How to Implement Command-W to Close a Window in Java or Clojure on Mac OS

Question

How can I implement the Command-W shortcut to close a window in a Java or Clojure application on Mac OS?

// Sample Java code to implement Command-W listener
KeyStroke keyStroke = KeyStroke.getKeyStroke(KeyEvent.VK_W, KeyEvent.META_MASK);
inputMap.put(keyStroke, "closeWindow");
actionMap.put("closeWindow", new AbstractAction() {
    public void actionPerformed(ActionEvent e) {
        // Close the window logic goes here
        dispose();
    }
});

Answer

In both Java and Clojure, handling system key combinations like Command-W requires setting up key bindings. On Mac OS, the Command (⌘) key is often used for shortcuts. This guide provides step-by-step instructions and sample code to help you implement the Command-W functionality in your applications.

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

public class CloseWindowExample extends JFrame {
    public CloseWindowExample() {
        setTitle("Close Window Example");
        setSize(400, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Key binding for Command-W
        InputMap inputMap = getRootPane().getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        ActionMap actionMap = getRootPane().getActionMap();

        KeyStroke closeKeyStroke = KeyStroke.getKeyStroke(KeyEvent.VK_W, InputEvent.META_DOWN_MASK);
        inputMap.put(closeKeyStroke, "closeWindow");

        actionMap.put("closeWindow", new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
                dispose(); // Closes the window
            }
        });
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            CloseWindowExample example = new CloseWindowExample();
            example.setVisible(true);
        });
    }
}

Causes

The application must be set up to listen for keyboard events.
The Command key behavior may differ across operating systems, necessitating specific handling for Mac OS.

Solutions

Use key binding in Java Swing to associate Command-W with a window close action.
Implement similar functionality using libraries in Clojure such as Seesaw that leverage Java's capabilities.

Common Mistakes

Mistake: Not checking for Mac OS specific key bindings.

Solution: Ensure your application checks the operating system at runtime to handle key events appropriately.

Mistake: Using the wrong key mask for Command key.

Solution: Always use InputEvent.META_DOWN_MASK for Mac OS when binding key strokes for Command key shortcuts.

Helpers

Command-W close window
Java Mac OS shortcut
Clojure key bindings
Java key event handling
Close window in Java
Clojure Mac OS applications