数据绑定 - ObservableField<String> 不更新视图

Question

I have simple app - Button - which fetches data from rest api and a TextView where this data is displayed. I'm using MVVM architectural pattern. When ViewModel receives callback with fetched data I set it up to an ObservableField. Unfortunately it doesn't update text on the screen, but whenever I rotate device data is being updated on the screen.

OK, enough talking, I'll show you the code:

ViewModel

public class MyViewModel extends ViewModel{

private ObservableField<String> name = new ObservableField<>();

@Override
public void onListReceived(String username) {
    super.onListReceived(list);
    name.set(username);
}

public String getName() {
    return name.get();
}}

and in XML:

<TextView
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@{viewModel.name}"
        tools:text="some text"/>

As far as I read, I think it should be '=' in this line android:text="@{viewModel.name}" between ' @ ' and ' { ', but when I add it, clean project and rebuild this, I got an error that Cannot resolve DataBindingComponent .

Any ideas?
Thanks in advance!

Answer 1

Remove the getName() method, and make name be public . Or, have getName() return name , not name.get() .

The data binding system needs to be working directly with the Observable . Right now, your Observable is hidden from data binding, and so data binding has no way of registering an observer and knowing when the data changes.

As far as I read, I think it should be '=' in this line android:text="@{viewModel.name}" between '@' and '{',

That syntax ( @={viewModel.name} ) is for two-way data binding. Since the user cannot enter data into a TextView , that is not needed here.