How can I change this code to accept any key (not only F5) and print the key?
component.getRootPane().getInputMap(JRootPane.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_F5, 0), "F5 Pressed");
component.getRootPane().getActionMap().put("F5 Pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
// Code here
}
});
how can I ("cahnhe") this code to accept any key (not only F5) and print
the key?
sorry this question doesn't make me some sence, in this form
basic is described in tutorial,
component.getRootPane() could be valid only for JFrame, JDialog, JWindow, practically only JFrame has accesible RootPane
otherwise to add Input/ActionMap to the desired JComponent directly
Use KeyboardFocusManager to register a KeyEventDispatcher:
KeboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher() {
#Override
public boolean dispatchKeyEvent(KeyEvent ke) {
if (yourComponent.hasFocus && ke.getID == KeyEvent.KEY_TYPED) {
// Your code here
// Use ke.getKeyChar() to detect which key was pressed.
}
}
}
Related
I'm trying to implement a KeyListener for my JFrame. On the constructor, I'm using this code:
System.out.println("test");
addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent e) { System.out.println( "tester"); }
public void keyReleased(KeyEvent e) { System.out.println("2test2"); }
public void keyTyped(KeyEvent e) { System.out.println("3test3"); }
});
When I run it, the test message comes up in my console. However, when I press a key, I don't get any of the other messages, as if the KeyListener was not even there.
I was thinking that it could be because the focus is not on the JFrame
and so they KeyListener doesn't receive any events. But, I'm pretty sure it is.
Is there something that I am missing?
If you don't want to register a listener on every component,
you could add your own KeyEventDispatcher to the KeyboardFocusManager:
public class MyFrame extends JFrame {
private class MyDispatcher implements KeyEventDispatcher {
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
if (e.getID() == KeyEvent.KEY_PRESSED) {
System.out.println("tester");
} else if (e.getID() == KeyEvent.KEY_RELEASED) {
System.out.println("2test2");
} else if (e.getID() == KeyEvent.KEY_TYPED) {
System.out.println("3test3");
}
return false;
}
}
public MyFrame() {
add(new JTextField());
System.out.println("test");
KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher(new MyDispatcher());
}
public static void main(String[] args) {
MyFrame f = new MyFrame();
f.pack();
f.setVisible(true);
}
}
You must add your keyListener to every component that you need. Only the component with the focus will send these events. For instance, if you have only one TextBox in your JFrame, that TextBox has the focus. So you must add a KeyListener to this component as well.
The process is the same:
myComponent.addKeyListener(new KeyListener ...);
Note: Some components aren't focusable like JLabel.
For setting them to focusable you need to:
myComponent.setFocusable(true);
InputMaps and ActionMaps were designed to capture the key events for the component, it and all of its sub-components, or the entire window. This is controlled through the parameter in JComponent.getInputMap(). See How to Use Key Bindings for documentation.
The beauty of this design is that one can pick and choose which key strokes are important to monitor and have different actions fired based on those key strokes.
This code will call dispose() on a JFrame when the escape key is hit anywhere in the window. JFrame doesn't derive from JComponent so you have to use another component in the JFrame to create the key binding. The content pane might be such a component.
InputMap inputMap;
ActionMap actionMap;
AbstractAction action;
JComponent component;
inputMap = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
actionMap = component.getActionMap();
action = new AbstractAction()
{
#Override
public void actionPerformed(ActionEvent e)
{
dispose();
}
};
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), "dispose");
actionMap.put("dispose", action);
I got the same problem until i read that the real problem is about FOCUS the your JFrame has already added Listeners but tour frame is never on Focus because you got a lot of components inside your JFrame that also are focusable so try:
JFrame.setFocusable(true);
Good Luck
KeyListener is low level and applies only to a single component. Despite attempts to make it more usable JFrame creates a number of component components, the most obvious being the content pane. JComboBox UI is also often implemented in a similar manner.
It's worth noting the mouse events work in a strange way slightly different to key events.
For details on what you should do, see my answer on Application wide keyboard shortcut - Java Swing.
Deion (and anyone else asking a similar question), you could use Peter's code above but instead of printing to standard output, you test for the key code PRESSED, RELEASED, or TYPED.
