Android Gradle cannot find symbol class Gson

Adding it as a dependency in the Project Structure settings is not enough. That setting is only for the IDE. To actually build, Gradle also needs to be aware of it. You must add the .jar file to your build.gradle file like so...

dependencies {
    compile files('libs/gson-2.2.4.jar')
}

I faced the same issue. I just added a single line as shown below in my build.gradle dependencies (without adding any jar in project structure) and it worked for me.

dependencies {
    compile 'com.google.code.gson:gson:2.2.+'
    compile 'com.android.support:support-v4:13.0.+'
    compile 'com.android.support:appcompat-v7:18.0.+'
}

Along with above, I found few more things which are required for this to work.

1. Make sure you have android:targetSdkVersion="18" in AndroidManifest.xml file.

   <uses-sdk
       android:minSdkVersion="10"
       android:targetSdkVersion="18" />
   

2. Make sure you have targetSdkVersion 18 in build.gradle file.

   defaultConfig {
       minSdkVersion 10
       targetSdkVersion 18
   }
   

3. Make sure you are connected to internet; so that jars will be downloaded from online central maven repository.

Just to add a point,

As of Gradle 1.7, jcenter() is a superset of mavenCentral()...so no need of adding and repositories directive.

Jars will be downloaded from online central jcenter repository. so adding just the following statement is working.

dependencies {
compile 'com.google.code.gson:gson:2.2.+'
}