你有没有整合Facebook的SDK到你的项目？检查 build.gradle 你的模块，并确保Facebook的SDK是依赖关系。如果没有，添加它和摇篮同步，然后重试。

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.

在Facebook的模块应该被添加到依赖于 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')
}

同时，Facebook的模块应在 settings.gradle 输入：

include ':app', ':facebook'