Q:

Can't create a runnable jar file via Eclipse

I made a Java project with Eclipse. The project has a public static void main(String[] args) method in it. 
When I try to export it to a runnable jar, the launch configuration does not include the project I created so I can't create the jar for the project. Any ideas why?

A:

Try creating a new launch configuration from scratch:

Run -> Run Configurations...
Right click "Java Application" in the list on the left and select New
On the right enter a descriptive name.
In the Main tab browse for your project and search for and select the appropriate main class.
Close the dialog.

Now try exporting your runnable JAR again using that run configuration.

A:

Either run the project once to automatically create a run configuration or go into the project options and create one manually.

