While creating an android application, android provides various stages to managing the UI of application and during transition system always notifies you via a lifecycle callback method. There are 7 android activity lifecycle methods like onCreate, onStart, onResume, onPause, onStop, onDestroy, and onRestart.
In this blog, we will explore Top 10 most important Android Activity Lifecycle Interview Questions with Example in 2024.
OnCreate() -
In this blog, we will explore Top 10 most important Android Activity Lifecycle Interview Questions with Example in 2024.
Top 10 most important Android Activity Lifecycle Interview Questions with Example in 2024
Ques-1: What is Android Activity Lifecycle?
Ans-1: Android provides various stages to managing the UI of application and during transition system always notifies you via a lifecycle callback method. There are 7 android activity lifecycle methods like onCreate, onStart, onResume, onPause, onStop, onDestroy, and onRestart.
The activity lifecycle events to ensure smooth transitions of UI and a responsive user experience in your apps.
Let's understand first with android activity lifecycle diagram. How activity lifecycle works internally?
OnCreate() -
The onCreate() method is the first method of activity lifecycle and it's called when an Activity is created first time. The use of onCreate() such as initializing UI components, variables, and implementing any necessary tasks setup before the Activity becomes visible to the user.
OnStart() -
The onStart() method is a callback method called when an Activity becomes visible to the user.
It's used to register listeners, start background tasks, or perform other tasks that need to be execute each time of the activity starts.OnResume() -
The onResume() method is called when the Activity visible in the foreground state and ready to interacting with the user.
It's generally used to resume tasks that were paused or stopped when the application was not in the foreground state, such as animations task or sensor data updates.
OnPause() -
The onPause() method is a callback method called when an Activity is no longer visible in the foreground state but is still partially visible to the user.
It's generally used to pause the tasks execution that should not continue running when the application is not in visible to user or its suitable for save and unsave data.
OnStop() -
The onStop() method is a callback method called when an activity is no longer visible to user.
It's generally used for cleanup tasks, such as like unregister listeners or receivers, stopping background tasks or releasing resources.
OnDestroy() -
The onDestroy() method is a last callback method called when an activity is completely destroyed. Suppose If the user doesn't return back to the activity for a longer time then , onStop() method called and then onDestroy() called.
It's generally used for final cleanup the tasks, such as like releasing resources, unregister listeners or receivers or stopping background services.
OnRestart() -
The onRestart() method is a callback method called when an Activity is stopped and then restarted.
Its used for restart the Activity that means after activity stopped it's prepare to become visible again to the user.
Ques-2: From Activity A, then go to Activity B, then go back to Activity A, What Activity Lifecycle method will be called during this Scenario Explain?
Ans-2: Let's understand the scenario.
- If user come to Activity A :-
onCreate() -> onStart() -> onResume() in Activity A
- If user press navigation button for go from Activity A to Activity B :-
onPause() in Activity A
onCreate() -> onStart() -> onResume() in Activity B
onStop() in Activity A
- If user press back button on Activity B :-
onPause() in Activity B
onRestart() -> onStart() -> onResume() in Activity A
onStop() -> onDestroy() in Activity B
Ques-3: What happens if the user returns to the Activity again after being stopped, What Activity Lifecycle method will be called during this Scenario Explain?
Ans-3:
- If the user comes back again to the activity before it’s destroyed, then the activity is restarted via the onRestart() method.
onRestart() -> onStart() -> onResume() - This lifecycle will be called during this scenario.
- If the user comes back again to the activity after its destroyed, then the activity is created again.
onCreate() -> onStart() -> onResume() - This lifecycle will be called during this scenario.
Ques-4: If the user press home button while interacting with Activity (Background State) and If user return again from home screen to Application (Foreground State), What Activity Lifecycle method will be called during this Scenario Explain?
Ans-4:
- If user press home button while interacting with Activity (Background State)
onPause() -> onStop() - This lifecycle will be called during this scenario.
- If user return again from home screen to Application (Foreground State)
onRestart() -> onStart() -> onResume() - This lifecycle will be called during this scenario.
Ques-5: If you have an Activity and you open a dialog in that Activity, which Activity lifecycle method will be called in that scenario?
Ans-5: onPause()
Ques-6: Which Activity lifecycle method will be called during Refresh Activity and Configuration or Orientation changes?
Ans-6: onPause() -> onStop() -> onDestroy() -> onCreate() -> onStart() -> onResume()
Ques-7: How do you handle (Save or Restore) data while configuration changes in the Android Activity Lifecycle?
Ans-7: During Configuration changes, like screen orientation changes or language changes, can lead to destroyed and recreate of the Activity. To handle the data while configuration changes, you can save data inside `onSaveInstanceState()` method and then restore data inside `onRestoreInstanceState()` method.
onSavedInstanceState() -> onPause() -> onStop() -> onCreate() -> onRestoreInstanceState() -> onResume() - This lifecycle will be called during this scenario.
Ques-8: When will call onCreate() and onDestroy() method, and how many times it will be called?
Ans-8: onCreate() and onDestroy() method will be called two times:
- when activity is created on the first time and destroy the activity
- when user rotates device then both method gets called again.
Ques-9: What is the role of `onConfigurationChanged()` method in the Android Activity Lifecycle?
Ans-9: The `onConfigurationChanged()` method is called when the configuration changes happened in device, like language changes or screen orientation changes. It allows you to handle these changes without having to recreate the whole Activity.
Ques-10: Can we use an Activity without UI?
Ans-10: Yes we can use because Android provides a theme for this requirement and with the help of dynamically or programmatically create UI design without using xml.
Reference Site
here you can learn more about Android Activity Lifecycle Interview Questions
Conclusion
In this blog, I have covered all most important Android Activity Lifecycle Interview Questions with Example in 2024. You can easily learn and prepare yourself for the interview.