周末翻了翻书，发现才歇了一两个月没看Android，好多看的东西又都还给书了，遂决定将所学的写到博客中，权当笔记（代码为主），巩固所学知识。
整理的下拉列表框示例代码中，主要分为以下部分：静态绑定下拉框数据、动态绑定下拉框数据、选择时触发的事件以及获得所选的值；
1、静态绑定下拉框数据
需要将数据写在xml中，然后设置下拉框的entries属性，则数据自动加载到下拉框中。具体如下：
在value文件夹中新建cityInfo.xml，xml中写入
<?xml version="1.0" encoding="utf-8"?><resources><string-array name="cityArray"><item>北京</item><item>江苏</item> <item>浙江</item><item>上海</item> </string-array></resources>
设计页面控件代码：
<Spinner android:id="@+id/spinnerCityStatic"android:layout_width="wrap_content"android:layout_height="wrap_content"android:entries="@array/cityArray"/>
2、动态绑定下拉框数据
主要三个步骤，1.获得数据列表；2.填充数据适配器；3.设置下拉框的适配器；
private Spinner spCity = null;private ArrayAdapter<CharSequence> adapterCity = null;private static String[] cityInfo={"北京","江苏","浙江","上海"};//初始化函数中代码如下this.spCity = (Spinner) super.findViewById(R.id.spinnerCity);//将数据cityInfo填充到适配器adapterCity中this.adapterCity = new ArrayAdapter<CharSequence>(this,android.R.layout.simple_spinner_dropdown_item, cityInfo);//设置下拉框的数据适配器adapterCitythis.spCity.setAdapter(adapterCity);
3、选择时触发的事件
需要实现OnItemSelectedListener接口的onItemSelected方法，代码如下
//下拉框选择事件private class OnItemSelectedListenerImpl implements OnItemSelectedListener {@Overridepublic void onItemSelected(AdapterView<?> parent, View view,int position, long id) {String city = parent.getItemAtPosition(position).toString();Toast.makeText(MainActivity.this, "选择的城市是：" + city,Toast.LENGTH_LONG).show();}@Overridepublic void onNothingSelected(AdapterView<?> parent) {// TODO Auto-generated method stub}}
4、获得下拉框所选的值
String cityStatic = spCityStatic.getSelectedItem().toString();
项目完整代码：
前台设计页面activity_main.xml如下：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="/apk/res/android"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><Spinner android:id="@+id/spinnerCityStatic"android:layout_width="wrap_content"android:layout_height="wrap_content"android:entries="@array/cityArray"/><Spinner android:id="@+id/spinnerCity"android:layout_width="wrap_content"android:layout_height="wrap_content"/><Button android:id="@+id/btnShowCity"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="查看选择的结果"/></LinearLayout>
后台页面MainActivity.java代码：
package com.example.spinner0803;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.AdapterView;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.ArrayAdapter;import android.widget.Button;import android.widget.Spinner;import android.widget.Toast;public class MainActivity extends Activity {private Button btnShowCity = null;private Spinner spCityStatic = null;private Spinner spCity = null;private ArrayAdapter<CharSequence> adapterCity = null;private static String[] cityInfo={"北京","江苏","浙江","上海"};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//按钮相关btnShowCity = (Button) super.findViewById(R.id.btnShowCity);btnShowCity.setOnClickListener(new OnClickListenerImpl());//静态实现的下拉框，数据写在cityInfo.xml文件中this.spCityStatic = (Spinner) super.findViewById(R.id.spinnerCityStatic);this.spCityStatic.setOnItemSelectedListener(new OnItemSelectedListenerImpl());//动态实现的下拉框，数据在程序中获得，实际项目可能来自数据库等this.spCity = (Spinner) super.findViewById(R.id.spinnerCity);this.adapterCity = new ArrayAdapter<CharSequence>(this,android.R.layout.simple_spinner_dropdown_item, cityInfo);this.spCity.setAdapter(adapterCity);this.spCity.setOnItemSelectedListener(new OnItemSelectedListenerImpl());}//按钮点击事件private class OnClickListenerImpl implements OnClickListener {@Overridepublic void onClick(View v) {String cityStatic = spCityStatic.getSelectedItem().toString();String city = spCity.getSelectedItem().toString();String selectInfo = "第一个选择的城市是：" + city + "，第二个选择的城市是："+ cityStatic;Toast.makeText(MainActivity.this, selectInfo, Toast.LENGTH_LONG).show();}}//下拉框选择事件private class OnItemSelectedListenerImpl implements OnItemSelectedListener {@Overridepublic void onItemSelected(AdapterView<?> parent, View view,int position, long id) {String city = parent.getItemAtPosition(position).toString();Toast.makeText(MainActivity.this, "选择的城市是：" + city,Toast.LENGTH_LONG).show();}@Overridepublic void onNothingSelected(AdapterView<?> parent) {// TODO Auto-generated method stub}}}
项目运行截图：
项目源码下载
