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Java Focus Event Listener

I was wondering how to add a focus gained event listener.
At the moment I have a Mouse Event which is being added to my
JTextareas
//=======================================================
// mouse drag event
//=======================================================
public static class genDrag extends MouseMotionAdapter {
JTextArea textarea;
// receive textarea as argument
public genDrag(JTextArea argTextarea) {
textarea = argTextarea;
}
// add drag functionality to argument
public void mouseDragged(MouseEvent E) {
Point p = SwingUtilities.convertPoint(textarea, E.getPoint(), gc_gui.cv_content);
textarea.setBounds((p.x - 40), (p.y - 15), 100, 30);
}
}
which I can then call using
//=======================================================
// apply mouse event
//=======================================================
JTextArea textarea = new JTextArea();
textarea.setBounds(50, 50, 100, 30);
textarea.addMouseMotionListener(new genDrag(textarea));
this works fine but I have been unable to reproduce the same
functionality for a focusGained event
//=======================================================
// mouse focus event
//=======================================================
public static class genFocus extends EventListener {
JTextArea textarea;
public genFocus() {
textarea = argTextarea;
}
public void focusGained(FocusEvent E) {
System.out.println("Focus Triggered");
}
}
The above doesn't seem happy at all
UPDATING CODE
static gui classGui;
public static void main(String[] args) {
classGui = new gui();
classGui.textarea.addMouseMotionListener(
new genDrag(classGui.textarea)
);
classGui.textarea.addFocusListener(
new genFocus(this)
);
classGui.frame.setVisible(true);
public static class gui {
JFrame frame;
JPanel panel;
JTextArea textarea;
public gui() {
frame = new JFrame();
// configure JFrame here
panel = new JPanel();
// configure JPanel here
textarea = new JTextArea();
textarea.setBounds(50, 50, 100, 30);
frame.add(textarea);
}
}
public static class genDrag extends MouseMotionAdapter {
JTextArea textarea;
public genDrag(JTextArea argTextarea) {
textarea = argTextarea;
}
public void mouseDragged(MouseEvent E) {
Point p = SwingUtilities.convertPoint(textarea, E.getPoint(), gc_gui.cv_content);
textarea.setBounds((p.x - 40), (p.y - 15), 100, 30);
}
}
public static class genFocus implements FocusListener {
JTextArea textarea;
public genFocus(JTextArea argTextarea) {
textarea = argTextarea;
}
public void focusGained(FocusEvent E) {
System.out.println("Focus gained");
}
public void focusLost(FocusEvent E) {
System.out.println("Focus lost");
}
}
}

To handle focus events, your handler needs to implement the FocusListener interface instead of EventListener.
Note that you need to add this handler via the addFocusListener. I don't think you did this, because if you had done this, you would have gotten a compiler error indicating what was wrong.
Use of the #Override annotation helps finding such errors. Put it above every method you think should override a parent method. If such a method does not actually override another method, the compiler will throw an error. This way you get informed of the mistake instead of your program failing silently.

you should add a event-listener to the control JTextArea then only it will be able to handle any event request.
JTextField textarea= new JTextField("Value");
textarea.addFocusListener(new genFocus(textarea)); //this peice of code will add an listener to you textarea Object of JTextField.
Your Mouse Listener will work because you have added a mouse event listener to your JTextArea.
textarea.addMouseMotionListener(new genDrag(textarea));//code to add MouseMotionListener.
but there is no FocusEvent is registerd with your JTextArea.
Thanks.

I think this is exactly what you need...
Just a hint: your class genFocus (prefer to follow code conventions: GenFocus) should implement FocusListener.

