
blankCardPic = ImageIO.read(getClass().getResourceAsStream("resources/images/blank.png"));
clubsAcePic = ImageIO.read(getClass().getResourceAsStream("resources/images/clubsAce.png"));
} catch (IOException e) {
e.printStackTrace();
}
}
public BufferedImage blankCard() {
try {
blankCardPic = ImageIO.read(new File("resources/images/blank.png"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return blankCardPic;
}
public BufferedImage revealClubsAce() {
try {
clubsAcePic = ImageIO.read(new File("resources/images/clubsAce.png"));
} catch (IOException e) {
e.printStackTrace();
}
return clubsAcePic;
}
private void render(Graphics g) {
if (!clicked) {
g.drawImage(blankCardPic, 100,100, null);
} else {
g.drawImage(clubsAcePic, 100,100, null);
}
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
render(g);
Toolkit.getDefaultToolkit().sync();
}
#Override
public void mouseClicked(MouseEvent e) {
setFocusable(true);
requestFocus();
addMouseListener(this);
if(e.getButton() == MouseEvent.BUTTON1) {
clicked = true;
repaint();
}
SwingUtilities.invokeLater(new Runnable() {
#Override public void run() {
clicked = false;
}
});
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent arg0) {
}
#Override
public void mouseReleased(MouseEvent arg0) {
}
}

Event that gets fired when a JInternalFrame is maximized/minimized

I have written the following code to handle an event incase a Jinternalframe is minimized or maximized.
jif.addComponentListener(new ComponentListener() {
public void componentResized(ComponentEvent e) {
Boolean isMax = ((JInternalFrame)e.getComponent()).isMaximum();
if(isMax == false)
{
// TODO Auto-generated method stub
}
else if(isMax == true )
{
// TODO Auto-generated method stub
}
}
public void componentMoved(ComponentEvent e) {
// TODO Auto-generated method stub
}
public void componentShown(ComponentEvent e) {
// TODO Auto-generated method stub
}
public void componentHidden(ComponentEvent e) {
// TODO Auto-generated method stub
}
}
);
The problem is that the isMax part gets triggered when the frame loads. I want this event to happen only after the Jinternalframe is completely loaded. Also i have noticed this event triggers when i minimize the container applet.
Is there any workaround for this?

You might be able to use a PropertyChangeListener and InternalFrameListener:
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import javax.swing.*;
import javax.swing.event.*;
public class InternalFrameEventTest {
public JComponent makeUI() {
final JDesktopPane desktop = new JDesktopPane();
JPanel p = new JPanel(new BorderLayout());
p.add(desktop);
p.add(new JButton(new AbstractAction("New") {
#Override public void actionPerformed(ActionEvent e) {
JInternalFrame f = new JInternalFrame("title", true, true, true, true);
InternalFrameHandler handler = new InternalFrameHandler();
f.addInternalFrameListener(handler);
f.addPropertyChangeListener(handler);
f.setSize(240, 120);
f.setVisible(true);
desktop.add(f);
}
}), BorderLayout.NORTH);
return p;
}
public static void main(String... args) {
EventQueue.invokeLater(new Runnable() {
#Override public void run() {
createAndShowGUI();
}
});
}
public static void createAndShowGUI() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
f.getContentPane().add(new InternalFrameEventTest().makeUI());
f.setSize(320, 240);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class InternalFrameHandler implements PropertyChangeListener, InternalFrameListener {
//PropertyChangeListener
#Override public void propertyChange(PropertyChangeEvent e) {
if (JInternalFrame.IS_MAXIMUM_PROPERTY.equals(e.getPropertyName())) {
System.out.println("isMaximum: " + e.getNewValue());
}
}
//InternalFrameListener
#Override public void internalFrameClosing(InternalFrameEvent e) {
System.out.println("internalFrameClosing");
}
#Override public void internalFrameClosed(InternalFrameEvent e) {
System.out.println("internalFrameClosed");
}
#Override public void internalFrameOpened(InternalFrameEvent e) {
System.out.println("internalFrameOpened");
}
#Override public void internalFrameIconified(InternalFrameEvent e) {
System.out.println("internalFrameIconified");
}
#Override public void internalFrameDeiconified(InternalFrameEvent e) {
System.out.println("internalFrameDeiconified");
if (e.getInternalFrame().isMaximum()) {
System.out.println("isMaximum: " + e.getInternalFrame().isMaximum());
}
}
#Override public void internalFrameActivated(InternalFrameEvent e) {
System.out.println("internalFrameActivated");
}
#Override public void internalFrameDeactivated(InternalFrameEvent e) {
System.out.println("internalFrameDeactivated");
}
}