We Keep Coding

Nested Child Fragment does NOT observe LiveData properly

I have a Parent Fragment, called WaterFountainFragment, that has a nested Fragment progamatically inflated inside a FrameLayout that is dependant of an user's choice in a RadioGroup. If the user chooses one option, it inflates one Child and, when chosen the other option, it inflates another child (in the name of being the most concise as possible, I'll only list one of those child fragments, since the problem happens in both of them).
The user enters the data he wants and save it on the database, using LiveData and Room dependencies to do so. However, if the user wants to go back and check which data was saved in an specific entry, then we start to face trouble.
The problem is, the saved data is shown in the Parent Fragment but, unfortunately, it does NOT load inside the child fragment nested on it.
First, let me show the parent class in which I think everything is working normally:
WaterFountainFragment Class
public class WaterFountainFragment extends Fragment {
(...)
#Override
public void onStart() {
super.onStart();
//modelEntry is a ViewModel, which class ViewModelEntry will be shown later
modelEntry = new ViewModelEntry(requireActivity().getApplication());
//The ID of an entry is sent to this fragment through a bundle (via setArgument());
if (waterFountainBundle.getInt(FOUNTAIN_ID) > 0) {
//getOneWaterFountain is a method inside modelEntry to obtain an entry from the database through
//LiveData and Room
modelEntry.getOneWaterFountain(waterFountainBundle.getInt(FOUNTAIN_ID))
.observe(getViewLifecycleOwner(), this::loadFountainInfo);
}
}
//this is a RadioGroup Listener where it inflates the specific child fragment inside a FrameLayout
public void typeFountainListener(RadioGroup group, int checkedID) {
int index = getCheckedFountainType(group);
switch (index) {
case 0:
getChildFragmentManager().beginTransaction()
.replace(R.id.water_fountain_info, new WaterFountainSpoutFragment()).commit();
break;
case 1:
getChildFragmentManager().beginTransaction()
.replace(R.id.water_fountain_info, new WaterFountainOtherFragment()).commit();
break;
default:
break;
}
}
//method to fill all fields inside this fragment
private void loadFountainInfo(WaterFountainEntry waterFountain) {
fountainLocationValue.setText(waterFountain.getFountainLocation());
typeWaterFountain
.check(typeWaterFountain.getChildAt(waterFountain.getTypeWaterFountain()).getId());
if (waterFountain.getFountainTypeObs() != null)
fountainTypeObsValue.setText(waterFountain.getFountainTypeObs());
//At this point the RadioGroupListener is active already and, when checking a RadioButton, it will
//inflate the child and send a fragmentResult to this child fragment
getChildFragmentManager()
.setFragmentResult(InspectionActivity.LOAD_CHILD_DATA, waterFountainBundle);
}
}
Now we have one of the 2 nested child fragments that are inflated:
WaterFountainSpoutFragment Class
public class WaterFountainSpoutFragment extends Fragment {
#Override
public void onStart() {
super.onStart();
//the ViewModel is instantiated here with the same name and method as the
//one instantiated in the ParentFragment
modelEntry = new ViewModelEntry(requireActivity().getApplication());
//FragmentResultListener is active and it does recieve the signal from the parent Fragment.
getParentFragmentManager()
.setFragmentResultListener(InspectionActivity.LOAD_CHILD_DATA, this, (key, bundle) ->
//However, inside this resultListener, this observer seems to not be triggered
modelEntry.getOneWaterFountain(bundle.getInt(WaterFountainFragment.FOUNTAIN_ID))
.observe(getViewLifecycleOwner(), this::loadSpoutFountainData)
);
}
}
Here we have the ViewModel, the repository and the Dao classes/interfaces that were used on those 2 classes above
ViewModelEntry class
public class ViewModelEntry extends AndroidViewModel {
public ViewModelEntry(#NonNull Application application) {
super(application);
repository = new ReportRepository(application);
allEntries = repository.getAllSchoolEntries();
}
public LiveData<WaterFountainEntry> getOneWaterFountain(int waterFountainID) {
return repository.getOneWaterFountain(waterFountainID);
}
}
ReportRepository Class
public class ReportRepository {
private ReportDatabase db;
private final WaterFountainDao waterFountainDao;
public ReportRepository(Application application) {
waterFountainDao = db.waterFountainDao();
}
public LiveData<WaterFountainEntry> getOneWaterFountain(int waterFountainID) {
return waterFountainDao.getOneWaterFountain(waterFountainID);
}
}
WaterFountainDao Interface
#Dao
public interface WaterFountainDao {
#Query("SELECT * FROM WaterFountainEntry WHERE waterFountainID == :waterFountain")
LiveData<WaterFountainEntry> getOneWaterFountain(int waterFountain);
}
What I know/tested so far
Using a Toast, I confirmed that getParentFragmentManager().setFragmentResultListener() is being called. Even more so, the bundle recieve the right data.
If I use the modelEntry.getOneWaterFountain(bundle.getInt(WaterFountainFragment.FOUNTAIN_ID)).observe(getViewLifecycleOwner(), this::loadSpoutFountainData) outside the resultListener, it does load the correct data into the child Fragment fields.
The data entered by the user IS being stored in the database. I confirmed that using the Database Inspector, so it is not a case where "the data is not being stored properly, hence why is not loading".
I use the same method in other Parent/Child Fragments, using the same format of resultListener and it DOES load the data.
Using another method for creating this ViewModel, like modelEntry = new ViewModelProvider.AndroidViewModelFactory(requireActivity().getApplication()).create(ViewModelEntry.class); in both parent and child fragments results in the same problem
What I SUPPOSE it might be the case
I have wondered that it might be a situation where I am choosing the wrong LyfecycleOwner but I don't know if that is the case, mainly because of what I put on item 4.
Any help would be greatly appreciated.