JPanel doesn't want to focus so KeyAdapter doesn't work

Background
I had a simple game. I had one JPanel class and there were every thing (menu, game, game end).
Then I decided, that I should make my game better and I made two panels(one for menu, and second for game lvls).
Every thing were good, but my KeyAdapter class doesn't work at my JPanel. I don't know why it doesn't want to focus.
There is what I have:
Main class which extends JFrame and here I add my panels (and KeyListener to first panel)
public class JavaGame2 extends JFrame {
public JavaGame2(){
gamePanel = new GamePanel();
menuPanel = new MenuPanel();
setContentPane(menuPanel);
menuPanel.addKeyListener(new KeyListener() {
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_UP) {
menuPanel.changeCursor();
}
if (e.getKeyCode() == KeyEvent.VK_DOWN) {
menuPanel.changeCursor();
}
if (menuPanel.getCursorPos()==1){
if ((e.getKeyCode() == KeyEvent.VK_ENTER)) {
setContentPane(gamePanel);
//add(gamePanel);
}
}
else{
if ((e.getKeyCode() == KeyEvent.VK_ENTER)) {
System.exit(0);
}
}
}
});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(800, 600);
setLocationRelativeTo(null);
setTitle("JavaGame2");
setResizable(false);
}
public static void main(String[] args) {
JFrame jgame = new JavaGame2();
jgame.setVisible(true);
}
}
MenuPanel class extends JPanel
public class MenuPanel extends JPanel implements ActionListener{
public MenuPanel(){
setFocusable(true);
setBackground(Color.BLACK);
setDoubleBuffered(true);
setSize(800,600);
}
public void actionPerformed(ActionEvent e) {
}
}
And here GamePanel class
public class GamePanel extends JPanel implements ActionListener{
public GamePanel (){
addKeyListener(new GameAdapter());
setFocusable(true);
requestFocus();
setBackground(Color.BLACK);
setDoubleBuffered(true);
setSize(800,600);
}
private class GameAdapter extends KeyAdapter{
public void keyReleased(KeyEvent e) {
ship.keyReleased(e);
}
public void keyPressed(KeyEvent e) {
ship.keyPressed(e);
}
}
}
It doesn't work. GamePanel don't want to focus, I tried to do every thing that I read.
I think u will say that JPanel is not focusable component. But when there was one panel it somehow worked.
How can I fix this focus problem?
Maybe u will say that u prefer don't use KeyAdapter, but I think it looks pretty nice in my code.
setFocusable()? or requestFocus()? requestFocusInWindow()? How should I use them? Maybe I have mistake before and this is not my first problem?
Thanks in advance.
And Thanks for editing.

Short answer, use the key bindings API, it allows you to control the level of focus that a component requires before key events are triggered.
Longer answer, the active panel needs to have keyboard focus. You can use requestFocusInWindow, but there is no guarantee that the component will actually receive focus. When to call this is a tricky thing. You could try overriding addNotify of the panels and calling to there, just make sure you call super.addNotify first, weird things happen when you don't
You will also need to consider what will happen if the component loses focus
As a side note:
setDoubleBuffered(true); is irrelevant, as Swing components are double buffered by default. Generally you might disable this if you wanted to print the component. No harm in calling it though
Calling setSize on your components is irrelevant, as you components will be under the control of a layout manager, which will determine the size of the component itself. You'd be better off overriding getPreferredSize and returning an appropriate size for the layout manager
Calling setSize on JFrame is also a bad idea. Frames have borders, this means that your viewable area will be the frame size - the frames border insets, which will be less the 800x600 you've specified. Better to utilise the previous comment and call pack on the JFrame, which will pack the frame around the content so that it meets the contents requirements...
Personally, I would also localise the KeyListener to the actually component itself, this allows the component to act as it's own controller making it more portable...IMHO
Updated with controller idea...
A "really" simplified concept would be to have some kind of "controller" that the menu and game panel could communicate through, for example...
public interface GameController {
public void showMenu();
public void showGame();
}
You would then pass a reference of this interface to the MenuPanel...
public class MenuPanel extends JPanel implements ActionListener{
public MenuPanel(GameController controller){
//...
}
public Dimension getPreferredSize() {
return new Dimension(800, 600);
}
And the GamePanel...
public class GamePanel extends JPanel implements ActionListener{
public GamePanel (GameController controller){
//...
}
public Dimension getPreferredSize() {
return new Dimension(800, 600);
}
You would, obviously, need to construct a implementation of the controller...
public class CardLayoutGameController implements GameController {
public static final String GAME_PANEL = "GamePanel";
public static final String MENU_PANEL = "MenuPanel";
private Container container;
private CardLayout cardLayout;
public CardLayoutGameController(Container parent, CardLayout layout) {
container = parent;
cardLayout = layout;
}
public void showMenu() {
cardLayout.show(container, MENU_PANEL);
}
public void showGame() {
cardLayout.show(container, GAME_PANEL);
}
}
You would then construct your UI around this controller, for example...
public class JavaGame2 extends JFrame {
public JavaGame2(){
CardLayout layout = new CardLayout();
setLayout(layout);
GameController controller = new CardLayoutGameController(getContentPane(), layout);
gamePanel = new GamePanel(controller);
menuPanel = new MenuPanel(controller);
add(gamePanel, CardLayoutGameController.GAME_PANEL);
add(menuPanel, CardLayoutGameController.MENU_PANEL);
controller.showMenu();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocationRelativeTo(null);
setTitle("JavaGame2");
setResizable(false);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame jgame = new JavaGame2();
jgame.setVisible(true);
}
});
}
}
Is this just an "example" to help spark the idea, haven't tested this, just hacked out here so it might blow up :P

