Check out the JOptionPane class. It has a number of convenient methods for creating simple dialogs. Also you may find it useful to have some sort of GUI utility class which has additional methods for any operations you find yourself doing more than once. E.g. I have a method
showError(
String message, Throwable t)
which creates a pop-up for many error messages, which has a "see details" button which allows the user to look at the stack trace of an error, if they want. (While hiding it from the majority of users who would not want to see it.) This was too complex to set up with a single JOptionPane call, but it's useful to have a simple method call to do it, so I spent a little more time making the custom method. You may find similar situations.