Is there an alternative in Android Java for Message sendToTarget to access View in inner class of an activity?

i have an activity where i have a text view. I am also using an sdk which has some events.
Within on of these events i need to display some data at the TextView.
The events are in an external class and i got them via some interfaces.
The interfaces iam implementing within the Activity.
I am using Handler and Message to set the text into the TextView within the implementation of the interface.
I would like to know if there is another way to set the text within the the interfaces except Handler and Message.
Here is that code:
public class MyActivity extends AppCompatActivity {
private TextView nameTextView;
// some code
// implementing interfaces of external class
Service.ServiceEvents events = new Service.ServiceEvents() {
#Override
public void onSomeEvent(String name) {
nameTextView.setText(name); // not working
Message m = myHandler.obtainMessage(0, nameTextView);
m.sendToTarget();
}
Handler myHandler = new Handler(Looper.getMainLooper()) {
#Override
public void handleMessage(Message message) {
String s = message.obj.toString();
nameTextView.setText(s);
}
};
}
} // end of activity
Is there another way to set the text in the TextView?
Please Help.

What to use
You can do it by using an interface.
How to implement
Create a new interface and give it a name whatever u like.(Here it is SampleInterface).
Add some void methods to like this
void onSomeEvent(String name);
Create a object of it in the class where you get the data from the sdk and add this listener in its constructor. Something like this
public YourJavaClassName(SampleInterface sampleInterface) {
this.sampleInterface= sampleInterface;
}
When you receive an update in the sdk, you can call it like this
void onDataReceived(String name){// I don't know how you get the value from the sdk so I wrote this
sampleInterface.onSomeEvent(name);
}
You are done with implementing it in the sdk receiver class. Now you need to add to the main activity to receive and update data.
Create the object of the class where you receive the data from the sdk.Like this
MySDKReceiverClass mysdkreceiverclass;
mysdkreceiverclass = new MySDKReceiverClass(this);
Implement the interface in the activity and there you ge the values and you can set it in the textview.
Note: You need not add any runnable or handler or anything.Whenever there is a value change, the listener is called and the value is set.

