37.3 Adding the Observer

Observers are added to lifecycle owners via calls to the addObserver() method of the owner’s Lifecycle object, a reference to which is obtained via a call to the getLifecycle() method. Edit the MainFragment.java class file and add code to the onActivityCreated() method to add the observer:

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import com.ebookfrenzy.lifecycledemo.DemoObserver;

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@Override

public void onActivityCreated(@Nullable Bundle savedInstanceState) {

    super.onActivityCreated(savedInstanceState);

    mViewModel = ViewModelProviders.of(this).get(MainViewModel.class);

 

    getLifecycle().addObserver(new DemoObserver());

}

With the observer class created and added to the lifecycle owner’s Lifecycle object, the app is ready to be tested.