R.layout.main 无法找到/无法解析符号 R

Question

All of a sudden I am getting red underlinings under my references to elements eg R.textboxID. I did some googling around and I found that the error occurs when Android Studio can't generate your R.java file correctly.

My question is how does Android Studio just suddenly not know how to generate my R file correctly when it was generating it well all along? How can I fix this problem permanently?

Answer 1

This usually happens when some unexpected event, like an IDE error occurs and the project needs to be rebuilt. Just hit Build -> Rebuild Project. Sometines this may occur after you modify your build.gradle file, and sometimes, if it only occurs within one of your classes, you might not be inflating it correctly.

Answer 2

Select Build > Clean Project from the Android Studio toolbar, wait a few moments, and then build your project by selecting Build > Rebuild Project.

If a single clean/rebuild cycle doesn't work, then try repeating this process a few times, multiple clean/rebuild cycles in quick succession usually work.

Answer 3

Gradle sync succeded? Try one of the following:

• Clean end rebuild your project
• From Android studio menu: File->Invalidate cache/restart, then clean and rebuild project
• If none of above helps, close Android studio and remove ~/.gradle directory. Then run Android Studio, open your project, wait for finish sync, then rebuild project

Also make sure your gradle configuration is correct and resource xml files syntax is correct.

Answer 4

Please check the import statements at the top of file some times there may be import com.android.R will be there so you should delete that statement and it will work fine