use actionlistener to call void function in same class

I have problem to use action listener to call function void in same class.
example..
code:
public class Product extends JPanel {
JButton add;
JPanel pAdd;
JLabel test;
JFrame frame;
public Product() {
add = new JButton("Add Product");
add.addActionListener(new ButtonListener());
add(add);
}
public void panelAdd(){
pAdd = new JPanel();
pAdd.add(new JLabel("try"));
add(pAdd);
}
private class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
panelAdd();
}
}
}
How to make call the panelAdd void method?

When you add components to visible JFrame/JPanel/other components, you neet to call revalidate() andrepaint() methods after adding. Change your panelAdd() like next:
public void panelAdd(){
pAdd = new JPanel();
pAdd.add(new JLabel("try"));
add(pAdd);
revalidate();
repaint();
}

If you put
System.out.println("hi");
to
public void panelAdd(){
System.out.println("hi");
pAdd = new JPanel();
pAdd.add(new JLabel("try"));
add(pAdd);
}
you will see hi printed to your console , your code are working, but you have problem in Layout .

How to setAlwaysOnTop() when clicking on a JButton in Java?

I would like to use setAlwaysOnTop(boolean) in java.
I want to setAlwaysOnTop() when I click on a JButton and this JButton has its own actionListener
My Problem is I don't know how to set the JFrame on top at this situation, because it's not inside the constructor nor there is a method getFrame()
I tried creating a method inside the constructor but it does not work :S.
UPDATE:
private class optionAction implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getSource() == onTop) //onTop is a menuItem when I click it it should make the frame Always on top.
frame.setAlwaysOnTop(true); //This does not work of course just to demonstrat you what I want to do
}
}

The following code lines show you how it can be done with a direct implementation of ActionListener() assigned to a button declared inside the constructor. (You can also do this anywhere else in your class.)
class MyFrame extends JFrame {
public MyFrame() {
// ...
JButton button = new JButton("PRESS");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
setAlwaysOnTop(true);
// Alternatively use MyFrame.this.setAlwaysOnTop(true);
}
});
add(button);
// ...
}
}

An idea might be to pass a reference to your JFrame to the constructor of your implementation of the ActionListener.
Maybe something like this:
class MyActionListener implements ActionListener {
private JFrame jFrame;
public MyActionListener(JFrame jFrame) {
this.jFrame = jframe;
}
public void onClick(Event event) {
jFrame.setAlwaysOnTop(true);
}
}

create a boolean called ontop
boolean ontop = false;
jbutton.addActionListener(new ActionListener()) {
public void actionPerformed(ActionEvent e){
if (ontop) {
frame.setAlwaysOnTop(false);
ontop = false;
}
else {frame.setAlwaysOnTop(true); ontop = true}
});

The correct working code for this question is below:
private class optionAction implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getSource() == onTop) //onTop is a menuItem
setAlwaysOnTop(true); //This does not work of course just to demonstrate you what I want to do
}
}
The reason this is does not work because I was setting the setAlwaysOnTop on a JFrame object, which it doesn't exists in that class.
To set the setALwaysOnTop on a JFrame you have to remove the frame. and just add `setAlwaysOnTop()

