Android DataBinding 当中，如何传入方法参数

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

    <data>

        <variable
            name="cityModel"
            type="com.li_xyz.mvvm.viewmodel.CityModel" />

    </data>

    <RelativeLayout

        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="20dp">

        <EditText
            android:id="@+id/cityName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <Button
            android:id="@+id/search"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/cityName"
            android:onClick="这里该怎么写？"
            android:text="查询" />

    </RelativeLayout>
</layout>

CityModel 当中有一个 search(String cityName) 方法

想要实现的结果是，点击按钮，调用 search 方法，同时将 EditText 输入的内容作为参数传入

Button 的 android:onClick 该怎么写呢？

DataBinding 刚学了一点儿皮毛，不是很了解，请大神赐教

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

    <data>

        <variable  name="viewModel" type="com.mmlovesyy.bindingadapterdemo.NamesViewModel" />
    </data>

    <LinearLayout  android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin">

        <Button  android:id="@+id/add_btn" android:layout_width="match_parent" android:layout_height="wrap_content" android:onClick="@{viewModel.onClick}" android:text="+" />

        <LinearLayout  android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" app:context="@{viewModel.context}" app:names="@{viewModel.names}"></LinearLayout>


    </LinearLayout>


</layout>

 public class MainActivity extends AppCompatActivity {

    private NamesViewModel viewModel = new NamesViewModel(this);

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

@{() -> cityModel.search(cityName)}