Android Studio: Gradle: error: cannot find symbol variable

I was working on my app and everything was normal until I tried to display image in java.

I ran the app once and it ran normally, the picture was displayed. After that it asked me to import some libraries and I imported them. After that I got errors for my activities.

Errors like:

Gradle: error: cannot find symbol variable activity_main
Gradle: error: cannot find symbol variable button1
Gradle: error: cannot find symbol variable button2
Gradle: error: cannot find symbol variable textView
Gradle: error: cannot find symbol variable secondActivity

In MainActivity I have imported these libraries:

import android.R;
import android.content.Intent;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.Button;

and in secondActivity these:

import android.R;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

Does anyone know how to fix this?

EDIT: I deleted import android.R; and now it works normally.

Solution 1:

You shouldn't be importing android.R. That should be automatically generated and recognized. This question contains a lot of helpful tips if you get some error referring to R after removing the import.

Some basic steps after removing the import, if those errors appear:

• Clean your build, then rebuild
• Make sure there are no errors or typos in your XML files
• Make sure your resource names consist of [a-z0-9.]. Capitals or symbols are not allowed for some reason.
• Perform a Gradle sync (via Tools > Android > Sync Project with Gradle Files)

Solution 2:

If you are using multiple flavors?

-make sure the resource file is not declared/added both in only one of the flavors and in main.

Example: a_layout_file.xml file containing the symbol variable(s)

src:

flavor1/res/layout/(no file)

flavor2/res/layout/a_layout_file.xml

main/res/layout/a_layout_file.xml

This setup will give the error: cannot find symbol variable, this is because the resource file can only be in both flavors or only in the main.

Solution 3:

If you are using a String build config field in your project, this might be the case:

buildConfigField "String", "source", "play"

If you declare your String like above it will cause the error to happen. The fix is to change it to:

buildConfigField "String", "source", "\"play\""

Solution 4:

Open project in android studio click file and click Invalidate Caches/Restart