您是否将Facebook SDK集成到您的项目中？检查您的模块的 build.gradle ，并确保Facebook SDK处于依赖关系。如果没有，添加它并与Gradle同步，然后再次尝试。

Have you integrated the Facebook SDK into your project? Check the build.gradle of your module and make sure that Facebook SDK is in dependencies. If not, add it and sync with Gradle and then try again.

Facebook模块应该添加到 build.gradle 使用它的项目：

The Facebook module should be added to the dependencies in build.gradle of the project that uses it:

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile project(':facebook')
}

同样，Facebook模块应该导入 settings.gradle ：

As well, the Facebook module should be imported in settings.gradle:

include ':app', ':facebook'