About Application to get context, getApplicationContext method Null pointer problem.

The application gets the context, and the premise must be initialized in the oncreate method in the application.

solve:

public class AppUtils {

    private static Application application;

    public static void setApplication(Application application) {
        if (AppUtils.application != null) {
            throw new IllegalStateException("application already holded 'application'.");
        }
        AppUtils.application = application;
    }
    public static Context getContext() {
        return application.getApplicationContext();
    }
}

Initialize in applicaition class

@Override
public void onCreate() {
    super.onCreate();
    // Context
    AppUtils.setApplication(this);
    Fresco.initialize(this);
    initPackageName();
}

Do this by

Context context = AppUtils.getContext();