无涯教程-Android - Spinner函数

Spinner允许您从下拉菜单中选择一个项目

例如。使用Gmail应用程序时,将显示如下所示的下拉菜单,您需要从下拉菜单中选择一个项目。

Spinner Example

示例

本示例演示计算机的类别,您需要从类别中选择一个类别。

以下是修改后的主要Activity文件src/com.example.spinner/AndroidSpinnerExampleActivity.java的内容。

package com.example.spinner;

import java.util.ArrayList;
import java.util.List; 
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;
 
class AndroidSpinnerExampleActivity extends Activity implements OnItemSelectedListener{
   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      
      //Spinner element
      Spinner spinner = (Spinner) findViewById(R.id.spinner);
      
      //Spinner click listener
      spinner.setOnItemSelectedListener(this);
      
      //Spinner Drop down elements
      List<String> categories = new ArrayList<String>();
      categories.add("Automobile");
      categories.add("Business Services");
      categories.add("Computers");
      categories.add("Education");
      categories.add("Personal");
      categories.add("Travel");
      
      //Creating adapter for spinner
      ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, categories);
      
      //Drop down layout style - list view with radio button
      dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
      
      //attaching data adapter to spinner
      spinner.setAdapter(dataAdapter);
   }
   
   @Override
   public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
      //On selecting a spinner item
      String item = parent.getItemAtPosition(position).toString();
      
      //Showing selected spinner item
      Toast.makeText(parent.getContext(), "Selected: " + item, Toast.LENGTH_LONG).show();
   }
   public void onNothingSelected(AdapterView<?> arg0) {
      //TODO Auto-generated method stub
   }
}

将 res/layout/activity_main.xml 的内容修改为以下内容

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:padding="10dip"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content">
   
   <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="10dip"
      android:text="Category:"
      android:layout_marginBottom="5dp"/>
      
   <Spinner
      android:id="@+id/spinner"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:prompt="@string/spinner_title"/>
      
</LinearLayout>

将 res/values/string.xml 修改为以下内容

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <string name="app_name">AndroidSpinnerExample</string>
</resources>

这是默认的 AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.spinner" >

   <application
      android:allowBackup="true"
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/AppTheme" >
      
      <activity
         android:name="com.example.spinner.AndroidSpinnerExampleActivity"
         android:label="@string/app_name" >
      
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      
      </activity>
      
   </application>
</manifest>