Android实现联动下拉框，二级地市联动下拉框

日常使用软件中，为了方便且规范输入，会使用到下拉框进行输入，如注册时生日选项，购物时的地址输入，都会用到下拉框，今日笔者为了巩固已学的知识，实现了二级联动下拉框用作回顾及分享给求知的新手。

思路/步骤：

在实现联动下拉框之前，我们先对用到的ArrayAdapter和数据的封装作必要的了解，Android 中提供了很多适配器的实现类，其中ArrayAdapter就其中之一。它可以通过泛型来指定要适配的数据类型，然后在构造函数中把要适配的数据传入。如：

ArrayAdapter adapter = ArrayAdapter.createFromResource(   getApplicationContext(),     R.array.province,     android.R.layout.simple_spinner_item)；

ArrayAdapter中比较常用的泛型是String，但此处用了CharSequence(字符序列)，通过指定泛型来装配适合的数据类型。
这段代码中有三个参数：

第一个参数Context是上下文，就是当前的Activity。
第二个参数是数据来源，R.array.province是存储在xml文件中的数据。
第三个参数是Android SDK中内置的一个TextView。(此xml文件中只有一个TextView)。

通过创建一个ArrayAdapter处理存储在xml中的省份地市数据，用Spinner控件处理ArrayAdapter处理好的数据，用TextView将数据显示出来形成一个list供用户点击选择。

主要实现代码： MainActivity.java

import android.os.Bundle;import android.app.Activity;import android.view.Menu;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 {Spinner spinner1, spinner2;//声明两个下拉框String City, Province;protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);spinner1 = (Spinner) findViewById(R.id.spinner1);//绑定IDspinner2 = (Spinner) findViewById(R.id.spinner2);//绑定IDArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.province,android.R.layout.simple_spinner_item);//创建资源spinner1.setAdapter(adapter);//装配数据spinner1.setOnItemSelectedListener(new provinceClickListen());//监听事件spinner2.setOnItemSelectedListener(new CityClickListen());//监听事件}class provinceClickListen implements OnItemSelectedListener {public void onItemSelected(AdapterView<?> parent, View v, int i, long l) {Spinner spinner = (Spinner) parent;String pro = (String) spinner.getItemAtPosition(i);//获取当前选中项ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.def,R.layout.item);//初始化Province = spinner1.getSelectedItem().toString();//当前选中的省份/** 根据省份，装配地市数据**/if (pro.equals("北京")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.北京, R.layout.item);} else if (pro.equals("天津")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.天津, R.layout.item);} else if (pro.equals("河北")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.河北, R.layout.item);} else if (pro.equals("山西")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.山西, R.layout.item);} else if (pro.equals("内蒙古")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.内蒙古, R.layout.item);} else if (pro.equals("辽宁")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.辽宁, R.layout.item);} else if (pro.equals("吉林")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.吉林, R.layout.item);} else if (pro.equals("黑龙江")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.黑龙江, R.layout.item);} else if (pro.equals("上海")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.上海, R.layout.item);} else if (pro.equals("江苏")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.江苏, R.layout.item);} else if (pro.equals("浙江")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.浙江, R.layout.item);} else if (pro.equals("安徽")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.安徽, R.layout.item);} else if (pro.equals("福建")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.福建, R.layout.item);} else if (pro.equals("江西")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.江西, R.layout.item);} else if (pro.equals("山东")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.山东, R.layout.item);} else if (pro.equals("河南")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.河南, R.layout.item);} else if (pro.equals("湖北")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.湖北, R.layout.item);} else if (pro.equals("湖南")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.湖南, R.layout.item);} else if (pro.equals("广东")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.广东, R.layout.item);} else if (pro.equals("广西")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.广西, R.layout.item);} else if (pro.equals("海南")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.海南, R.layout.item);} else if (pro.equals("重庆")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.重庆, R.layout.item);} else if (pro.equals("四川")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.四川, R.layout.item);} else if (pro.equals("贵州")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.贵州, R.layout.item);} else if (pro.equals("云南")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.云南, R.layout.item);} else if (pro.equals("西藏")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.西藏, R.layout.item);} else if (pro.equals("陕西")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.陕西, R.layout.item);} else if (pro.equals("甘肃")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.甘肃, R.layout.item);} else if (pro.equals("青海")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.青海, R.layout.item);} else if (pro.equals("宁夏")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.宁夏, R.layout.item);} else if (pro.equals("新疆")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.新疆, R.layout.item);} else if (pro.equals("台湾")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.台湾, R.layout.item);} else if (pro.equals("香港")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.香港, R.layout.item);} else if (pro.equals("澳门")) {adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.澳门, R.layout.item);}spinner2.setAdapter(adapter);//装配地市数据}public void onNothingSelected(AdapterView<?> parent) {}}class CityClickListen implements OnItemSelectedListener {public void onItemSelected(AdapterView<?> parent, View v, int i, long l) {City = spinner2.getSelectedItem().toString();//当前选中的地市if (City.equals("-城市-")) {//当前还没选择地市} else {Toast.makeText(getApplicationContext(), Province+"省"+City, Toast.LENGTH_LONG).show();//Toast显示选中的省份城市}}public void onNothingSelected(AdapterView<?> parent) {}}public boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

此外还有布局文件: activity_main.xml

<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:orientation="horizontal"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <TextView        android:id="@+id/province"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="省份:" />    <Spinner        android:id="@+id/spinner1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1" />    <TextView        android:id="@+id/city"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="城市:" />    <Spinner        android:id="@+id/spinner2"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1" /></LinearLayout>

item.xml

<?xml version="1.0" encoding="utf-8"?>    <TextView  xmlns:android="http://schemas.android.com/apk/res/android"        android:id="@+id/spinner_item"        android:layout_height="wrap_content"        android:layout_width="match_parent"        android:text="名称"        android:textColor="#000"        android:textSize="16dp"/>

实现效果如下：

本文章参看作者：预言家，做学习交流所用，如有侵权，请及时反馈，感谢！

Android实现联动下拉框