using keybinding and Action Map in Java for shortcut keys for buttons

Question

I am making a program where I want to have shortcuts for all the buttons in my program. example ctrl+a executes button 1.

I also want these shortcuts to be user changeable

so this is the code i am using to add a key binding

   InputMap IM = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);

   IM.put(KeyStroke.getKeyStroke(KeyEvent.VK_B, InputEvent.CTRL_DOWN_MASK | 
          InputEvent.ALT_DOWN_MASK), "BUTTON ONE ID");

  ActionMap actionMap = component.getActionMap();
    actionMap.put("BUTTON ONE ID", new AbstractAction() {
        @Override
        public void actionPerformed(ActionEvent e) {
            actionListener.actionPerformed(e);
        }
    });

Now since i want these to be user changeable, i want to be able to use the "BUTTON ONE ID" on the third line to get its information. I want to be able to know what key i entered for it and whether or not you need to hold ctrl or alt for the shortcut

so i would want the following code

if("BUTTON ONE ID"){
  //print KeyEvent/keyCode info and if we need to hold ctrl, alt or shift?
  //and then i want to be able to change the key bindings 

}

How do I do this using the "BUTTON ONE ID" or is their a better way of doing this. Thanks

Answer 1

Okay, this a quick example of how you might allow the user to generate their own key strokes. It basically captures the state of the CTRL , SHIFT , ALT and META keys and records the last none "modifier" key press.

It provides a simple getKeyStroke method to return the key stroked that would be generated by the configured states, in this example, you will find that it prints the KeyStroke when a key is "typed", which is done for debugging

import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToggleButton;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class ExampleLKeyConfig {

    public static void main(String[] args) {
        new ExampleLKeyConfig();
    }

    public ExampleLKeyConfig() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new KeyCapturePane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class KeyCapturePane extends JPanel {

        private JToggleButton ctrlKey;
        private JToggleButton altKey;
        private JToggleButton shiftKey;
        private JToggleButton metaKey;
        private JButton strokeKey;

        private int keyCode;

        public KeyCapturePane() {
            setBorder(new EmptyBorder(10, 10, 10, 10));
            setLayout(new GridBagLayout());

            ctrlKey = new JToggleButton(KeyEvent.getModifiersExText(KeyEvent.CTRL_DOWN_MASK));
            altKey = new JToggleButton(KeyEvent.getModifiersExText(KeyEvent.ALT_DOWN_MASK));
            shiftKey = new JToggleButton(KeyEvent.getModifiersExText(KeyEvent.SHIFT_DOWN_MASK));
            metaKey = new JToggleButton(KeyEvent.getModifiersExText(KeyEvent.META_DOWN_MASK));
            strokeKey = new JButton("-");

            updateMetaState(new KeyEvent(this, 0, 0, 0, 0, ' '));

            add(ctrlKey);
            add(altKey);
            add(shiftKey);
            add(metaKey);
            add(strokeKey);

            setFocusable(true);
            addKeyListener(new KeyAdapter() {

                @Override
                public void keyPressed(KeyEvent e) {
                    updateMetaState(e);
                    int code = e.getKeyCode();
                    if (code != KeyEvent.VK_CONTROL && code != KeyEvent.VK_ALT && code != KeyEvent.VK_SHIFT && code != KeyEvent.VK_META) {
                        strokeKey.setText(KeyEvent.getKeyText(code));
                        keyCode = code;
                    }
                }

                @Override
                public void keyReleased(KeyEvent e) {
                }

                @Override
                public void keyTyped(KeyEvent e) {
                    System.out.println(getKeyStroke());
                }

            });

            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    requestFocusInWindow();
                }
            });
        }

        protected int getModifiers() {
            return (ctrlKey.isSelected() ? KeyEvent.CTRL_DOWN_MASK : 0)
                            | (altKey.isSelected() ? KeyEvent.ALT_DOWN_MASK : 0)
                            | (shiftKey.isSelected() ? KeyEvent.SHIFT_DOWN_MASK : 0)
                            | (metaKey.isSelected() ? KeyEvent.META_DOWN_MASK : 0);
        }

        public KeyStroke getKeyStroke() {
            return KeyStroke.getKeyStroke(keyCode, getModifiers());
        }

        protected void updateMetaState(KeyEvent evt) {
            updateMetaState(ctrlKey, evt.isControlDown());
            updateMetaState(altKey, evt.isAltDown());
            updateMetaState(shiftKey, evt.isShiftDown());
            updateMetaState(metaKey, evt.isMetaDown());
        }

        protected void updateMetaState(JToggleButton btn, boolean isPressed) {
            if (isPressed) {
                btn.setSelected(!btn.isSelected());
            }
        }

    }

}

Now, this is rough and ready. I had it print some interesting characters while I was testing so you might want to run through it and see which keys you might want to filter out (hint Caps Lock might be one ;))

Now, with this in hand, you just need to change the InputMap

KeyStroke ks = ...;
IM.put(ks, "BUTTON ONE ID");

and it will automatically update the bindings