Android - no_image

1. Bundle savedInstanceState is a reference to the Bundle object that is passed to the onCreate() in an Activity. Activities have capability to restore themselves to a previous state using the stored in the Bundle.

2. First time the bundle object is always null. If some data is stored in the bundle object during the Activity lifecycle and Activity is recreated due to rotation then the bundle object will be non-null.

   During the Activity Lifecycle save the data in onSaveInstanceState()

   
    int scrolledPosition = 0;  
   	  
    @Override  
    public void onSaveInstanceState(Bundle outState) {  
        super.onSaveInstanceState(outState);  
        outState.putInt("scrolled_position",scrolledPosition);  
    }
   
   

   After the orientation when the Activity is recreated and onCreate() is called

      int scrolledPosition = 0;
   	  
      @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        if(savedInstanceState == null){  
            scrolledPosition = 0;  
        }else{  
            scrolledPosition = savedInstanceState.getInt("scrolled_position",0);  
        }  
    }
   

   There is an alternative way of restoring state , onRestoreInstanceState() which system calls after onStart(). The system calls onRestoreInstanceState() only if there is a state to restore. So there is no need to check if bundle object is null.

      int scrolledPosition = 0;
   	  
      public void onRestoreInstanceState(Bundle savedInstanceState) {  
         // Always call the superclass so it can restore the view hierarchy    
         super.onRestoreInstanceState(savedInstanceState);  
     
        // Restore state members from saved instance    
         scrolledPosition = savedInstanceState.getInt("scrolled_position",0);  
    }
   

   Note: Always call the superclass implementation of onRestoreInstanceState()so the default implementation can restore the state of the view hierarchy.

   What kind of data should be stored in bundle object

   1. User selections

   2. Scroll positions

   3. User submitted data

   What kind of data shouldn’t be stored in bundle object

   1. Bitmap

   2. File

   3. Big Model classes(POJO)

   Reference Link:

   https://developer.android.com/guide/components/activities/activity-lifecycle#restore-activity-ui-state-using-saved-instance-state

credit goes to @swayangjit