OnItemSelectedListener事件与二级联动

一、界面

　　 1、新建province.xml件。

　　在“res/values”位置新建province.xml文件。

　　（1）province.xml文件位置如下图所示：

　　

　　（2）province.xml内容如下：　　

　　

　　（3）代码　　

1. <?xmlversion="1.0"encoding="utf-8"?>

2. <resources>

3. <string-arrayname="provarray">

4. <item>河南省</item>

5. <item>河北省</item>

6. <item>山东省</item>

7. <item>山西省</item>

8. </string-array>

9. </resources>

（4）main_activity布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/liuyifei"
    tools:context=".MainActivity" >

    <Spinner
        android:id="@+id/province"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:entries="@array/province"

       />

    <Spinner
        android:id="@+id/city"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"

        />

</LinearLayout>

（5）Activity(src下的Java代码)

package com.example.item2jiliandong;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends Activity {

       //声明Spinner对像
        private Spinner spinProvince=null;
        private Spinner spinCity=null;
        //定义城市数据，用于二级菜单
        private String[][] arrCity=new String[][]{
            {"郑州","开封","洛阳","安阳"},
            {"石家庄","保定","邯郸","张家口"},
            {"济南","青岛","烟台","日照"},
            {"太原","晋中","吕梁","临汾"}};
        //声明数组适配器，用来填充城市列表
        private ArrayAdapter<CharSequence> adapterCity=null;  

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //获取Spinner对象
            spinProvince=(Spinner)super.findViewById(R.id.province);
            spinCity=(Spinner)super.findViewById(R.id.city);
            //为spinProvince控件注册OnItemSelected监听器
            spinProvince.setOnItemSelectedListener(new ProvOnItemSelectedListener());
           //为spinCity控件注册OnItemSelected监听器
            spinCity.setOnItemSelectedListener(new CityOnItemSelectedListener());
            }  

        //OnItemSelected监听器
        private class  ProvOnItemSelectedListener implements OnItemSelectedListener{
            //选择省份，触发城市下拉列表框
            @Override
            public void onItemSelected(AdapterView<?> adapter,View view,int position,long id) {
               //使用ArrayAdapter转换数据
               MainActivity.this.adapterCity=new ArrayAdapter<CharSequence>(
                       MainActivity.this,
                        android.R.layout.simple_spinner_item,
                       MainActivity.this.arrCity[position]);
                //使用adapterCity数据适配器填充spinCity
               MainActivity.this.spinCity.setAdapter(MainActivity.this.adapterCity);  

            }  

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                //没有选择时执行
            }
       }
        //OnItemSelected监听器
        private class CityOnItemSelectedListener implements OnItemSelectedListener{
            //选择城市，触发显示选择的城市
            @Override
            public void onItemSelected(AdapterView<?> adapter,View view,int position,long id) {
                //获取选择的项的值
                String sInfo=adapter.getItemAtPosition(position).toString();
                Toast.makeText(getApplicationContext(), sInfo, Toast.LENGTH_LONG).show();  //MainActivity.this等价于 getApplicationContext()
            }
            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                //没有选择时执行
            }
        }    

    }

（6）运行结果

运行运用程序所得结果如下图：