Can’t access viewmodels from detached fragment

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In Android, a detached fragment is a fragment that is no longer associated with its activity. This means that it is not currently visible on the screen and does not have access to the activity’s view hierarchy.

When a fragment is detached from its activity, its lifecycle methods (such as onCreate, onCreateView, etc.) are not called. Therefore, the fragment’s view and viewmodel are not available.

If you need to access the viewmodel from a detached fragment, there are a few options:

  1. Reattach the fragment to its activity: If you want to regain access to the fragment’s view and viewmodel, you can reattach the fragment to its activity. This can be done using the FragmentManager and the attach method. Here’s an example:
        
Fragment fragment = fragmentManager.findFragmentById(R.id.fragment_container);
fragmentManager.beginTransaction().attach(fragment).commit();
  1. Use a shared viewmodel: If you have multiple fragments that need to access the same data, you can use a shared viewmodel. This can be achieved by using the ViewModelProviders class to get the viewmodel from the activity, and then sharing it with the fragments. Here’s an example:
        
SharedViewModel sharedViewModel = ViewModelProviders.of(getActivity()).get(SharedViewModel.class);

Then, each fragment can access the shared viewmodel using:

        
sharedViewModel.getData().observe(this, new Observer<Data>() {
    @Override
    public void onChanged(Data data) {
        // Update UI with the new data
    }
});
  1. Use arguments or savedInstanceState: Another option is to pass the necessary data to the fragment using arguments or saving it in the fragment’s savedInstanceState. This way, when the fragment is reattached to the activity, it can retrieve the data and update its viewmodel accordingly. Here’s an example:
        
Bundle args = new Bundle();
args.putString("data", "example data");
fragment.setArguments(args);

Then, in the fragment’s onCreateView method:

        
Bundle args = getArguments();
if (args != null) {
    String data = args.getString("data");
    // Update viewmodel with the data
}

These are some approaches you can take when you need to access viewmodels from a detached fragment. The choice depends on your specific requirements and the architecture of your app.

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