Android Developer Activity

Android Activity

Android activity lifecycle

An activity is a single screen in android. It is like a window or frame of Java. By the help of activity, you can place all your UI components or widgets in a single screen. The 7 lifecycle method of Activity describes how activity will behave at different states. Android Training good career in further

Android Activity Lifecycle Example

It provides details about the invocation of life cycle methods of activity. In this example, we are displaying the content on the logcat.

File: MainActivity.java

1.    package example.javatpoint.com.activitylifecycle;  

2.      

3.    import android.app.Activity;  

4.    import android.os.Bundle;  

5.    import android.util.Log;  

6.      

7.    public class MainActivity extends Activity {  

8.      

9.        @Override  

10.     protected void onCreate(Bundle savedInstanceState) {  

11.         super.onCreate(savedInstanceState);  

12.         setContentView(R.layout.activity_main);  

13.         Log.d("lifecycle","onCreate invoked");  

14.     }  

15.     @Override  

16.     protected void onStart() {  

17.         super.onStart();  

18.         Log.d("lifecycle","onStart invoked");  

19.     }  

20.     @Override  

21.     protected void onResume() {  

22.         super.onResume();  

23.         Log.d("lifecycle","onResume invoked");  

24.     }  

25.     @Override  

26.     protected void onPause() {  

27.         super.onPause();  

28.         Log.d("lifecycle","onPause invoked");  

29.     }  

30.     @Override  

31.     protected void onStop() {  

32.         super.onStop();  

33.         Log.d("lifecycle","onStop invoked");  

34.     }  

35.     @Override  

36.     protected void onRestart() {  

37.         super.onRestart();  

38.         Log.d("lifecycle","onRestart invoked");  

39.     }  

40.     @Override  

41.     protected void onDestroy() {  

42.         super.onDestroy();  

43.         Log.d("lifecycle","onDestroy invoked");  

44.     }  

45. }  

Output:

You will not see any output on the emulator or device. You need to open logcat.

Sr.No	Callback & Description
1	onCreate() This is the first callback and called when the activity is first created.
2	onStart() This callback is called when the activity becomes visible to the user.
3	onResume() This is called when the user starts interacting with the application.
4	onPause() The paused activity does not receive user input and cannot execute any code and called when the current activity is being paused and the previous activity is being resumed.
5	onStop() This callback is called when the activity is no longer visible.
6	onDestroy() This callback is called before the activity is destroyed by the system.
7	onRestart() This callback is called when the activity restarts after stopping it.

Conclusion

Android Career

Android class works in the same way. By extending the Activity class which haveonCreate(Bundle bundle) method in which meaningful code is written and to execute that code in the defined activity, use the super keyword with the method onCreate()like super.onCreate(bundle) 

High-Demand for App Developers

By 2024, there will be 48,500 additional tech jobs. ... Become an Android Developerif you're keen on a flexible and stimulating career, which is in high demand. HyperionDev offers a 6-month, part-time Mobile Developer Bootcamp aligned to the Google Associate Android Developer certification.