How to get package name from anywhere?

An idea is to have a static variable in your main activity, instantiated to be the package name. Then just reference that variable.

You will have to initialize it in the main activity's onCreate() method:

Global to the class:

public static String PACKAGE_NAME;

Then..

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    PACKAGE_NAME = getApplicationContext().getPackageName();
}

You can then access it via Main.PACKAGE_NAME.

If you use gradle build, use this: BuildConfig.APPLICATION_ID to get the package name of the application.

If with the word "anywhere" you mean without having an explicit Context (for example from a background thread) you should define a class in your project like:

public class MyApp extends Application {
    private static MyApp instance;

    public static MyApp getInstance() {
        return instance;
    }

    public static Context getContext(){
        return instance;
        // or return instance.getApplicationContext();
    }

    @Override
    public void onCreate() {
        instance = this;
        super.onCreate();
    }
}

Then in your manifest you need to add this class to the Name field at the Application tab. Or edit the xml and put

<application
    android:name="com.example.app.MyApp"
    android:icon="@drawable/icon"
    android:label="@string/app_name"
    .......
    <activity
        ......

and then from anywhere you can call

String packagename= MyApp.getContext().getPackageName();

Hope it helps.

If you use the gradle-android-plugin to build your app, then you can use

BuildConfig.APPLICATION_ID

to retrieve the package name from any scope, incl. a static one.