Eclipse `allow output folders for source folders`

Question

When creating a new Java (not JavaEE) project in Eclipse IDE, I see an option that says Allow output folders for source folders.

What is that for?

Answer 1

It allows defining a separate output folder (i.e. the folder where eclipse creates the compiled .class files) per source folder, instead of storing all the .class files of all source folder in the same output folder.

Answer 2

One little additional hint. I had the same problem, I checked the box, left the dialog and it was unchecked again when I came back.

The solution is very simple, but a little bit hidden for newcomers:

After you have checked that box, you need to open the trees under each of your source folders. You will see a new entry "Output folder" there now, where you can specify individual folders. For instance you keep the output of src/ to go to bin/, but define a specific output folder for test/ (e.g. bin.test/). That way you can grab your real application code from bin/ later (e.g. for putting it in a JAR with an ANT script), but keep bin.test aside.