Java Swing: do something while a key is pressed

Question

Im using KeyAdpater to get events and addKeyListener method and working fine. The problem is that when a key is pressed, the action is triggered only once, and not when pressed, after 3-4 seconds, holding the key, the action occurs all the time I want.

I would like to know if there is a way to do the action all the time when the key is pressed from the very beginning , and not after 3-4 seconds while holding it down.

I thought of the following solution, but maybe there is an already implemented way:

 public abstract class MyKeyAdapter extends KeyAdapter{ private boolean isPressed = false; private int pressedKey = 0; Thread t = new Thread(new Runnable() { @Override public void run() { while(isPressed) keyPressedAction(pressedKey); } }); @Override public void keyPressed(KeyEvent e) { if(!isPressed){ pressedKey = e.getKeyCode(); t.start(); } } @Override public void keyReleased(KeyEvent e) { if(isPressed && e.getKeyCode()==pressedKey)} isPressed = false; } public abstract void keyPressedAction(int key); } 

Answer 1

I had good success using Key Bindings , not KeyListener, and start the " Swing Timer" when you press a key, and then stop the timer when Swing is released. You can distinguish between keystrokes and releases by passing the correct KeyStroke object to the associated InputMap component using the KeyStroke.getKeyStroke(int keyCode, int modifiers, boolean onKeyRelease) method KeyStroke.getKeyStroke(int keyCode, int modifiers, boolean onKeyRelease) , found here: KeyStroke API . If the boolean parameter is false, the input will respond to a keystroke, and vice versa, if the parameter is true.

For a quick and inelegant example:

 import java.awt.Color; import java.awt.Dimension; import java.awt.Font; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import javax.swing.*; @SuppressWarnings("serial") public class KeyBindingEg extends JPanel { private static final String UP_KEY_PRESSED = "up key pressed"; private static final String UP_KEY_RELEASED = "up key released"; private static final int UP_TIMER_DELAY = 200; private static final Color FLASH_COLOR = Color.red; private Timer upTimer; private JLabel label = new JLabel(); public KeyBindingEg() { label.setFont(label.getFont().deriveFont(Font.BOLD, 32)); label.setOpaque(true); add(label); setPreferredSize(new Dimension(400, 300)); int condition = WHEN_IN_FOCUSED_WINDOW; InputMap inputMap = getInputMap(condition); ActionMap actionMap = getActionMap(); KeyStroke upKeyPressed = KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false); KeyStroke upKeyReleased = KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, true); inputMap.put(upKeyPressed, UP_KEY_PRESSED); inputMap.put(upKeyReleased, UP_KEY_RELEASED); actionMap.put(UP_KEY_PRESSED, new UpAction(false)); actionMap.put(UP_KEY_RELEASED, new UpAction(true)); } private class UpAction extends AbstractAction { private boolean onKeyRelease; public UpAction(boolean onKeyRelease) { this.onKeyRelease = onKeyRelease; } @Override public void actionPerformed(ActionEvent evt) { if (!onKeyRelease) { if (upTimer != null && upTimer.isRunning()) { return; } System.out.println("key pressed"); label.setText(UP_KEY_PRESSED); upTimer = new Timer(UP_TIMER_DELAY, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { Color c = label.getBackground(); if (FLASH_COLOR.equals(c)) { label.setBackground(null); label.setForeground(Color.black); } else { label.setBackground(FLASH_COLOR); label.setForeground(Color.white); } } }); upTimer.start(); } else { System.out.println("Key released"); if (upTimer != null && upTimer.isRunning()) { upTimer.stop(); upTimer = null; } label.setText(""); } } } private static void createAndShowGui() { KeyBindingEg mainPanel = new KeyBindingEg(); JFrame frame = new JFrame("KeyBindingEg"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(mainPanel); frame.pack(); frame.setLocationByPlatform(true); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGui(); } }); } }