Android實現聯動下拉框二級地市聯動下拉框功能

2019-10-21 21:34:33

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日常使用軟件中，為了方便且規范輸入，會使用到下拉框進行輸入，如注冊時生日選項，購物時的地址輸入，都會用到下拉框，今日筆者為了鞏固已學的知識，實現了二級聯動下拉框用作回顧及分享給求知的新手。

思路/步驟：

在實現聯動下拉框之前，我們先對用到的ArrayAdapter和數據的封裝作必要的了解，Android 中提供了很多適配器的實現類，其中ArrayAdapter就其中之一。它可以通過泛型來指定要適配的數據類型，然后在構造函數中把要適配的數據傳入。如：

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

ArrayAdapter中比較常用的泛型是String，但此處用了CharSequence(字符序列)，通過指定泛型來裝配適合的數據類型。

這段代碼中有三個參數：

第一個參數Context是上下文，就是當前的Activity。
第二個參數是數據來源，R.array.province是存儲在xml文件中的數據。
第三個參數是Android SDK中內置的一個TextView。(此xml文件中只有一個TextView)。

通過創建一個ArrayAdapter處理存儲在xml中的省份地市數據，用Spinner控件處理ArrayAdapter處理好的數據，用TextView將數據顯示出來形成一個list供用戶點擊選擇。

主要實現代碼： 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;//聲明兩個下拉框 String City, Province; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); spinner1 = (Spinner) findViewById(R.id.spinner1);//綁定ID spinner2 = (Spinner) findViewById(R.id.spinner2);//綁定ID ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.province,  android.R.layout.simple_spinner_item);//創建資源 spinner1.setAdapter(adapter);//裝配數據 spinner1.setOnItemSelectedListener(new provinceClickListen());//監聽事件 spinner2.setOnItemSelectedListener(new CityClickListen());//監聽事件 }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);//獲取當前選中項  ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.def,   R.layout.item);//初始化  Province = spinner1.getSelectedItem().toString();//當前選中的省份  /** 根據省份，裝配地市數據**/  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("內蒙古")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.內蒙古, R.layout.item);  } else if (pro.equals("遼寧")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.遼寧, R.layout.item);  } else if (pro.equals("吉林")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.吉林, R.layout.item);  } else if (pro.equals("黑龍江")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.黑龍江, R.layout.item);  } else if (pro.equals("上海")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.上海, R.layout.item);  } else if (pro.equals("江蘇")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.江蘇, 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("山東")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.山東, 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("廣東")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.廣東, R.layout.item);  } else if (pro.equals("廣西")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.廣西, R.layout.item);  } else if (pro.equals("海南")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.海南, R.layout.item);  } else if (pro.equals("重慶")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.重慶, R.layout.item);  } else if (pro.equals("四川")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.四川, R.layout.item);  } else if (pro.equals("貴州")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.貴州, 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("陜西")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.陜西, R.layout.item);  } else if (pro.equals("甘肅")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.甘肅, R.layout.item);  } else if (pro.equals("青海")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.青海, R.layout.item);  } else if (pro.equals("寧夏")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.寧夏, R.layout.item);  } else if (pro.equals("新疆")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.新疆, R.layout.item);  } else if (pro.equals("臺灣")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.臺灣, R.layout.item);  } else if (pro.equals("香港")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.香港, R.layout.item);  } else if (pro.equals("澳門")) {  adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.澳門, R.layout.item);  }  spinner2.setAdapter(adapter);//裝配地市數據 } public void onNothingSelected(AdapterView<?> parent) { } } class CityClickListen implements OnItemSelectedListener { public void onItemSelected(AdapterView<?> parent, View v, int i, long l) {  City = spinner2.getSelectedItem().toString();//當前選中的地市  if (City.equals("-城市-")) {//當前還沒選擇地市  } else {  Toast.makeText(getApplicationContext(), Province+"省"+City, Toast.LENGTH_LONG).show();//Toast顯示選中的省份城市  } } 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; }}

此外還有布局文件: 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="名稱"    android:textColor="#000"    android:textSize="16dp"/>

實現效果如下：

Android,聯動下拉框