Vaadin: How to add 3 nested layouts

I'm having issues with my UI in vaadin at the moment. I have my views connected with RouterLayout like this:
-AppView (the main UI) | url: /
--OperationsView (a nested layout inside a container in AppView) | url: /operations
---Operation1View (a nested layout inside a container in OperationsView) | url: /operation1 <-
This isn't working
My declarations before any class are:
AppView declaration
#Route(value = AppView.ROUTE)
OperationsView declaration
#Route(value = OperationsView.ROUTE, layout = AppView.class)
Operation1View declaration
#Route(value = Operation1View.ROUTE, layout = OperationsView.class)
The problem is the third layout doesn't display correctly. It takes the whole page when accesed and mess up everything in the UI when going to another page. Shouldn't the url be: /operations/operation1 and not /operation1? However I can't get it to work correctly. Am I missing something? Or having 3 nested layouts is not possible with vaadin?
A possible solution (?): Should I dismiss the third nested layout and add methods in the second layout to remove the contents in the container and display the items I want? I really don't care about url navigation in this one. This is the last thing I can come up with.
Thanks in advance

Or having 3 nested layouts is not possible with vaadin?
It's possible. But are you implementing a RouterLayoutin both OperationsView and AppView classes?
Take a look into example here: Multiple parent layouts with #ParentLayout. It has a set-up pretty close to yours.
public class MainLayout extends Div implements RouterLayout {
}
#ParentLayout(MainLayout.class)
public class MenuBar extends Div implements RouterLayout {
public MenuBar() {
addMenuElement(TutorialView.class, "Tutorial");
addMenuElement(IconsView.class, "Icons");
}
private void addMenuElement(Class<? extends Component> navigationTarget,
String name) {
// implementation omitted
}
}
#Route(value = "tutorial", layout = MenuBar.class)
public class TutorialView extends Div {
}
#Route(value="icons", layout = MenuBar.class)
public class IconsView extends Div {
}
Shouldn't the url be: /operations/operation1 and not /operation1?
No, as in your #Router annotation you have specified that it's operation1. By specifying a layout you are defining the DOM structure, not the navigation route.From docs :
Sets the parent component for the route target component.When navigating between components that use the same layout, the same component instance is reused. Default layout target is the UI, but the layout should not be a custom UI as UI is a special class used to know where the route stack ends and no parent layouts should be involved.
All layout stacks will be appended to the UI as it represents the Body element.
BUT If you want it to be operation\operation1, you should use a #RoutePrefix instead ParentLayout Route Control
It takes the whole page when accesed and mess up everything in the UI when going to another page
Could you show a screenshot or add some details how it messes up?
Edit:
It's actually turned out to be harder to implement than I anticipated, but this seems to work:
MainView.java
#Route("")
public class MainView extends VerticalLayout implements RouterLayout {
....
OperationsView.java
//This is needed if you want "operations" to be accessible on its own
#Route(value = "operations",layout = MainView.class)
#ParentLayout(MainView.class)
public class OperationsView extends VerticalLayout implements RouterLayout {
Div content=new Div();
public OperationsView(){
System.out.println("operations view");
add(new Label("operations view"));
add(content);
}
}
Operation1View.java
#Route(value="operation1",layout = OperationsView.class)
#RoutePrefix("operations")
public class Operation1View extends VerticalLayout {
public Operation1View(){
add(new Label("Operations view"));
}
}

Spring(-Boot) & Vaadin - Set default-view in Vaadin navigator

first of all I have here a simple UI which has a addMenueItem() Method. This method gets a view-id and adds a button to the menue and tells the navigator from Vaadin to navigate to it on click:
.........
#PostConstruct
private void initPage() {
navigator.addProvider(viewProvider);
contentLayout.setSizeFull();
}
protected void addMenuItem(final String viewId) {
final String postfix;
if (viewId == null || viewId.trim().isEmpty()) {
postfix = "";
} else {
postfix = "." + viewId;
}
final String name = messageByLocaleService.getMessage(I18N_PREFIX + postfix);
menue.addItem(name, menueCommand -> getUI().getNavigator().navigateTo(viewId));
}
.........
So I'm adding some views from my MainUI like:
addMenuItem(DefaultView.VIEW_ID);
The Spring url based view resolver calls the now the id from the value of 'DefaultView.VIEW_ID'. Now I'm looking for a good solution to map a given view-id not only to ' /VIEW-ID ' but also to the application root path --> ' / '.
How can I tell Spring that this special ViewID is also the root or an synonym for /VIEW-ID ?
For sure there is a possibility to hard-code this in some kind of xml-file of Tomcat or something, but i would like to do so dynamically.
Thanks in advance
PS: I'm very new to spring and this kind of stuff, courtesy please :D

