LiveData update values when field of object change - android-databinding

Question

Today I'm trying to use a LiveData (MutableLiveData) object to have some dynamics values. (in MVVM pattern)
I used a model object like this:
public class Object {
private String name;
private float internalvalue;
private float in1;
private float out1;
private float out2;
public Object(String name, float internalvalue){
this.name = name;
this.internalvalue = internalvalue;
}
public float getOut1(){
return this.out1;
}
public float getOut2(){
return this.out2;
}
public void setIn1(float in1){
this.in1 = in1;
}
private void performSomething(float internalvalue, float in1){
SubClassSingleton.performSomething(internalvalue, in1, new SubClassSingletonListener() {
#Override
public void onSuccess(float out1, float out2){
this.out1 = out1;
this.out2 = out2;
}
});
}
}
I use a ViewModel like this:
public class MainViewModel {
public MutableLiveData<Object> obj;
public MainViewModel(){
this.obj = new MutableLiveData<>();
this.obj.postValue(new Object("Name", 50.0f);
}
}
In MainFragment:
public class MainFragment extends Fragment {
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
MainViewModel viewModel = ViewModelProviders.of(this).get(MainViewModel.class);
MainFragmentBinding binding = MainFragmentBinding.inflate(getLayoutInflater());
binding.setViewModel(viewModel);
binding.setLifecycleOwner(this);
return binding.getRoot();
}
}
And in View:
<layout ...
<data>
<variable
name="viewModel"
type="app.example.MainViewModel"/>
</data>
<LinearLayout
...>
<EditText
android:text="#={viewModel.obj.in1}"
.../>
<TextView
android:text="#{viewModel.obj.out1}"
.../>
<TextView
android:text="#{viewModel.obj.out2}"
.../>
</LinearLayout>
</layout>
I'd like to update my view when the values (out1, out2) of my model are updated (when the calculation is performed).
How can I do this ?

Answer 1

Try this:
You need to make your model class extend BaseObservable.
public class Object extends BaseObservable {
private String name;
private float internalvalue;
private float in1;
private float out1;
private float out2;
public Object(String name, float internalvalue) {
this.name = name;
this.internalvalue = internalvalue;
}
public float getOut1() {
return this.out1;
}
public void setOut1(float out1) {
this.out1 = out1;
notifyChange();
}
public float getOut2() {
return this.out2;
}
public void setOut2(float out2) {
this.out2 = out2;
notifyChange();
}
public void setIn1(float in1) {
this.in1 = in1;
}
private void performSomething(float internalvalue, float in1) {
SubClassSingleton.performSomething(internalvalue, in1, new SubClassSingletonListener() {
#Override
public void onSuccess(float out1, float out2) {
setOut1(out1);
setOut2(out2);
}
});
}
}
And in View, you cannot bind float directly to view. It has to be string, so bind like this:
<layout ...
<data>
<variable
name="viewModel"
type="app.example.MainViewModel"/>
</data>
<LinearLayout
...>
<EditText
android:text='#={""+viewModel.obj.in1}'
.../>
<TextView
android:text='#{""+viewModel.obj.out1}'
.../>
<TextView
android:text='#{""+viewModel.obj.out2}'
.../>
</LinearLayout>
</layout>