Question

I’m trying to do a very simple thing : trigger an action when the user presses on a key of the keyboard

the keys I would like to map are :

• key +
• key –
• key delete
• ctrl+c

• ctrl+v

  public class keytestmain extends Applet{

  //Called when this applet is loaded into the browser.
  public void init() {
      //Execute a job on the event-dispatching thread; creating this applet's GUI.
      try {
          SwingUtilities.invokeAndWait(new Runnable() {
              public void run() {
                  JLabel lbl = new JLabel("Hello World");
                  add(lbl);
                  JPanel p = new JPanel();
                  p.setBackground(Color.green);
                  p.setMinimumSize(new Dimension(100,100));
                  p.setPreferredSize(new Dimension(100,100));
                  p.setMaximumSize(new Dimension(100,100));
                  InputMap inputMap = new InputMap();
  
                  // Add a KeyStroke
                  inputMap.put(KeyStroke.getKeyStroke("SPACE"), "actionName");
  
                  inputMap.setParent(p.getInputMap(JComponent.WHEN_FOCUSED));
                  p.setInputMap(JComponent.WHEN_FOCUSED, inputMap);
                  add(p);
              }
          });
      } catch (Exception e) {
          System.err.println("createGUI didn't complete successfully");
      }
  
  }
  

  }

but nothing works

Any ideas?

Answer 1

I would use Key Bindings, instead of KeyListeners. This is more reliable as it doesn’t have many focus issues. Also KeyListeners is a relatively old AWT solution, so depending on your JDE, the command may have been depracated.