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
if (e.getID() == KeyEvent.KEY_PRESSED) {
if (e.getKeyCode() == KeyEvent.VK_F4) {
dispose();
}
} else if (e.getID() == KeyEvent.KEY_RELEASED) {
if (e.getKeyCode() == KeyEvent.VK_F4) {
dispose();
}
} else if (e.getID() == KeyEvent.KEY_TYPED) {
if (e.getKeyCode() == KeyEvent.VK_F4) {
dispose();
}
}
return false;
}
in order to capture key events of ALL text fields in a JFrame,
one can employ a key event post processor.
Here is a working example, after you add the obvious includes.
public class KeyListenerF1Demo extends JFrame implements KeyEventPostProcessor {
public static final long serialVersionUID = 1L;
public KeyListenerF1Demo() {
setTitle(getClass().getName());
// Define two labels and two text fields all in a row.
setLayout(new FlowLayout());
JLabel label1 = new JLabel("Text1");
label1.setName("Label1");
add(label1);
JTextField text1 = new JTextField(10);
text1.setName("Text1");
add(text1);
JLabel label2 = new JLabel("Text2");
label2.setName("Label2");
add(label2);
JTextField text2 = new JTextField(10);
text2.setName("Text2");
add(text2);
// Register a key event post processor.
KeyboardFocusManager.getCurrentKeyboardFocusManager()
.addKeyEventPostProcessor(this);
}
public static void main(String[] args) {
JFrame f = new KeyListenerF1Demo();
f.setName("MyFrame");
f.pack();
f.setVisible(true);
}
#Override
public boolean postProcessKeyEvent(KeyEvent ke) {
// Check for function key F1 pressed.
if (ke.getID() == KeyEvent.KEY_PRESSED
&& ke.getKeyCode() == KeyEvent.VK_F1) {
// Get top level ancestor of focused element.
Component c = ke.getComponent();
while (null != c.getParent())
c = c.getParent();
// Output some help.
System.out.println("Help for " + c.getName() + "."
+ ke.getComponent().getName());
// Tell keyboard focus manager that event has been fully handled.
return true;
}
// Let keyboard focus manager handle the event further.
return false;
}
}
This should help
yourJFrame.setFocusable(true);
yourJFrame.addKeyListener(new java.awt.event.KeyAdapter() {
#Override
public void keyTyped(KeyEvent e) {
System.out.println("you typed a key");
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println("you pressed a key");
}
#Override
public void keyReleased(KeyEvent e) {
System.out.println("you released a key");
}
});
Hmm.. what class is your constructor for? Probably some class extending JFrame? The window focus should be at the window, of course but I don't think that's the problem.
I expanded your code, tried to run it and it worked - the key presses resulted as print output. (run with Ubuntu through Eclipse):
public class MyFrame extends JFrame {
public MyFrame() {
System.out.println("test");
addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent e) {
System.out.println("tester");
}
public void keyReleased(KeyEvent e) {
System.out.println("2test2");
}
public void keyTyped(KeyEvent e) {
System.out.println("3test3");
}
});
}
public static void main(String[] args) {
MyFrame f = new MyFrame();
f.pack();
f.setVisible(true);
}
}
I have been having the same problem. I followed Bruno's advice to you and found that adding a KeyListener just to the "first" button in the JFrame (ie, on the top left) did the trick. But I agree with you it is kind of an unsettling solution. So I fiddled around and discovered a neater way to fix it. Just add the line
myChildOfJFrame.requestFocusInWindow();
to your main method, after you've created your instance of your subclass of JFrame and set it visible.
lol .... all you have to do is make sure that
addKeyListener(this);
is placed correctly in your code.
You could have custom JComponents set their parent JFrame focusable.
Just add a constructor and pass in the JFrame. Then make a call to setFocusable() in paintComponent.
This way the JFrame will always receive KeyEvents regardless of whether other components are pressed.
