Error: Unable to open class file R.java

You’ve just installed Eclipse , 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

5) Click Apply and then OK

Your problem should be resolved!