创建一个类，将其命名为 App 并从 MultiDexApplication 进行扩展，如下所示:

create a class lets name it App and extend from MultiDexApplication like this:

import android.support.multidex.MultiDexApplication;

public class App extends MultiDexApplication {
    //you can leave this empty or override methods if you like so the thing is that you need to extend from MultiDexApplication
}

在清单中添加 App 作为应用名称，就像这样

in your manifest add App as your application name just like this

<application
        android:name=".App" // <<< this is the important line!
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name">

添加完所有内容后，进行一个干净的构建，它现在应该可以工作了:).

After adding everything make a clean build and it should work now :).