Android实现联动下拉框二级地市联动下拉框功能

Z时代
2024-01-10
分类：IT

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<CharSequence> 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ID
 spinner2 = (Spinner) findViewById(R.id.spinner2);//绑定ID
 ArrayAdapter<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：

在这里插入图片描述