Android /FBReaderJ/gen already exists but is not a source folder. Convert to a source folder or rename it

I downloaded the FBReaderJ source, its say: " /FBReaderJ/gen already exists but is not a source folder. Convert to a source folder or rename it"

I can't run it, why? I can't delete "gen" too.

Try this, it helped me:

1. Right click on the project and go to "Properties"
2. Select "Java Build Path" on the left
3. Open "Source" tab
4. Click "Add Folder..."
5. Check "gen" folder and click Ok and Ok again
6. Again right click on the project and in the "Android Tools" click on "Fix Project Properties"

There are several things I do to fix that.

• Delete the gen folder
• Use project > clean
• Properties > android tools > fix project properties

Try creating a new Android project in your Eclipse IDE, then copying the hidden .classpath file from the new project into your existing one. You can then delete the extra Android project.

Then do the steps above. Delete the /gen folder, and do cleaning (Project -> Clean, Android Tools -> Fix Project Properties).

The issue for me was that the downloaded .classpath was set to place the source .class files into /gen, which was supposed to have R.class files. Eclipse wanted the source .class files in /bin, which is what Eclipse's automatically generated .classpath gives you. If you feel comfortable editing the .classpath yourself (it's not particularly difficult to read), you can make the modifications in-place without bothering to create a new Android project.

Simpley it means your project is not in workspace again import the project

Go to Project -> Properties -> Java Compiler. Select 'Compiler compilance level' to 1.6+. If you don't have higher compiler versions available, you may be running on an old Java installation, get it updated