I am trying to write an example application using the components of the Android architecture, but even after several days of work, I could not get it to work. This gives me the above exception.
Life Cycle Owner: -
public class MainActivity extends LifecycleActivity {
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textView = findViewById(R.id.tv_user);
PostViewModel viewModel = ViewModelProviders.of(this).get(PostViewModel.class);
viewModel.loadPosts();
viewModel.getPost().observe(this, new Observer<Post>() {
@Override
public void onChanged(@Nullable Post post) {
if(post != null) {
textView.setText(post.toString());
}
}
});
}
}
ViewModel: -
public class PostViewModel extends ViewModel {
private MediatorLiveData<Post> post;
private PostRepository postRepo;
PostViewModel() {
post = new MediatorLiveData<>();
postRepo = new PostRepository();
}
public LiveData<Post> loadPosts() {
post.addSource(postRepo.getPost(),
post -> this.post.setValue(post)
);
return post;
}
@NonNull
public LiveData<Post> getPost() {
return post;
}
}
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