自定义setDropDownViewResource微调项目的示例

Question

我想在我的微调器的下拉视图中显示两个值.

目前,它只有一个城市名称,但我还想为它添加一个小距离字段.

    MyCity<MyCityDistance> dataAdapter;  

    dataAdapter = new MyCity(this, R.layout.mycityrow, list);
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

我拥有自定义数据适配器的所有代码,扩展了我的视图和持有者等.

但是,显示的项目不显示城市及其与当前位置的距离.

它只显示MyCityDistance类的toString()方法中被覆盖的内容.

我甚至尝试过设置

dataAdapter.setDropDownViewResource(R.layout.mycityrow);

但是,没有成功.它抛出一个错误.

04-02 11:05:22.600: E/AndroidRuntime(367): java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView
04-02 11:05:22.600: E/AndroidRuntime(367):  at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:347)
04-02 11:05:22.600: E/AndroidRuntime(367):  at android.widget.ArrayAdapter.getDropDownView(ArrayAdapter.java:376)
04-02 11:05:22.600: E/AndroidRuntime(367):  at android.widget.Spinner$DropDownAdapter.getDropDownView(Spinner.java:332)

创建自定义的好例子是setDropDownViewResource()什么？

即使我注释掉这一setDropDownViewResource()行,我也会得到同样的错误.

注意:唯一的效果mycityrow当前是Spinner的第一个元素按照布局显示mycityrow.但是,当我单击打开下拉列表时,该布局将丢失.在下拉选择期间我也想要相同的布局.

Answer 1

请注意,下面的示例使用内置的android.R.layout.simple_list_item_2,不幸的是文本颜色可能与背景相同.您可以通过创建自己的自定义视图来解决此问题,并在适配器中使用它.

让我知道我是否应该解释它的任何部分.

public class MainActivity extends Activity {

    class City {
        public City(String city, int d) {
            this.city = city;
            this.distance = String.valueOf(d);
        }

        String city;
        String distance;
    }

    class CityAdapter extends ArrayAdapter<City> {

        public CityAdapter(Context context, List<City> objects) {
            super(context, android.R.layout.simple_list_item_2, objects);
        }

        @Override //don't override if you don't want the default spinner to be a two line view
        public View getView(int position, View convertView, ViewGroup parent) {
            return initView(position, convertView);
        }

        @Override
        public View getDropDownView(int position, View convertView,
                                    ViewGroup parent) {
            return initView(position, convertView);
        }

        private View initView(int position, View convertView) {
            if(convertView == null)
                convertView = View.inflate(getContext(),
                                           android.R.layout.simple_list_item_2,
                                           null);
            TextView tvText1 = (TextView)convertView.findViewById(android.R.id.text1);
            TextView tvText2 = (TextView)convertView.findViewById(android.R.id.text2);
            tvText1.setText(getItem(position).city);
            tvText2.setText(getItem(position).distance);
            return convertView;
        }
    }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Spinner spinner = (Spinner)findViewById(R.id.spinner1);
        List<City> list = new ArrayList<MainActivity.City>();
        for(int i = 0; i < 10; i++)
            list.add(new City(String.format("City %d", i + 1), (i + 1) * 1000));
        spinner.setAdapter(new CityAdapter(this, list));

    }

}