为什么找不到我创建的 MainActivity.java 文件的布局？

Question

I was following the instructions online in android app development course for beginners and I encountered this problem.

The instructor was demonstrating how we could use the layouts we created for the activity. He was able to find the layout he created using R.layout. , but I could not.

The activity_main_listview.xml is the View that I created. I am an absolute beginner so I don't know what is wrong here.

Is there any way I could resolve this problem?

I have tried to Synchronize both the .xml files and the MainActivity.java file. I have also tried to clean and rebuild the project.

This is a picture of the part where it did not work

Answer 1

I had the same problem, fixed by replacing R with com.example.appname.R obviously put your package reference in there instead. Or just add this line to your file:

import com.testapp.activitydemo.package.R

Or even better, try removing this line from your code if exists:

import android.support.compat.R

If your XML's contain errors your generated file might not build try erasing most of their content and making sure id's and file names are not duplicated and no capitals and spaces are used. If it works you can start adding stuff.

Another note:

Sync Project With Gradle File Once you update the Gradle plugin you need to sync project with the Gradle file. Open android studio and click on Files > Sync Project with Gradle Files option.

Clean and Rebuild Project The most effective solution is the simplest: clean and rebuild your project. Select Build > Clean Project from the Android Studio toolbar, wait a few moments, and then build your project by selecting Build > Rebuild Project.

Answer 2

This is common problem which occurs with Android Studio!

Its not your problem, it is bug of Android Studio!

To resolve this, Just Clean your project and Restart Android Studio!