Q 9 – Is it mandatory to call onCreate() and onStart() in android? It is not mandatory, the program will work perfectly without fail, but the programmer has to implement the life cycle of activity.
Why we use onCreate method in Android?
onCreate(Bundle savedInstanceState) Function in Android:
Basically Bundle class is used to stored the data of activity whenever above condition occur in app. onCreate() is not required for apps. But the reason it is used in app is because that method is the best place to put initialization code.
Is it possible activity without UI in Android?
The answer is yes it’s possible. Activities don’t have to have a UI. It’s mentioned in the documentation, e.g.: An activity is a single, focused thing that the user can do.
What is transient data in Android *?
transient means temporary data while persistent means permanent data.
What is off line synchronization in android?
Synchronizing data between an Android device and web servers can make your application significantly more useful and compelling for your users. For example, transferring data to a web server makes a useful backup, and transferring data from a server makes it available to the user even when the device is offline.
What is onCreate () method?
onCreate is used to start an activity. super is used to call the parent class constructor. setContentView is used to set the xml.
What is the use of setContentView in Android?
SetContentView is used to fill the window with the UI provided from layout file incase of setContentView(R. layout. somae_file). Here layoutfile is inflated to view and added to the Activity context(Window).
What is an interface in Android?
Android provides a variety of pre-built UI components such as structured layout objects and UI controls that allow you to build the graphical user interface for your app. Android also provides other UI modules for special interfaces such as dialogs, notifications, and menus. To get started, read Layouts.
What is Android ViewGroup?
A ViewGroup is a special view that can contain other views (called children.) The view group is the base class for layouts and views containers. This class also defines the ViewGroup. Android contains the following commonly used ViewGroup subclasses: LinearLayout.
How do you kill an activity?
Launch your application, open some new Activity, do some work. Hit the Home button (application will be in the background, in stopped state). Kill the Application — easiest way is to just click the red “stop” button in Android Studio. Return back to your application (launch from Recent apps).
What is singleton class in Android?
A singleton is a design pattern that restricts the instantiation of a class to only one instance. Notable uses include controlling concurrency and creating a central point of access for an application to access its data store. This example demonstrate about How to use singleton class in android.
How does JNI work on Android?
It defines a way for the bytecode that Android compiles from managed code (written in the Java or Kotlin programming languages) to interact with native code (written in C/C++). JNI is vendor-neutral, has support for loading code from dynamic shared libraries, and while cumbersome at times is reasonably efficient.
What is super onCreate in Android?
By calling super. onCreate(savedInstanceState); , you tell the Dalvik VM to run your code in addition to the existing code in the onCreate() of the parent class. … The code in the framework classes handles stuff like UI drawing, house cleaning and maintaining the Activity and application lifecycles.