ViewModel in Android Application

- UI controller like activities / fragments primary intented to display data, react to user actions, or handling OS communication, etc.

- ViewModel will separate view data handling and UI controller logic

- ViewModel scope is available from Activity onCreate() to onDestroy()

- ViewModel won't loss data if our Activity destroys or re-created due to configuration changes by OS

******without ViewModel******

1) Create activity with TextView and Button

2) Declare counter variable in activity and display with TextView

3) on button click increment count and display updated value with textview

4) run and test the output by incrementing counter 4-5 times

- also change orientation of device then it will loss the value

******with ViewModel******

1) Create class by extending ViewModel class

2) declare MutableLiveData Integer counter instance

3) create getter and setter method for counter instance

def lifecycle_version = "2.3.1"
// ViewModel
implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version"
// LiveData
implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"

4) create instance of ViewModel inside Activity as below

MyViewModel model = new ViewModelProvider(this).get(MyViewModel.class);

5) call counter getter method and also implement observe method with livedata and set value with textview

6) run the app and check the output by changing orientation

--if you any query then you can comment on comment box.

#viewmodel #android #coding #example