Shaaf's blog

Here I would like to demonstrate a simple use of JMenuItems being used with Single Listener for the entire system. A simple sample of use would probably be SingleInstance Desktop Application. Lets see how that is done here. First lets create a OneListener class that should be able to listen to ActionEvents and also be able to add Commands to itself. Please refer to my previous post on Command,Singleton if you would like to see more about this patterns and there usage.

By using the command pattern you are seperating the operation from the invoking object. And just because of that it becomes easier to change the command without chagning the caller/s. This means that you could use Command pattern when you might have the following situation You want to parameterize objects to perform an action You want to specify, execute and queue requests at different times. Just to quickly start you need a command object, An interface will keep it easy going in this case, thus providing you with the option of extending other classes e.