ViewModel Databinding

activity_barometer.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>
        <variable
            name="viewModel"
            type="com.willowtreeapps.android.elevatorroom.BarometerViewModel" />
    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@{viewModel.getPressure}" />
    </FrameLayout>
</layout>

BarometerActivity.java

public class BarometerActivity extends LifecycleActivity {
    private BarometerViewModel viewModel;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityBarometerBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_barometer);
        viewModel = ViewModelProviders.of(this).get(BarometerViewModel.class);
        viewModel.startObserving(this);
        binding.setViewModel(viewModel);
    }
}

BarometerViewModel.java

public class BarometerViewModel extends AndroidViewModel implements Observable {
    private BarometerLiveData data;

    public BarometerViewModel(Application app) {
        super(app);
        data = new BarometerLiveData(getApplication()); // You can either get a context through your app, or better yet inject it with Dagger.
    }

    public void startObserving(LifecycleOwner lifecycleOwner) {
        data.observe(lifecycleOwner, sensorData -> notifyPropertyChanged(BR.pressure));
    }

    @Bindable
    public String getPressure() {
        return "SensorData: " + data.getValue();
    }
  
  //This is all just copied from BaseObservable so we can use this ViewModel as our backing Databinding model 

    private transient PropertyChangeRegistry mCallbacks;

    @Override
    public void addOnPropertyChangedCallback(OnPropertyChangedCallback callback) {
        synchronized (this) {
            if (mCallbacks == null) {
                mCallbacks = new PropertyChangeRegistry();
            }
        }
        mCallbacks.add(callback);
    }

    @Override
    public void removeOnPropertyChangedCallback(OnPropertyChangedCallback callback) {
        synchronized (this) {
            if (mCallbacks == null) {
                return;
            }
        }
        mCallbacks.remove(callback);
    }

    public void notifyChange() {
        synchronized (this) {
            if (mCallbacks == null) {
                return;
            }
        }
        mCallbacks.notifyCallbacks(this, 0, null);
    }

    public void notifyPropertyChanged(int fieldId) {
        synchronized (this) {
            if (mCallbacks == null) {
                return;
            }
        }
        mCallbacks.notifyCallbacks(this, fieldId, null);
    }
}