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KeyListener does not work when exported as a runnable jar file [duplicate]

I am trying to do something when one of the arrow keys are pressed using the KeyListener in my JPanel class. Here is my code:
public class TestPanel extends JPanel implements KeyListener{
public TestPanel(){
this.addKeyListener(this);
this.setFocusable(true);
this.requestFocusInWindow();
}
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left");
}
}
public void keyTyped(KeyEvent e) {}
public void keyReleased(KeyEvent e) {}
}
My main method adds a new instance of this panel to a frame and displays it. Do I need to add the keylistener to the JFrame? In my case, this would be difficult and inefficient, so I would like to make it work with this JPanel if possible. Anyone know what I am doing wrong?
EDIT: Key Bindings code that does not work either:
public class GamePanel extends JPanel implements ActionListener{
//Constructor
public GamePanel(){
setupKeyBinding();
this.setFocusable(true);
this.requestFocusInWindow();
}
private void setupKeyBinding() {
int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
InputMap inMap = getInputMap(condition);
ActionMap actMap = getActionMap();
inMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "Left");
actMap.put("Left", new leftAction());
}
private class leftAction extends AbstractAction {
public void actionPerformed(ActionEvent e) {
System.out.println("test");
}
}
public void actionPerformed(ActionEvent e) {
//some other game info
}
}
Can someone tell me why this doesnt work either? (my second action listener is for other stuff needed for my game)

If you search this problem, you'll see that it is asked and has been solved many times.
KeyListeners need to be on the focused component to work. One solution is to give your component the focus after first making it focusable.
Better by a long shot however is to use Key Bindings. Google the tutorial on this.
Please have a look at my answer to this question for more on this, including many of the gory details.

For reference, I've create an example using your approach; while it works, it also suggests a focus problem elsewhere in your code. Key Bindings avoid this, as shown here.
Addendum: Here's my working key binding.
private static class TestPanel extends JPanel {
private static final String LEFT = "Left";
private Action left = new AbstractAction(LEFT) {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(LEFT);
}
};
private static final String RIGHT = "Right";
private Action right = new AbstractAction(RIGHT) {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(RIGHT);
}
};
public TestPanel() {
this.getInputMap().put(
KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), LEFT);
this.getActionMap().put(LEFT, left);
this.getInputMap().put(
KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), RIGHT);
this.getActionMap().put(RIGHT, right);
}
}
Original SSCCE:
import java.awt.EventQueue;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* #see https://stackoverflow.com/a/16531380/230513
*/
public class Test {
private void display() {
JFrame f = new JFrame("Test");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new TestPanel());
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private static class TestPanel extends JPanel implements KeyListener {
public TestPanel() {
this.addKeyListener(this);
this.setFocusable(true);
this.requestFocusInWindow();
}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left");
}
}
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Test().display();
}
});
}
}

For receives key events on JPanel you must set focus:
setFocusable(true);
requestFocus();
the JPanel now has focus, so it receives key events

I had to do two things: I added comp.setFocusable(true); to the component comp that listens to key events, and I added comp.requestFocus(); to each action which caused comp to lose the focus.

Listening for the CAPS key [duplicate]

This question already has answers here:
KeyListener after Button Is Pressed
(2 answers)
Closed 6 years ago.
I have been trying to build a small utility that listens for when the user presses the "Caps Lock" key. The program should start and first display wheter the key is ON or OFF. The program should also listen for any changes, and update the frame accordingly.
Unfortunately, the only part I can get right is in the beginning, when the frame displays if the Caps key is on or off. After that, it gets stuck. Even if I press the key it changes nothing on screen.
The program is also supposed to produce a .beep() sound when the caps key is on, but it only works if I start it with the key on.
Code:
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(400, 400);
JLabel label = new JLabel("CAPS LOCK IS ON!");
JLabel label1 = new JLabel("CAPS LOCK IS OFF!");
boolean check = Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK);
if (check == true) {
frame.repaint();
frame.add(label);
Toolkit.getDefaultToolkit().beep();
} else {
frame.repaint();
frame.add(label1);
}
keyPressed(KeyCode.CAPS);
frame.show();
}
public static void keyPressed(KeyCode e) {
boolean check = Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK);
if (check == true) {
Toolkit.getDefaultToolkit().beep();
}
}
EDIT: If you only want to know if the Caps key is toggled(on):
if (Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK)) {
label.setText("CAPS LOCK IS ON!");
Toolkit.getDefaultToolkit().beep();
} else {
label.setText("CAPS LOCK IS OFF");
}
This way it only beeps when the caps key is toggled and doesnt beep when is not toggled.

