How to use data-binding with Fragment

Question

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?

Answer 1

A complete example in databinding Fragments

public class MyPrograms extends Fragment {
    FragmentMyProgramsBinding fragmentMyProgramsBinding;

    public MyPrograms() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
    FragmentMyProgramsBinding    fragmentMyProgramsBinding = DataBindingUtil.inflate(inflater, R
                .layout.fragment_my_programs, container, false);
        return fragmentMyProgramsBinding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

    }
}

Answer 2

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.

Answer 3

Kotlin syntax:

lateinit var binding: MartianDataBinding
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    binding = DataBindingUtil.inflate(inflater, R.layout.martian_data, container, false)
    return binding.root
}

Answer 4

Another example in Kotlin:

override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    val binding = DataBindingUtil
            .inflate< MartianDataBinding >(
                    inflater,
                    R.layout.bla,
                    container,
                    false
            )

    binding.modelName = // ..

    return binding.root
}

Note that the name "MartianDataBinding" depends on the name of the layout file. If the file is named "martian_data" then the correct name would be MartianDataBinding.

Answer 5

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 {
        setLifecycleOwner(this@MartianData)
        vm = viewModel    // Attach your view model here
    }.root
}

Answer 6

Try this in Android DataBinding

FragmentMainBinding binding;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        binding = DataBindingUtil.inflate(inflater, R.layout.fragment_main, container, false);
        View rootView = binding.getRoot();
        initInstances(savedInstanceState);
        return rootView;
}