Application.java

Application.java

public class Application extends ContextWrapper implements ComponentCallbacks2 {
  public Application() {
        super(null);
    }
    /**
     * Called when the application is starting, before any activity, service,
     * or receiver objects (excluding content providers) have been created.
     * Implementations should be as quick as possible (for example using 
     * lazy initialization of state) since the time spent in this function
     * directly impacts the performance of starting the first activity,
     * service, or receiver in a process.
     * If you override this method, be sure to call super.onCreate().
     */
    public void onCreate() {
    }
    .....