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 th

Answer 1

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 2

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 3

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 4

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 5

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 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>