I'm currently working on a little game. I'm using getKeyCode to move my character but the thing is that I don't want you to be able to keep moving if you hold in the button. Is there anyway I can use getKeyCode to only register on the first click and then won't register until I release the button and press again?
else if (event.getKeyCode()== KeyEvent.VK_UP)
{
spelare1.setLocation(spelare1.getX(),spelare1.getY()-50);
}
This is how it currently looks like.
I think you are confusing KeyEvents. VK_UP is the up arrow key. Use KeyEvent.KEY_RELEASED to react on a released key.
You can keep a boolean indicating whether the key is currently pressed. Then you can react once after each press, like in this example:
public static void main(String[] args) {
JFrame f = new JFrame();
f.addKeyListener(new KeyAdapter() {
private boolean pressed;
#Override
public void keyReleased(KeyEvent e) {
pressed = false;
}
#Override
public void keyPressed(KeyEvent e) {
if (!pressed) {
System.out.println("Key pressed: " + e.getKeyCode());
pressed = true;
}
}
});
SwingUtilities.invokeLater(new Runnable() {
public void run() {
f.setVisible(true);
}
});
}
Depending on your needs, you might want to have a separate state for each key, or just one shared state.
I have a program which produces a JFrame and then a JPanel on top of it. For the program, I have tried implementing the KeyListener and then adding the methods (for both components), but the program does not pick any of my key strokes up. What am I doing wrong?
EDIT
This is my code. It is a part of the class which creates the JFrame. It still does not pick up the press of the ESC key.
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
int keyCode = e.getKeyCode();
if(keyCode == KeyEvent.VK_ESCAPE){
System.out.println("Hi");
}else{
System.out.println("Hello");
}
}
#Override
public void keyReleased(KeyEvent e) {
}
Without your code, all I can tell you is that usually when people ask this they don't know that the interface KeyListener contain three methods as Agusti-N states in their answer here:
void keyTyped(KeyEvent)
void keyPressed(KeyEvent)
void keyReleased(KeyEvent)
If you use keyTyped and you are using event.getKeyCode() to check for the character entered, this will not work. You should use getKeyChar() for keyTyped and getKeyCode() for keyPressed and keyReleased. Otherwise you'll get null.
You should only use this if you do not have any other alternative, in most cases you want to use Key Bindings.
I'm trying to implement a KeyListener for my JFrame. On the constructor, I'm using this code:
System.out.println("test");
addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent e) { System.out.println( "tester"); }
public void keyReleased(KeyEvent e) { System.out.println("2test2"); }
public void keyTyped(KeyEvent e) { System.out.println("3test3"); }
});
When I run it, the test message comes up in my console. However, when I press a key, I don't get any of the other messages, as if the KeyListener was not even there.
I was thinking that it could be because the focus is not on the JFrame
and so they KeyListener doesn't receive any events. But, I'm pretty sure it is.
Is there something that I am missing?
If you don't want to register a listener on every component,
you could add your own KeyEventDispatcher to the KeyboardFocusManager:
public class MyFrame extends JFrame {
private class MyDispatcher implements KeyEventDispatcher {
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
if (e.getID() == KeyEvent.KEY_PRESSED) {
System.out.println("tester");
} else if (e.getID() == KeyEvent.KEY_RELEASED) {
System.out.println("2test2");
} else if (e.getID() == KeyEvent.KEY_TYPED) {
System.out.println("3test3");
}
return false;
}
}
public MyFrame() {
add(new JTextField());
System.out.println("test");
KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher(new MyDispatcher());
}
public static void main(String[] args) {
MyFrame f = new MyFrame();
f.pack();
f.setVisible(true);
}
}
You must add your keyListener to every component that you need. Only the component with the focus will send these events. For instance, if you have only one TextBox in your JFrame, that TextBox has the focus. So you must add a KeyListener to this component as well.
The process is the same:
myComponent.addKeyListener(new KeyListener ...);
Note: Some components aren't focusable like JLabel.
For setting them to focusable you need to:
myComponent.setFocusable(true);
InputMaps and ActionMaps were designed to capture the key events for the component, it and all of its sub-components, or the entire window. This is controlled through the parameter in JComponent.getInputMap(). See How to Use Key Bindings for documentation.
The beauty of this design is that one can pick and choose which key strokes are important to monitor and have different actions fired based on those key strokes.
