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Android

Jonathan Grieve
MOD
Jonathan Grieve
Treehouse Moderator 91,253 Points
Posted by Jonathan Grieve
Jonathan Grieve
Treehouse Moderator 91,253 Points

Cannot resolve symbol "R" in Android Project

I understand this is probably a common error in Android but I've been trying to flush this bug out for a couple of days.

I have a few build errors in my project.

Information:Gradle tasks [:app:generateDebugSources, :app:generateDebugAndroidTestSources, :app:mockableAndroidJar, :app:prepareDebugUnitTestDependencies]
[file path]
Error:(10) No resource identifier found for attribute 'layout_constraintRight_toTopOf' in package 'uk.co.jonniegrieve.newinteractivestory'
[file path]
Error:(10) No resource identifier found for attribute 'layout_constraintRight_toTopOf' in package 'uk.co.jonniegrieve.newinteractivestory'
Error:Execution failed for task ':app:processDebugResources'.
> com.android.ide.common.process.ProcessException: Failed to execute aapt

And in my project, where there's any reference to the "R" package an error is returned which pops up as Cannot Resolve Symbol "R"

I've gone to Stack Overflow. I've tried importing variable classes I've tried updating Gradle, cleaning/rebuilding the project I've tried updating the SDK multiple times but the bug won't go away.

Here's the project, https://github.com/jg-digital-media/android-interactive-storyapp

Any ideas what I need to update? Thanking you! :)

1 Answer

Christopher Augg
Christopher Augg
21,223 Points
Christopher Augg
Christopher Augg
21,223 Points

Jonathan,

I cloned your project and found the following in your activity_story.xml:

        app:layout_constraintHorizontal_bias="0.375"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintRight_toTopOf="@+id/storyTextView"

The last line seems to be the issue. I changed the line and added a constraintBottom_toTopOf :

        app:layout_constraintBottom_toTopOf="@+id/storyTextView"
        app:layout_constraintHorizontal_bias="0.375"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"

That allowed it to compile and run once completed. Please let me know if this works for you.

Chris

Jonathan Grieve
Jonathan Grieve
Treehouse Moderator 91,253 Points
Jonathan Grieve
Jonathan Grieve
Treehouse Moderator 91,253 Points

Bingo!

I saw the errors about the constraints but I had no idea fixing those would clear the error with the R package.

Any idea why that would confuse Android so much? I don't understand. Thanks :)

Christopher Augg
Christopher Augg
21,223 Points
Christopher Augg
Christopher Augg
21,223 Points

Heya. Glad it is working now. I honestly never ran into this issue before but according to Constraint Layout Docs, the list of available constraints within resources are:

  • layout_constraintLeft_toLeftOf
  • layout_constraintLeft_toRightOf
  • layout_constraintRight_toLeftOf
  • layout_constraintRight_toRightOf
  • layout_constraintTop_toTopOf
  • layout_constraintTop_toBottomOf
  • layout_constraintBottom_toTopOf
  • layout_constraintBottom_toBottomOf
  • layout_constraintBaseline_toBaselineOf
  • layout_constraintStart_toEndOf
  • layout_constraintStart_toStartOf
  • layout_constraintEnd_toStartOf
  • layout_constraintEnd_toEndOf

Therefore, I think the layout_constraintRight_toTopOf is not in R, and no identifier for it can be found. It looks like constraints need to connect on their respective axis. Hope this helps.

Chris