下拉列表监听

?Spinner组件的主要功能是用于进行下拉列表显示的功能，当用户选中下拉列表中的某个选项之后可以使用Spinner类中提供的setOnItemClickListener()方法进行监听。

private Spinner city = null;        // 定义下拉列表框
    private Spinner area = null;        // 定义下拉列表框
    private String[][] areaData = new String[][] {        // 定义联动菜单项
            { "东城", "西城", "朝阳", "大兴", "平谷" }, // 第一级子选项
            { "黄浦", "杨浦", "闵行" },     // 第二级子选项
            { "广州" } };        // 第三级子选项
    private ArrayAdapter<CharSequence> adapterArea = null;     // 下拉列表内容适配器
    @Override
    public void onCreate(Bundle savedInstanceState) {
        this.city.setOnItemSelectedListener(
            new OnItemSelectedListenerImpl());    // 设置监听器
    }
    private class OnItemSelectedListenerImpl implements OnItemSelectedListener {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view,
                int position, long id) {        // 选项选中时触发
            MySpinnerListenerDemo.this.adapterArea = new ArrayAdapter<CharSequence>(
                    MySpinnerListenerDemo.this,
                    android.R.layout.simple_spinner_item,
                    MySpinnerListenerDemo.this.areaData[position]);
            MySpinnerListenerDemo.this.adapterArea.setDropDownViewResource(
                    android.R.layout.simple_spinner_dropdown_item);
            MySpinnerListenerDemo.this.area
                    .setAdapter(MySpinnerListenerDemo.this.adapterArea);
        }
        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {    // 没有选项时触发
        }
    }

020604_下拉列表框与OnItemSelectedListener.ppt