How do I check if the caps lock key is pressed?

user_1144248 0
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Alright, before this gets flagged as a possible duplicate, I've already tried the following code:

Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK)

And it is always returning false for me [see below]. Could someone confirm if this is supposed to be working, and I'm misusing it, or if it's known to be broken? If it is in fact broken, does anyone have a better method to use?

EDIT:

Alright, just found out something more. It appears to just return what it was at the begining of my programs launch. If I start the program with it on, it says its on, and vice versa. Here's my code:

while (true) {
    boolean isOn = Toolkit.getDefaultToolkit().getLockingKeyState(
        KeyEvent.VK_CAPS_LOCK);
    System.out.println("Caps lock is now: " + (isOn ? "ON" : "off"));
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
    }
}

And that's just always printing out whatever it started as

(ex. if I start with caps lock on, even if I toggle it off right after, it prints:

Caps lock is now: ON

Caps lock is now: ON

Caps lock is now: ON

Caps lock is now: ON

etc., if I start with it off, it will print off no matter what)

capslock java
3 Answers

Looks like this was always broken or at least since Java 1.3 (see Bug 4414164).

Not sure for other platforms, but for Windows I can say this: State change of Caps Lock can be detected, but only if your awt client has the focus. However, there is this workaround which works for me:

boolean isCapsLockOn() {
    java.awt.Robot robot = new java.awt.Robot();
    robot.keyPress(KeyEvent.VK_CONTROL);
    robot.keyRelease(KeyEvent.VK_CONTROL);
    return Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK);  
}

Contraint: Your awt app must have the focus before calling isCapsLockOn.

Note: Your robot might press any other key which is not harmful to your app. Might depend on your use case.

user_19482520
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