This code will call dispose() on a JFrame when the escape key is hit anywhere in the window. JFrame doesn't derive from JComponent so you have to use another component in the JFrame to create the key binding. The content pane might be such a component.
InputMap inputMap;
ActionMap actionMap;
AbstractAction action;
JComponent component;
inputMap = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
actionMap = component.getActionMap();
action = new AbstractAction()
{
#Override
public void actionPerformed(ActionEvent e)
{
dispose();
}
};
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), "dispose");
actionMap.put("dispose", action);
I got the same problem until i read that the real problem is about FOCUS the your JFrame has already added Listeners but tour frame is never on Focus because you got a lot of components inside your JFrame that also are focusable so try:
JFrame.setFocusable(true);
Good Luck
KeyListener is low level and applies only to a single component. Despite attempts to make it more usable JFrame creates a number of component components, the most obvious being the content pane. JComboBox UI is also often implemented in a similar manner.
It's worth noting the mouse events work in a strange way slightly different to key events.
For details on what you should do, see my answer on Application wide keyboard shortcut - Java Swing.
Deion (and anyone else asking a similar question), you could use Peter's code above but instead of printing to standard output, you test for the key code PRESSED, RELEASED, or TYPED.
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
if (e.getID() == KeyEvent.KEY_PRESSED) {
if (e.getKeyCode() == KeyEvent.VK_F4) {
dispose();
}
} else if (e.getID() == KeyEvent.KEY_RELEASED) {
if (e.getKeyCode() == KeyEvent.VK_F4) {
dispose();
}
} else if (e.getID() == KeyEvent.KEY_TYPED) {
if (e.getKeyCode() == KeyEvent.VK_F4) {
dispose();
}
}
return false;
}
in order to capture key events of ALL text fields in a JFrame,
one can employ a key event post processor.
Here is a working example, after you add the obvious includes.
public class KeyListenerF1Demo extends JFrame implements KeyEventPostProcessor {
public static final long serialVersionUID = 1L;
public KeyListenerF1Demo() {
setTitle(getClass().getName());
// Define two labels and two text fields all in a row.
setLayout(new FlowLayout());
JLabel label1 = new JLabel("Text1");
label1.setName("Label1");
add(label1);
JTextField text1 = new JTextField(10);
text1.setName("Text1");
add(text1);
JLabel label2 = new JLabel("Text2");
label2.setName("Label2");
add(label2);
JTextField text2 = new JTextField(10);
text2.setName("Text2");
add(text2);
// Register a key event post processor.
KeyboardFocusManager.getCurrentKeyboardFocusManager()
.addKeyEventPostProcessor(this);
}
public static void main(String[] args) {
JFrame f = new KeyListenerF1Demo();
f.setName("MyFrame");
f.pack();
f.setVisible(true);
}
#Override
public boolean postProcessKeyEvent(KeyEvent ke) {
// Check for function key F1 pressed.
if (ke.getID() == KeyEvent.KEY_PRESSED
&& ke.getKeyCode() == KeyEvent.VK_F1) {
// Get top level ancestor of focused element.
Component c = ke.getComponent();
while (null != c.getParent())
c = c.getParent();
// Output some help.
System.out.println("Help for " + c.getName() + "."
+ ke.getComponent().getName());
// Tell keyboard focus manager that event has been fully handled.
return true;
}
// Let keyboard focus manager handle the event further.
return false;
}
}
This should help
yourJFrame.setFocusable(true);
yourJFrame.addKeyListener(new java.awt.event.KeyAdapter() {
#Override
public void keyTyped(KeyEvent e) {
System.out.println("you typed a key");
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println("you pressed a key");
}
#Override
public void keyReleased(KeyEvent e) {
System.out.println("you released a key");
}
});
Hmm.. what class is your constructor for? Probably some class extending JFrame? The window focus should be at the window, of course but I don't think that's the problem.
