Android Studio: Gradle: error: cannot find symbol variable

Question

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.

Answer 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)

Answer 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.

Answer 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\""

Answer 4

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

Answer 5

make sure that the imported R is not from another module. I had moved a class from a module to the main project, and the R was the one from the module.

Answer 6

Make sure you have MainActivity and .ScanActivity into your AndroidManifest.xml file:

<activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".ScanActivity">

    </activity>

Answer 7

Make sure your variables are in scope for the method that is referencing it. For example I had defined a textview locally in a method in the class and was referencing it in another method.

I moved the textview definition outside the method right below the class definition so the other method could access the definition, which resolved the problem.

Answer 8

Another alternative to @TouchBoarder's answer above is that you may also have two layout files with the same name but for different api versions. You should delete the older my_file.xml file

my_file.xml
my_file.xml(v21)

Answer 9

Make sure that the control you are referring to in the XML layout file really exists, even if it's not being used.

I had this after when I did "removed unused resources" refactory.

For example, you will get this error if there is no progressBar in the layout.

rootView = inflater.inflate(R.layout.fragment_stats, container, false);

mProgressBar = rootView.findViewById(R.id.progressBar);

Answer 10

Please check you accidentally added the XML file into the layout folder.

Answer 11

Make Sure your package name correct at top, wrong package name may cause this issue.