If you want to track "Caps Lock" only within your application, you can do something like:
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher()
{
#Override
public boolean dispatchKeyEvent(KeyEvent e)
{
if (KeyEvent.VK_CAPS_LOCK == e.getKeyCode())
{
boolean check = Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK);
// do something here
}
return false;
}
});
You also might need to track focus and update state when your app is re-focused.
However if you want your application to track Caps Lock system-wide as I suspect you do, than unfortunately you are out of luck. There is no way in pure Java to do it as this is a very OS-specific feature. Still for Windows there is a wrapper around C-code https://github.com/kristian/system-hook

As mentioned in other answers, your code isn't registering a KeyListener, so it's simply reading the locking state of the key once.
To capture the state change on CapsLock, You need to watch for the keyPressed (cap lock on) and keyReleased (cap lock off) separately.
Take a look at this example:
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class CapChecker {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel label = new JLabel();
frame.add(label);
frame.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_CAPS_LOCK && Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK)) {
label.setText("CAPS LOCK IS ON!");
Toolkit.getDefaultToolkit().beep();
} else {
label.setText("" + e.getKeyChar());
}
}
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_CAPS_LOCK) {
label.setText("CAPS LOCK IS OFF!");
}
}
});
frame.setVisible(true);
}
});
}
}

After the Frame is shown, your program does nothing. You have to register a KeyListener to the frame:
frame.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {}
public void keyReleased(KeyEvent e) {}
})
In these methods you can react to key presses or releases.

How to use KeyListener

I am currently trying to implement a keylistener in my program so that it does an action when I pressed an arrow key, the object in my program either moves left or right.
Here is the moving method in my program
public void moveDirection(KeyEvent e)
{
int move = 0;
int r = K.getRow();
int c = K.getCol();
if (e.getKeyCode() == 39) move = 1; //KeyEvent.VK_RIGHT
if (e.getKeyCode() == 37) move = 2; //KeyEvent.VK_LEFT
//if (e.getKeyCode() == KeyEvent.VK_DOWN) move = 3;
switch (move)
{
case 1: if (inBound(r, c+1))
K.setLocation(r ,c+1);
if (inBound(r, c-1) && frame2[r][c-1] == K)
frame2[K.getRow()][K.getCol()-1] = null;
break; //move right 39
case 2: K.setLocation(K.getRow(), K.getCol()-1); break; //move left 37
//case 3: b.setLocation(b.getRow()+1, b.getCol()); break; //move down
default: return;
}
processBlockList();
}
I am wondering how the program is supposed to read in (KeyEvent) e. I cannot really type in an arrowkey....
Please help!
edit: I also need to know what I need to add to my code so that my program waits about 700 milliseconds for a keyinput before moving on to another method

http://docs.oracle.com/javase/tutorial/uiswing/events/keylistener.html
Check this tutorial
If it's a UI based application , then " I also need to know what I need to add to my code so that my program waits about 700 milliseconds for a keyinput before moving on to another method" you can use GlassPane or Timer class to fulfill the requirement.
For key Event:
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_LEFT) {
dx = -1;
}
if (key == KeyEvent.VK_RIGHT) {
dx = 1;
}
if (key == KeyEvent.VK_UP) {
dy = -1;
}
if (key == KeyEvent.VK_DOWN) {
dy = 1;
}
}
check this game example http://zetcode.com/tutorials/javagamestutorial/movingsprites/

Here is an SSCCE,
package experiment;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class KeyListenerTester extends JFrame implements KeyListener {
JLabel label;
public KeyListenerTester(String s) {
super(s);
JPanel p = new JPanel();
label = new JLabel("Key Listener!");
p.add(label);
add(p);
addKeyListener(this);
setSize(200, 100);
setVisible(true);
}
#Override
public void keyTyped(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right key typed");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left key typed");
}
}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right key pressed");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left key pressed");
}
}
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right key Released");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left key Released");
}
}
public static void main(String[] args) {
new KeyListenerTester("Key Listener Tester");
}
}
Additionally read upon these links : How to Write a Key Listener and How to Use Key Bindings

The class which implements KeyListener interface becomes our custom key event listener. This listener can not directly listen the key events. It can only listen the key events through intermediate objects such as JFrame. So
Make one Key listener class as
class MyListener implements KeyListener{
// override all the methods of KeyListener interface.
}
Now our class MyKeyListener is ready to listen the key events. But it can not directly do so.
Create any object like JFrame object through which MyListener can listen the key events. for that you need to add MyListener object to the JFrame object.
JFrame f=new JFrame();
f.addKeyListener(new MyKeyListener);

In addition to using KeyListener (as shown by others' answers), sometimes you have to ensure that the JComponent you are using is Focusable. This can be set by adding this to your component(if you are subclassing):
#Override
public void setFocusable(boolean b) {
super.setFocusable(b);
}
And by adding this to your constructor:
setFocusable(true);
Or, if you are calling the function from a parent class/container:
JComponent childComponent = new JComponent();
childComponent.setFocusable(true);
And then doing all the KeyListener stuff mentioned by others.

