How to databind livedata object (android)

问题

Today I've some question about mvvm and databinding on android,

I'm trying to bind object properties on view.

I've an Object (Model) with some properties, by example :

public String name;
public String title;
public int value;

I've a ViewModel with livedata like this :

MutableLiveData<Object> _obj = new MutableLiveData<>();
public LiveData<Object> obj = _obj;

And, at last, I've a view like this :

<layout>
    <data>
        <variable
            name="viewModel">
            type="com.sample.app.viewmodels.MainViewModel" />
    </data>
    <LinearLayout
        ... >
        <TextView
            android:text:="@{viewModel.obj.name}"
            .../>
    </LinearLayout>
</layout>

I saw that we can do that in a video from "Android Developers" about "LiveData" : https://youtu.be/OMcDk2_4LSk?t=102

She says that its possible in Android studio on 3.1+ versions. But this is not working for me.

回答1:

For this to work, your model class must extend BaseObservable class from databinding library. And you have to call notifyChange() on each setter method like this:

public class Object extends BaseObservable {
    public String name;
    public String title;
    public int value;

    public void setName(String name) {
        this.name = name;
        notifyChange();
    }

    public void setTitle(String title) {
        this.title = title;
        notifyChange();
    }

    public void setValue(int value) {
        this.value = value;
        notifyChange();
    }
}

来源：https://stackoverflow.com/questions/56908707/how-to-databind-livedata-object-android