Fast Jbutton clicks results in no action

Hey guys, I have a problem with a code that I've been writing.
I have a JFrame that contains two buttons. Each of these buttons has an action. The problem I'm having is with a JButton called "btnDone" that's supposed to get back to a previous screen. If I I keep pushing the button repeatedly, eventually the "btnDone" would stop doing the logic it's supposed to do. My code is as follows:
For the frame:
public class ItemLocatorPnl extends JPnl
{
private static final long serialVersionUID = 1L;
private Pnl pnl;
private JButton btnDone;
private JButton btnRefreshData;
public void setPnl(Pnl pnl) {
this.pnl = pnl;
}
public ItemLocatorPnl(Pnl pnl)
{
super();
this.pnl=pnl;
initialize();
}
private void initialize()
{
this.setSize(300, 200);
JPanel jContentPane = new JPanel();
jContentPane.setLayout(new MigLayout());
// (1) Remove window frame
setUndecorated(true);
// (3) Set background to white
jContentPane.setBackground(Color.white);
// (5) Add components to the JPnl's contentPane
POSLoggers.initLog.writeDebug("ItemLocator: Adding icon");
jContentPane.add(wmIconLabel, "align left");
POSLoggers.initLog.writeDebug("ItemLocator: Adding global controls");
jContentPane.add(createUpperPanel(), "align right, wrap");
POSLoggers.initLog.writeDebug("ItemLocator: Adding main panel");
jContentPane.add(pnl,"width 100%,height 100%, span 3");
// (6) Attach the content pane to the JPnl
this.setContentPane(jContentPane);
}
private JPanel createUpperPanel()
{
JPanel upperPanel=new JPanel();
MigLayout mig = new MigLayout("align right", "", "");
upperPanel.setLayout(mig);
upperPanel.setBackground(Color.WHITE);
// Create the Done button
btnDone= GraphicalUtilities.getPOSButton("<html><center>Done</center></html>");
btnDone.addActionListener(new ButtonListener());
// Create the Refresh Data button
btnRefreshData = GraphicalUtilities.getPOSButton("<html><center>Refresh<br>Data</center></html>");
btnRefreshData.addActionListener(new ButtonListener());
//Addiing buttons to the Panel
upperPanel.add(btnRefreshData, "width 100:170:200, height 100!");
upperPanel.add(btnDone, "width 100:170:200, height 100!");
return upperPanel;
}
public class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
try {
if (e.getSource() == btnRefreshData) {
Actual.refreshData();
} else if (e.getSource() == btnDone) {
Actual.backToMainScreen();
}
}
catch (Exception ex)
{
}
}
}
}
This is the method that the btnDone button calls upon clicking:
public static void backToMainScreen()
{
frame.setVisible(false);
frame.dispose();
}
This is the code that displays the JFrame:
public static void displayItemLocatorFrame()
{
pnl = new Pnl();
frame = new Frame(pnl);
frame.setVisible(true);
pnl.getSearchCriteria().requestFocus();
}
Please note that the "frame" object is static, and all of my methods are static, and they exist in a static class called Actual.
So in short, I just want to make sure that no matter how many times a user clicks on the button, and no matter how fast the clicks were, the frame should act normally.
Any suggestions? (I tried synchronizing my methods with no luck..)

I would generally prefer to use an Action for what you're trying to do.
So your code might look like this:
btnDone = new JButton(new CloseFrameAction());
...
private class CloseFrameAction extends AbstractAction
{
public CloseFrameAction()
{
super("Done");
}
public void actionPerformed(ActionEvent e)
{
frame.dispose();
setEnabled(false);
}
}
Notice the setEnabled(false) line - this should disable the button and prevent the user clicking on it again. Obviously I don't know what your exact requirements are but this is the general approach I would take.

The problem was with using a static panel that was instantiated with the click of the button each time. Removing "static" has finally fixed my problem! Thanks everyone for the help.