Android双向绑定Integer类型问题

<EditText
    android:id="@+id/editText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:text="@={viewModel.integerValue}" />

public class ViewModel extends BaseObservable {
    private Integer integerValue;

    @Bindable
    public Integer getIntegerValue() {
        return integerValue;
    }

    public void setIntegerValue(Integer integerValue) {
        this.integerValue = integerValue;
        notifyPropertyChanged(BR.integerValue);
    }
}

public class MainActivity extends AppCompatActivity {
    private ViewModel viewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        viewModel = new ViewModel();
        binding.setViewModel(viewModel);
        binding.setLifecycleOwner(this);
    }
}