Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Android Build a Simple Android App with Java Testing and Debugging Toast Notifications

Posted by Manjeeth Reddy Patlolla
Manjeeth Reddy Patlolla
175 Points

I tried all the steps. But there is an error. It says 'Cannot Resolve Symbol R'

In MainActivity.java file, we use command findViewById(R.id.factTextView) Here, it says Cannot Resolve symbol 'R'. Error: failed linking file resources

1 Answer

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

R is a class file automatically generated by Android Studio for your project. If you have an error related to it your first step should be to do a Clean then Rebuild project from the Build menu. This will usually fix the issue but keep an eye out for error messages that will point out the problem (With R, usually a mistake in an XML file).