Android Studio can't find library classes afte

问题:

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?

回答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.

回答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

回答3:

• 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

回答4:

Goto File ⇒ Invalidate Caches & Restart

Solved my problem

回答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.