How to use data-binding with Fragment
I'm trying to follow data-binding example from official google doc https://developer.android.com/tools/data-binding/guide.html
except that I'm trying to apply data-biding to a fragment, not an activity.
the error I'm currently getting when compiling is
Error:(37, 27) No resource type specified (at 'text' with value '@{marsdata.martianSols}.
onCreate
for fragment looks like this:
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MartianDataBinding binding = MartianDataBinding.inflate(getActivity().getLayoutInflater());
binding.setMarsdata(this);
}
onCreateView
for fragment looks like this:
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.martian_data, container, false);
}
and parts of my layout file for fragment looks like this:
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="marsdata"
type="uk.co.darkruby.app.myapp.MarsDataProvider" />
</data>
...
<TextView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:text="@{marsdata.martianSols}"
/>
</RelativeLayout>
</layout>
my suspicion is that MartianDataBinding
doesn't know which layout file it's supposed to be bound with - hence the error. Any suggestions?
The data binding implementation must be in the onCreateView
method of the fragment, delete any data Binding that exist in your OnCreate
method,
your onCreateView
should look like this:
public View onCreateView(LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
MartianDataBinding binding = DataBindingUtil.inflate(
inflater, R.layout.martian_data, container, false);
View view = binding.getRoot();
//here data must be an instance of the class MarsDataProvider
binding.setMarsdata(data);
return view;
}
You are actually encouraged to use the inflate
method of your generated Binding and not the DataBindingUtil:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
MainFragmentBinding binding = MainFragmentBinding.inflate(inflater, container, false);
//set variables in Binding
return binding.getRoot();
}
Docs for DataBindingUtil.inflate():
Use this version only if layoutId is unknown in advance. Otherwise, use the generated Binding's inflate method to ensure type-safe inflation.
Even the other answers may work well, but I want tell best approach.
Use Binding class's inflate
as recommended in Android Documentation.
One option is to inflate by DataBindingUtil
but when only you don't know have generated binding class.
--You have auto generated binding class
, use that class instead of using DataBindingUtil
.
In Java
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
HomeFragmentBinding binding = HomeFragmentBinding.inflate(inflater, container, false);
//set binding variables here
return binding.getRoot();
}
In Kotlin
lateinit var binding: HomeFragmentBinding
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
binding = HomeFragmentBinding.inflate(inflater, container, false)
return binding.root
}
In DataBindingUtil class documentation you can see.
inflate
T inflate (LayoutInflater inflater, int layoutId, ViewGroup parent, boolean attachToParent)
Use this version only if layoutId is unknown in advance. Otherwise, use the generated Binding's inflate method to ensure type-safe inflation.
If your layout biniding class is not generated @See this answer.
If you are using ViewModel and LiveData This is the sufficient syntax
Kotlin Syntax:
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return MartianDataBinding.inflate(
inflater,
container,
false
).apply {
lifecycleOwner = viewLifecycleOwner
vm = viewModel // Attach your view model here
}.root
}
Just as most have said, but dont forget to set LifeCycleOwner
Sample in Java
i.e
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
BindingClass binding = DataBindingUtil.inflate(inflater, R.layout.fragment_layout, container, false);
ModelClass model = ViewModelProviders.of(getActivity()).get(ViewModelClass.class);
binding.setLifecycleOwner(getActivity());
binding.setViewmodelclass(model);
//Your codes here
return binding.getRoot();
}