Java Applet - Moving a ball over the screen

Ok, how to i move from keyboard a ball using an Applet?
I have so far this code, that don't do anything.
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class KeyboardGame extends Applet implements KeyListener
{
private static final long serialVersionUID = 1L;
private static boolean keyboadrRightPressed = false;
public void init()
{
addKeyListener(this);
}
public void keyPressed(KeyEvent e)
{
int keyCode = e.getKeyCode();
if(keyCode == KeyEvent.VK_RIGHT)
{
keyboadrRightPressed = true;
}
else
{
keyboadrRightPressed = false;
}
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
}
public void paint(Graphics g)
{
g.fillOval(20,20,20,20);
g.drawString("String :"+keyboadrRightPressed,20,30);
}
}
And also i have to understand how it works. I don't get why my action listener won't work, do i need an
while(true)
or an Thread?

Your action listener might actually be working fine, but you need to repaint the applet when the key is pressed so that your string actually appears. Try changing the keyPressed to this:
public void keyPressed(KeyEvent e)
{
int keyCode = e.getKeyCode();
if(keyCode == KeyEvent.VK_RIGHT)
{
keyboadrRightPressed = true;
}
else
{
keyboadrRightPressed = false;
}
repaint();
}
Actually moving the ball will differ depending on how you want the ball to actually move. I'm guessing you want it to continue moving right while the key is held down, so what I would do is implement a timer or some other form of thread that every .25 seconds (or however long you want) checks the keyboardRightPressed and will move the ball right if it is true. Then in the keyReleased portion of your code you should also add logic to set keyboardRightPressed back to false when you let up on the key.

repaint() not called when running app from Eclipse?

I never get "paint" written to my command line window when I use Eclipse and Run->cmd to run the program. It works fine if I run System.out.print() from paintComponent in another program. Someone who can help?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUI extends JPanel implements KeyListener, ActionListener
{
private static final long serialVersionUID = 1L;
JFrame frmMain = new JFrame("Kodning");
JTextField text = new JTextField();
JPanel pan = new JPanel();
static char bokstav;
static int x=10, y=80;
boolean convert = false;
String s;
Timer t = new Timer(10, this);
public static void main(String[] args)
{
#SuppressWarnings("unused")
GUI g = new GUI();
}
public GUI()
{
frmMain.setSize(600, 120);
frmMain.setLayout(new GridLayout(2, 1));
frmMain.addWindowListener(hornStang());
frmMain.add(text);
frmMain.add(pan);
frmMain.setFocusable(true);
frmMain.setVisible(true);
frmMain.addKeyListener(this);
text.addKeyListener(this);
pan.addKeyListener(this);
t.start();
}
private static WindowAdapter hornStang()
{
return new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
};
}
public void keyPressed(KeyEvent e)
{
if(e.getKeyCode()== KeyEvent.VK_ENTER)
{
System.out.println("dechifrera");
repaint();
deshiffrera(text.getText());
}
}
public void keyReleased(KeyEvent arg0){}
public void keyTyped(KeyEvent arg0){}
public void deshiffrera(String s)
{
s = this.s;
repaint();
}
#override
public void paintComponent(Graphics g)
{
System.out.println("paint");
for(int i=0;i<s.length();i++)
{
bokstav = s.charAt(i);
switch (bokstav)
{
case 'a':nere(g); hoger(g); prick(g, 0); break;
//en massa case
default:break;
}
x=x+12;
}
}
#Override
public void actionPerformed(ActionEvent e)
{
repaint();
}
}

The component must be added to a visible window/frame/component for it's paintComponent to be called.
GUI is only added as a KeyListener but is neither added to the JFrame, nor any other visible component in the code above. There is no reason for calling paintComponent since the component is not being displayed at all.

There are a number of issues with your code:
Your GUI panel is not in the frame (shouldn't it be added instead of pan?)
String s is uninitialized, which causes a NullPointerException
paint should be overridden instead of paintComponents
paint should not change the state of the component, because it can be called any time.
etc...

You probably miss the output of "System.out.println("paint");" ?
GUI-Apps under Windows cant write to the console (they dont have a console, because it would suck if every GUI-App would also open a black window).
There are two java-interpreters under windows: "javaw.exe" which is a GUI-App and silently discards any System.out-writes. And "java.exe" which is a console-app and allows writing to the console. Try to start your program with "java.exe"

I use this with AWT (not 100% sure whether it's working in Swing too...)
Graphics g = _yourcomponent_.getGraphics();
if (g != null) {
_yourcomponent_.paint(g);
// below the estimated code for Swing:
_yourcomponent_.paintComponent(g);
}