I expanded your code, tried to run it and it worked - the key presses resulted as print output. (run with Ubuntu through Eclipse):
public class MyFrame extends JFrame {
public MyFrame() {
System.out.println("test");
addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent e) {
System.out.println("tester");
}
public void keyReleased(KeyEvent e) {
System.out.println("2test2");
}
public void keyTyped(KeyEvent e) {
System.out.println("3test3");
}
});
}
public static void main(String[] args) {
MyFrame f = new MyFrame();
f.pack();
f.setVisible(true);
}
}
I have been having the same problem. I followed Bruno's advice to you and found that adding a KeyListener just to the "first" button in the JFrame (ie, on the top left) did the trick. But I agree with you it is kind of an unsettling solution. So I fiddled around and discovered a neater way to fix it. Just add the line
myChildOfJFrame.requestFocusInWindow();
to your main method, after you've created your instance of your subclass of JFrame and set it visible.
lol .... all you have to do is make sure that
addKeyListener(this);
is placed correctly in your code.
You could have custom JComponents set their parent JFrame focusable.
Just add a constructor and pass in the JFrame. Then make a call to setFocusable() in paintComponent.
This way the JFrame will always receive KeyEvents regardless of whether other components are pressed.
I would like to create an application wide keyboard shortcut for a Java Swing application.
Looping over all components and adding the shortcut on each, has focus related side effects, and seems like a brute force solution.
Anyone has a cleaner solution?
For each window, use JComponent.registerKeyboardAction with a condition of WHEN_IN_FOCUSED_WINDOW. Alternatively use:
JComponent.getInputMap(WHEN_IN_FOCUSED_WINDOW).put(keyStroke, command);
JComponent.getActionMap().put(command,action);
as described in the registerKeyboardAction API docs.
Install a custom KeyEventDispatcher. The KeyboardFocusManager class is also a good place for this functionality.
KeyEventDispatcher
For people wondering (like me) how to use KeyEventDispatcher, here is an example that I put together. It uses a HashMap for storing all global actions, because I don't like large if (key == ..) then .. else if (key == ..) then .. else if (key ==..) .. constructs.
/** map containing all global actions */
private HashMap<KeyStroke, Action> actionMap = new HashMap<KeyStroke, Action>();
/** call this somewhere in your GUI construction */
private void setup() {
KeyStroke key1 = KeyStroke.getKeyStroke(KeyEvent.VK_A, KeyEvent.CTRL_DOWN_MASK);
actionMap.put(key1, new AbstractAction("action1") {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Ctrl-A pressed: " + e);
}
});
// add more actions..
KeyboardFocusManager kfm = KeyboardFocusManager.getCurrentKeyboardFocusManager();
kfm.addKeyEventDispatcher( new KeyEventDispatcher() {
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
KeyStroke keyStroke = KeyStroke.getKeyStrokeForEvent(e);
if ( actionMap.containsKey(keyStroke) ) {
final Action a = actionMap.get(keyStroke);
final ActionEvent ae = new ActionEvent(e.getSource(), e.getID(), null );
SwingUtilities.invokeLater( new Runnable() {
#Override
public void run() {
a.actionPerformed(ae);
}
} );
return true;
}
return false;
}
});
}
The use of SwingUtils.invokeLater() is maybe not necessary, but it is probably a good idea not to block the global event loop.
When you have a menu, you can add global keyboard shortcuts to menu items:
JMenuItem item = new JMenuItem(action);
KeyStroke key = KeyStroke.getKeyStroke(
KeyEvent.VK_R, KeyEvent.CTRL_DOWN_MASK);
item.setAccelerator(key);
menu.add(item);
A little simplified example:
import java.awt.KeyboardFocusManager;
import java.awt.KeyEventDispatcher;
import java.awt.event.KeyEvent;
KeyboardFocusManager keyManager;
keyManager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
keyManager.addKeyEventDispatcher(new KeyEventDispatcher() {
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
if (e.getID() == KeyEvent.KEY_PRESSED && e.getKeyCode() == 27) {
System.out.println("Esc");
return true;
}
return false;
}
});
Use the following piece of code
ActionListener a=new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
// your code
}
};
getRootPane().registerKeyboardAction(a,KeyStroke.getKeyStroke("ctrl D"),JComponent.WHEN_IN_FOCUSED_WINDOW);
Replace "ctrl D" with the shortcut you want.