The navigator and the URI fragment go hand in hand. The root path does not have any URI fragment therefore the navigator does not know where to navigate when the URL is called.
You can solve that problem in your UI class like this:
#SpringUI
public class MainUI extends UI {
#Autowired
SpringViewProvider viewProvider;
#Override
protected void init(VaadinRequest request){
Navigator navigator = new Navigator(this,this);
navigator.addProvider(viewProvider);
this.setNavigator(navigator);
// Set default view
NavigationStateManager stateManager = new Navigator.UriFragmentManager(getPage());
stateManager.setState(DefaultView.VIEW_ID);
}
}
Explanation:
Most of the stuff should be well known already because these are basics that can be read in several tutorials, e.g.: III Views and Navigation with Vaadin Spring
In short:
You use the #SpringUI annotation, which by default maps to /, to register a new UI
You autowire the SpringViewProvider which automatically registers your views.
You initialize the navigator.
To set the default view you simply initialize the NavigationStateManager which sets the URI fragment. Once the init method completes the UI class calles the Navigator.navigateTo() method with the current state of the NavigationStateManager.
NOTE: You might find something in the net like:
navigator.navigateTo(DefaultView.VIEW_ID);
If you use this in the init method of the UI your navigator is called twice.

GWT-Platform revealing presenters together

Hey so I am just learning the gwtp framework and I have come across a bit of a dilemma. I have a LayoutPresenter at the top level that has a main content slot and menu content slot and I am trying to find a way to bind my presenters for each slot together if possible so when the main content is revealed it will automatically show the correct side menu. Currently I have a static boolean in the Menu's Presenter that get updated onReveal and onHide. I can then check if the menu is visible when the main content is revealed and if not I reveal it.
public class MenuPresenter extends Presenter<MenuPresenter.MyView, MenuPresenter.MyProxy> {
private static boolean hidden = true;
...
#Override
protected void revealInParent() {
RevealContentEvent.fire(this, LayoutPresenter.SIDE, this);
}
#Override
protected void onReveal(){
super.onReveal();
hidden = false;
}
#Override
protected void onHide(){
super.onHide();
hidden = true;
}
public static boolean isHidden(){
return hidden;
}
}
Then in The main content Presenter:
public class ContentPresenter extends
Presenter<ContentPresenter.MyView, ContentPresenter.MyProxy> {
...
private final DispatchAsync dispather;
private final PlaceManager placeManager;
#Inject
public PhoneCallPresenter(final EventBus eventBus, final MyView view, final MyProxy proxy, final DispatchAsync dispatcher, final PlaceManager placeManager) {
super(eventBus, view, proxy);
this.dispather = dispatcher;
this.placeManager = placeManager;
}
#Override
protected void revealInParent() {
RevealContentEvent.fire(this, LayoutPresenter.CONTENT, this);
}
#Override
protected void onReveal() {
super.onReveal();
if (MenuPresenter.isHidden()){
placeManager.revealPlace(new PlaceRequest(NameTokens.menu));
}
}
}

As far as I understood the question, you want to have different side-menus for different main contents.
In this case there are two solutions:
Treat the menu as a normal Presenter (you will probably have multiple of them for each main content type). You just need to annotate the corresponding MenuPresenter with the same history token as your main content Presenter. So for the above example you would have a PhoneCallMenuPresenter that is annotated with the same history token as your PhoneCallPresenter. When you navigate to /phonecall (or whatever your history token is), both PhoneCallPresenter and PhoneCallMenuPresenter will be revealed automatically . (you don't have to do anything).
In case you want to have only one MenuPresenter and put the logic what to display in the Presenter itself, I would recommend to use a PresenterWidget instead of a normal Presenter. The MenuPresenterWidget will be injected into the LayoutPresenter and will be added to the LayoutPresenter.SIDE slot. You can define a setter for the MenuPresenterWidget to specify which main content is currently displayed (the setter will be called from the LayoutPresenter or you can override the onReset() method and check the current place request and decide what to display in the menu.
For solution 1 you have to have one MenuPresenter for each main content Presenter and potentially many code lines will be redundant (you could create a base MenuPresenter and derive from it). So in case you have a lot of business logic in the side-menu which is quite different from main content to main content, I would go with solution 1. In case you only display different links the overhead of creating a MenuPresenter per main content Presenter might be to high and I would go with solution 2 and create only one MenuPresenterWidget for all main content types and always show it.