Sounds like a job for JDialog to me.  Extend it, and add your own getter
functions.

For example, let's say you have a custom JDialog called MyJDialog, and
you created an internal property called userInput of type String, which
you created a getter function for called public String getUserInput();
In that case, here's the code to go in your JFrame.

MyJDialog dialog = new MyJDialog(this, true); // make it modal (means
nothing else can have focus until this dialog is disposed)
dialog.show();
String result = dialog.getUserInput();

If you want the user to be able to still access the JFrame while the
JDialog is showing, pass in a value of false as the second parameter to
the constructor.

John Davison