Help with “Error: Unable to open class file R.java” when building an Android App for the first time in Eclipse This is just a really, quick and dirty post to help resolve this issue.
Problem:
You’ve just installed Eclipse (5.2.x at the time of this writing), and attempted to create your first Android Application. When clicking create, you see an error similar to this:
Error: Unable to open class file R.java Solution:
The “Build Path” for your Java environment is not setup correctly in Eclipse. To fix this, follow these steps:
1) Open the Preferences Window by clicking Window -> Preferences
2) Find the Java section and expand it
3) Select Build Path
4) Change the value of Source and output folder from Folders to Project