Spinner-下拉列表的使用

package com.qf.day04spinnerdemo3;

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.AdapterView.OnItemSelectedListener;

import android.widget.ArrayAdapter;

import android.widget.Spinner;

import android.widget.Toast;

public class MainActivity extends Activity {

Spinner foodSpinner;

ArrayAdapter<String> adapter;

//数据源准备：从网络服务器上下载菜单，解析，得到数据

List<String> foodList = new ArrayList<>();

String[] addFoods = {"清蒸排骨","水煮肉片","酸菜鱼"};

int index = 0;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

foodList.add("红烧土豆");

foodList.add("红烧鲫鱼");

foodList.add("红烧排骨");

foodList.add("红烧茄子");

foodList.add("红烧肉");

foodSpinner = (Spinner) findViewById(R.id.food_spinner);

adapter = new ArrayAdapter<>(MainActivity.this, android.R.layout.simple_list_item_1, foodList);

adapter.setDropDownViewResource(android.R.layout.simple_list_item_single_choice);

foodSpinner.setAdapter(adapter);

foodSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {

@Override

public void onItemSelected(AdapterView<?> parent, View view,

int position, long id) {

// TODO Auto-generated method stub

Toast.makeText(MainActivity.this, "选中了"+foodList.get(position), Toast.LENGTH_SHORT).show();

}

@Override

public void onNothingSelected(AdapterView<?> parent) {

// TODO Auto-generated method stub

Toast.makeText(MainActivity.this, "终于调用了onNothingSelected", Toast.LENGTH_SHORT).show();

}

});

}

public void clickDelete(View view) {

foodList.remove(0);

adapter.notifyDataSetChanged();

}

public void clickAdd(View view) {

if (index < addFoods.length) {

foodList.add(addFoods[index]);

adapter.notifyDataSetChanged();

index++;

}else {

Toast.makeText(MainActivity.this, "没有菜了！", Toast.LENGTH_SHORT).show();

}

}

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/LinearLayout1"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

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="com.qf.day04spinnerdemo3.MainActivity" >

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="请点餐" />

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:onClick="clickAdd"

android:text="加入新菜"/>

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:onClick="clickDelete"

android:text="删除一个菜"/>

<Spinner

android:id="@+id/food_spinner"

android:layout_width="match_parent"

android:layout_height="wrap_content" />

</LinearLayout>