How to programmatically close a JFrame?

Detailed Breakdown: Closing techniques for seasoned coders

The Fast answer gives you an immediate solution. But if you're aiming for a more versatile technique to close your JFrame, especially when additional operations are to be performed before closing or when working with multiple frames, stick around.

Emulating the hands of a user

// If you miss that friend who always tries to close your JFrame, this is how you replicate the stunt. Quite frequently, we need to simulate the user experience, including the action of clicking the close button. This notifies all WindowListeners attached to your JFrame, enabling your application to respect the sequence of window events, just like a real user-triggered close:

WindowEvent wev = new WindowEvent(myFrame, WindowEvent.WINDOW_CLOSING);
Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(wev); // Siri, close the window!
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Graceful exit: Not just bailing out

Exiting an application gracefully is like leaving a house party without causing a scene. The classic System.exit(0); does just that but before exiting, make sure all existing frames are disposed if you're hosting multiple windows:

for(Frame frame : Frame.getFrames()) { // Like a good host, clean up after the party!
    frame.dispose();
}
System.exit(0); // Then make your graceful exit
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Hide not dispose, the magic trick

Some frames you don't wish to dispose, but only make invisible (Yes, we all want to be a magician sometimes!). The trick, my friend, is setVisible(false);:

myFrame.setVisible(false); // Now you see me... now you don't!
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Dealing with DO_NOTHING_ON_CLOSE

In some scenarios, we set the JFrame with DO_NOTHING_ON_CLOSE operation. It's like procrastinating unless we have no choice but to close. Here, explicitly sending a WINDOW_CLOSING event will not result in the frame being closed:

myFrame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE); // Procrastination level: JFrame
// ... Inside some action listener or method
if (shouldClose()) { // Should I? Alright then...
    myFrame.dispatchEvent(new WindowEvent(myFrame, WindowEvent.WINDOW_CLOSING));
}
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Pro-Level Tactics and Considerations

Complex scenarios such as thread management, multiple windows, or preventing unintended behavior, call for a deeper knowledge pool.

Timing: Sequencing events for multiple frames

With multiple JFrames in play, it is important to master the art of timing closures in a sequence. This prevents data loss or state inconsistencies by ensuring that the appropriate window lifecycle methods are called for each individual frame.

Single targeted closure: No domino effect here

Sometimes, other windows need to stay open when one closes. Careful handling of closing operations can prevent a domino effect. Trigger close events or dispose() methods only for the specific frames you wish to close.

Managing thread and window states

Be wary of meddling threads that shouldn't be managing the GUI. Always prefer GUI manipulations on the Event Dispatch Thread (EDT), to prevent any UI faux pas:

SwingUtilities.invokeLater(() -> myFrame.dispose()); // Swing Utilities, saving the day!
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