Android Studio can't find library classes after Gradle build

Question

I'm trying to add a .jar library to my project into the /libs folder. Here is my grade.build:

    buildscript {
        repositories {
            mavenCentral()
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:0.4'
        }
    }
    apply plugin: 'android'

    dependencies {
        compile files('libs/android-support-v4.jar', 'libs/java-api-wrapper-1.2.0-all.jar')
    }

    android {
        compileSdkVersion 17
        buildToolsVersion "17.0.0"

        defaultConfig {
            minSdkVersion 15
            targetSdkVersion 16
        }
    }

After I add that, I build my project and there are no errors. But when I try to use the class in my code private ApiWrapper wrapper, I get an error:

Gradle: error: cannot find symbol class ApiWrapper

I can't quite find where the error is. Is my grade.build not ok, or am I supposed to build it some other way?

Solution 1

Using the command line, in the root of your project, run :
./gradlew clean && ./gradlew build

Then recompile your project in studio and you should see your new lib.

Solution 2

Set minifyEnabled to false for all your library projects in build.gradle. See accepted answer by Scott Barta in this thread.

See accepted answer by Scott Barta in this thread

Solution 3

Goto File ⇒ Invalidate Caches & Restart

Solved my problem

Solution 4

• As first option, i think will be enough Syncronizing the Project with Gradle Files.

• Another option, from the command line, run the batch file gradlew.bat located inside your project folder:

./gradlew clean && ./gradlew build

Solution 5

I had a similar situation where Android Studio couldn't find a library that definitely existed. Even though I was able to compile my project in Android Studio, run it from Android Studio in the emulator or on a physical device, and build it from the command line using gradlew, the Android Studio IDE complained Cannot resolve symbol 'ConstraintLayout'. I believe I had imported the library correctly because I followed Google's instructions: https://developer.android.com/training/constraint-layout/#add-constraintlayout-to-your-project.

Anyway, I ended up solving the problem as follows:

1. Close Android Studio
2. Delete the .idea folder in the project's directory
3. Open Android Studio
4. Re-import the project so Android Studio can regenerate the .idea folder

This in-fact solved the problem. I believe Android Studio somehow corrupted the .idea folder when I had done "Android Studio" > "Check for Updates" earlier in the day.

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Comments

[IgorGanapolsky]

Do you have any sub-projects, or just one main gradle project? I was getting a similar error in one of my sub-projects...

[IgorGanapolsky]

I thought if you run Build -> Rebuild Project it will run assembleDebug task for Gradle, which runs 'clean' task beforehand anyway.

[ajinkya gaurkar]

Thank you so much. This command line solution helped. I was tired finding solutions for my problem. But finally this worked

[Giacomo Mattiuzzi]

You have saved my day!! Thank you so much!!

[Omid Naji]

best answer, tnx

[Sal]

The first option worked for me, but the second one not.