How to resolve this issue ?
1. Right Click on your project folder and select Properties.
2. Now Select Builders from the list of options at the left. 3. Now in the List of Builders, you would see two builders
1. Android Package Builder
2. Java Builder
Uncheck "Java Bulder" option and Click OK.
3. Now delete R.class file from the gen folder and do a Clean + Build ( If Build Automatically option is ON then this should happen automatically)