CODEWITHSUNDEEP
javaswingkeyboardactionkeyboard-events
Grumpy ol' Bear
Grumpy ol' Bear

Reputation: 745

Trouble implementing Keyboard actions

I don't get how do implement Keyboard actions at all.

Mouse clicks, Buttons, Textfield, Textarea I get just fine, Keyboard is like the Chinese wall to me.

I have something like this, and I'd like to implement the Keyboard to close when I press "C":

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class TestGUI
{
    private KeyboardListener anEventListener;

    public TestGUI()
    {
        initGUI();
    }

    private void initGUI()
    {       
        //Prepare Frame
        JFrame myFrame = new JFrame();
        myFrame.setTitle("Test");
        myFrame.setSize(550, 500);
        myFrame.setLocation(600, 100);
        myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myFrame.setLayout(null);

        KeyboardListener anEventListener = new KeyboardListener();

        //Show Frame
        myFrame.setVisible(true);

    }

    public static void main(String args[])
    {
        SwingUtilities.invokeLater(new Runnable() 
        {
            public void run() 
            {
                new TestGUI();
            }
        });
    }

    class KeyboardListener implements KeyListener
    {

      public void keyPressed (KeyEvent event)
      { 
        if (event.getKeyCode() == KeyEvent.VK_C)
        { 
            System.exit(0);
        }
      }          

      public void keyReleased(KeyEvent event)
      {

      }
      public void keyTyped (KeyEvent event)
      {

      }
    } 



}

Upvotes: 0

Views: 695

Answers (4)

Howard
Howard

Reputation: 39217

Just add the line

myFrame.addKeyListener(anEventListener);

to register your listener within your frame and it will work fine.

Note: This will only handle the key events associated with your frame. If you have other components around you might want to handle it differently (see also how to use key bindings).

In your case you can build a version with key bindings quite easily:

JComponent rootPane = myFrame.getRootPane();
rootPane.getInputMap().put(KeyStroke.getKeyStroke("C"), "closeThisOne");
rootPane.getActionMap().put("closeThisOne", new AbstractAction() {
    @Override
    public void actionPerformed(ActionEvent e) {
        System.exit(0);
    }
});

Upvotes: 1

camickr
camickr

Reputation: 324207

and I'd like to implement the Keyboard to close when I press "C":

Then you should create a custom Action and use a JMenu with a close menu item and an accelerator.

The ExitAction from Closing an Application will do this for you.

Upvotes: 3

fireshadow52
fireshadow52

Reputation: 6526

I would start by checking out Key Bindings. This is more reliable than KeyListeners as it doesn't have many focus issues. Also, KeyListeners is an old AWT solution for problems like this.

Upvotes: 3

Thorn G
Thorn G

Reputation: 12776

You haven't attached your KeyboardListener to a component. You also aren't using the anEventListener field defined in your class -- it's being shadowed inside initGUI.

Upvotes: 1

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