Clojure JOptionPane

(See my full list of Clojure Swing examples and tutorials at Clojure Swing Interop)

Every complex GUI uses message dialogs. When using Clojure Swing interop, you will use the JOptionPane  for your message dialogs. Two keys to remember when using JOptionPane s, is that they should always be called from within the Event Dispatch Thread (EDT). Sometimes the JOptionPane  is shown by an ActionListener  that is already on the EDT, and sometimes you need to call invokeAndWait , because your current thread is not the EDT.

The other key point to remember with JOptionPane s is that you can associate the message dialog with a frame, or set the frame to nil . If a JOptionPane ‘s frame is set to nil , then the message dialog will center itself on the screen when it displays. If a JFrame  is provided to the JOptionPane , then the message dialog will center itself on the JFrame  it is associated with.

Here is a basic example that provides a button to click, and that displays a plain JOptionPane  with a message. The ActionListener  is called from the EDT, so the JOptionPane  is being called from the EDT.

Here is an example that shows a JOptionPane  that displays from a normal thread. The EDT must be explicitly called with invokeAndWait . The four most common types of message dialogs are shown.