use the java command instead of javaw and you should get an error message on the screen.
Copy and paste the message here if you have questions about it.
To copy the contents of the command prompt window:
Click on Icon in upper left corner
Select 'Select All' - The selection will show
Click in upper left again
Select Edit and click 'Copy'
In Netbeans, you can open the project properties and look at the "Run" category. There is an entry for Main Class there. Be sure that is set to the class you are wanting to run and then clean and build your project.