Capturing keystrokes in a panel in java

Question

I want to capture keystrokes when you focus on a panel in java. What should I do?

I use Netbeans as an IDE. I tried to add a keyTyped event, but it does not work.

Here is my code

import com.lanadmin.Interface.ClientInterface; import java.awt.Toolkit; import java.awt.event.InputEvent; import java.awt.event.MouseEvent; import java.rmi.Naming; import java.util.logging.Level; public class RemoteViewer extends javax.swing.JInternalFrame { public RemoteViewer() { initComponents(); rdpanel.setFocusable(true); } @SuppressWarnings("unchecked") // <editor-fold defaultstate="collapsed" desc="Generated Code"> private void initComponents() { rdpanel = new javax.swing.JPanel(); setFocusable(true); rdpanel.setToolTipText("Remote Desktop"); rdpanel.addMouseListener(new java.awt.event.MouseAdapter() { public void mouseClicked(java.awt.event.MouseEvent evt) { rdpanelMouseClicked(evt); } public void mousePressed(java.awt.event.MouseEvent evt) { rdpanelMousePressed(evt); } public void mouseReleased(java.awt.event.MouseEvent evt) { rdpanelMouseReleased(evt); } }); rdpanel.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() { public void mouseMoved(java.awt.event.MouseEvent evt) { rdpanelMouseMoved(evt); } }); rdpanel.addFocusListener(new java.awt.event.FocusAdapter() { public void focusGained(java.awt.event.FocusEvent evt) { rdpanelFocusGained(evt); } }); rdpanel.addKeyListener(new java.awt.event.KeyAdapter() { public void keyPressed(java.awt.event.KeyEvent evt) { rdpanelKeyPressed(evt); } public void keyReleased(java.awt.event.KeyEvent evt) { rdpanelKeyReleased(evt); } public void keyTyped(java.awt.event.KeyEvent evt) { rdpanelKeyTyped(evt); } }); javax.swing.GroupLayout rdpanelLayout = new javax.swing.GroupLayout(rdpanel); rdpanel.setLayout(rdpanelLayout); rdpanelLayout.setHorizontalGroup( rdpanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 679, Short.MAX_VALUE) ); rdpanelLayout.setVerticalGroup( rdpanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 626, Short.MAX_VALUE) ); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addContainerGap() .addComponent(rdpanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) .addContainerGap()) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addContainerGap() .addComponent(rdpanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) .addContainerGap()) ); pack(); }// </editor-fold> private void rdpanelMouseMoved(java.awt.event.MouseEvent evt) { double xScale = Toolkit.getDefaultToolkit().getScreenSize().getWidth() / rdpanel.getWidth(); double yScale = Toolkit.getDefaultToolkit().getScreenSize().getHeight() / rdpanel.getHeight(); try { String current = Login.handler.currentClientAddress.getHostAddress(); ClientInterface client = (ClientInterface) Naming.lookup("rmi://" + current + "/lan"); client.mousemove((int) (evt.getX() * xScale), (int) (evt.getY() * yScale)); } catch (Exception ex) { Log2File.logger.log(Level.SEVERE, null, ex); Log2File.fileHandler.flush(); } } private void rdpanelKeyPressed(java.awt.event.KeyEvent evt) { System.out.println("keypressed"); } private void rdpanelKeyTyped(java.awt.event.KeyEvent evt) { System.out.println("aaa"); } private void rdpanelKeyReleased(java.awt.event.KeyEvent evt) { System.out.println("keyreleased"); } private void rdpanelFocusGained(java.awt.event.FocusEvent evt) { rdpanel.addKeyListener(new java.awt.event.KeyAdapter() { @Override public void keyPressed(java.awt.event.KeyEvent evt) { rdpanelKeyPressed(evt); } @Override public void keyReleased(java.awt.event.KeyEvent evt) { rdpanelKeyReleased(evt); } @Override public void keyTyped(java.awt.event.KeyEvent evt) { rdpanelKeyTyped(evt); } }); } public javax.swing.JPanel rdpanel; } 

Answer 1

You need to add a new FocusListener and a new KeyListener to the panel. If you want the keystrokes to be captured when the panel is in focus, get the FocusListener action to add the KeyListener and remove it.

Answer 2

In fact, you want the KeyboardManager to set the KeyEventPostProcessor or even an alternative dispatch for various components. I had the same problems in the NB app like you.

In this article, I used: ( developer.com )

I did this to capture key input events from any control in the panel (to trigger the OK button behavior automatically):

  KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager(); manager.addKeyEventPostProcessor(new EnterKeyListener()); 

And the listener:

  class EnterKeyListener implements KeyEventPostProcessor { @Override public boolean postProcessKeyEvent(KeyEvent e) { if (e.getKeyCode() == KeyEvent.VK_ENTER) { //Activate the refresh button: fireSearch(); return true; //halt further processing } return false; } } 

Answer 3

Remember to call setFocusable(true) as described in How to Write a Key Listener .

Answer 4

Add KeyListener to the panel:

 JPanel panel = new JPanel(); panel.addKeyListener(new KeyListener() { public void keyTyped(KeyEvent e) { … } public void keyReleased(KeyEvent e) { … } public void keyPressed(KeyEvent e) { … } }); 

Handle the event using the appropriate method.

As pointed out in others, you need to set panel.setFocusable(true); and, of course, you should add this component to your frame (or another parent component).

Answer 5

Depending on what you want to achieve, you can also find help here: http://java.sun.com/products/jfc/tsc/special_report/kestrel/keybindings.html