Initializing ViewModel in fragment Android java

问题

I am trying to initialize my viewmodel object in the FirstFragment.java file of BasicActivity. All theses four codes are failed. The documentation could not help me much.

mViewModel = new ViewModelProvider(this).get(MyViewModel.class);
mViewModel = new ViewModelProvider(requireActivity()).get(MyViewModel.class);
mViewModel = new ViewModelProvider(getActivity()).get(MyViewModel.class);
mViewModel = new ViewModelProvider(FirstFragment.class).get(MyViewModel.class);

On the other hand, public ViewModelProvider(@NonNull ViewModelStoreOwner owner) ViewModelProvider is taking ViewModelStoreOwner as its parameter and in the FragmentActivity.java ViewModelStore getViewModelStore() method of ViewModelStore interface is implemented may be in a factory pattern.

@NonNull
        @Override
        public ViewModelStore getViewModelStore() {
            return FragmentActivity.this.getViewModelStore();
        }

Help me initializing ViewModel

回答1:

Initializing your viewModel goes like:

if you are using

implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'

and Intialize your viewModel

viewModel = ViewModelProviders.of(this,viewModelFactory).get(MyViewModel.class);

but it's deprecated now. So update the dependency to:

implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'

and initial your viewModel as follow:

viewModel = new ViewModelProvider(this,viewModelFactory).get(MyViewModel.class);

viewModelFactory is optional.

来源：https://stackoverflow.com/questions/61395560/initializing-viewmodel-in-fragment-android-java

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