Why does my activity doesn't see an observed object change?

Question

I\'m new to Android development and i am trying to understand Live Data with MVVM architecture. I am trying to make the main activity recognize when there is a change in an obje

Answer 1

Solution by OP.

As Neha Rathore suggested this is the solution that works for me:

in the view Model:

public void login(String userName , String hashedPassword) {
    usersRepository.login(userName, hashedPassword, new Callback<String>() {
        @Override
        public void onResponse(Call<String> call, Response<String> response) {
            loggedInUser.setValue(response.body());
        }

        @Override
        public void onFailure(Call<String> call, Throwable t) {
            loggedInUser.setValue(null);
        }
    });
}

and in the Repository:

public void login(String username, String hashedPassword,@Nullable final Callback<String> callback){
    final MutableLiveData<String> loggedInUser = new MutableLiveData<>();
    User user = new User(username,hashedPassword);

    usersRepositoryApi.login(user).enqueue(new Callback<String>() {
        @Override
        public void onResponse(Call<String> call, Response<String> response) {
            if (response.isSuccessful()) {
                callback.onResponse(call,response);
            }
        }

        @Override
        public void onFailure(Call<String> call, Throwable t) {
            callback.onFailure(call,t);
        }
    });
}

Answer 2

here your problem is with repository code inside repository you are creating new object of mutable live data and observing different one.

Interface Callback{
    onSuccess(String response)
    onError(String error)
}

public void login(String username , String hashedPassword,Callback callback){
    final MutableLiveData<String> loggedInUser = new MutableLiveData<>();
    User user = new User(username,hashedPassword);

    usersRepositoryApi.login(user).enqueue(new Callback<String>() {
        @Override
        public void onResponse(Call<String> call, Response<String> response) {
            if (response.isSuccessful()) {
                callback.onSuccess(response.body());
            }
        }

        @Override
        public void onFailure(Call<String> call, Throwable t) {
            callback.onError(null);
        }
    });
}

//login method of your viewmodel 
public void login(String userName , String hashedPassword) {
     usersRepository.login(userName, hashedPassword,new Callback(){
          void onSuccess(String responsebody){
               loggedInUser.setValue(responsebody);
          }

          void onError(String error){
               loggedInUser.setValue(responsebody);
          }
     });
}

Answer 3

In your repository, try changing this part:

loggedInUser.setValue(response.body());

to postValue function. like that:

loggedInUser.postValue(response.body());