Android实战简易教程-第五枪（ListView用法研究）

Android用的最多的，也最难用的应该就是ListView了，下面我们研究一下它的用法。

一、最简单的ListView

我们简单介绍一下ListView的最简单用法，不用布局文件：

package org.lxh.demo;import android.app.Activity;import android.os.Bundle;import android.widget.ArrayAdapter;import android.widget.ListView;public class MainActivity extends Activity {private String[] arrays = { "Sunday", "Monday", "Tuesday", "Wednesday","Thursday", "Friday", "Saturday" };private ListView listView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);listView = new ListView(this);listView.setAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_expandable_list_item_1, arrays));//利用ArrayAdapter对数据进行包装super.setContentView(listView);//将ListView设置为显示界面}}

运行实例如下：

二、结合ArrayAdapter实现较复杂的ListView

1.main.xml代码：

<p><?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" ></p><p> <ListView android:id="@+id/list_view" android:layout_width="fill_parent" android:layout_height="wrap_content" /></p><p></LinearLayout></p>

2.fruit_item.xml代码：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent">    <ImageView        android:id="@+id/fruit_image"        android:layout_width="wrap_content"        android:layout_height="wrap_content" />    <TextView        android:id="@+id/fruit_name"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:layout_marginLeft="10sp" /></LinearLayout>

3.Fruit.java代码如下：

package org.lxh.demo;public class Fruit {private String name;private int imageId;public Fruit(String name, int imageId) {this.name = name;this.imageId = imageId;}public String getName() {return name;}public int getImageId() {return imageId;}}

4.集成ArrayAdapter的FruitAdapter.java代码如下：

package org.lxh.demo;import java.util.List;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.ImageView;import android.widget.TextView;public class FruitAdapter extends ArrayAdapter<Fruit> {private int resourceId;public FruitAdapter(Context context, int textViewResourceId,List<Fruit> objects) {super(context, textViewResourceId, objects);resourceId = textViewResourceId;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {Fruit fruit = getItem(position);View view;ViewHolder viewHolder;if (convertView == null) {view = LayoutInflater.from(getContext()).inflate(resourceId, null);viewHolder = new ViewHolder();viewHolder.fruitImage = (ImageView) view.findViewById(R.id.fruit_image);viewHolder.fruitName = (TextView) view.findViewById(R.id.fruit_name);view.setTag(viewHolder);} else {view = convertView;viewHolder = (ViewHolder) view.getTag();}viewHolder.fruitImage.setImageResource(fruit.getImageId());viewHolder.fruitName.setText(fruit.getName());return view;}class ViewHolder {ImageView fruitImage;TextView fruitName;}}

5.MainActivity.java代码如下：

package org.lxh.demo;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.widget.ListView;public class Hello extends Activity {private List<Fruit> fruitList = new ArrayList<Fruit>();public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState); // 生命周期方法super.setContentView(R.layout.main); // 设置要使用的布局管理器initFruits();FruitAdapter adapter = new FruitAdapter(Hello.this,R.layout.fruit_item, fruitList);ListView listView = (ListView) findViewById(R.id.list_view);listView.setAdapter(adapter);}private void initFruits() {Fruit appleFruit = new Fruit("Apple", R.drawable.apple_pic);fruitList.add(appleFruit);Fruit bananaFruit = new Fruit("Banana", R.drawable.banana_pic);fruitList.add(bananaFruit);Fruit orangeFruit = new Fruit("Orange", R.drawable.orange_pic);fruitList.add(orangeFruit);Fruit waterFruit = new Fruit("Apple", R.drawable.watermelon_pic);fruitList.add(waterFruit);}}

运行实例如下：

三、结合上下文菜单实现单项的删除

修改MainActivity.java程序如下：

package org.lxh.demo;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.view.ContextMenu;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.ContextMenu.ContextMenuInfo;import android.widget.ListView;import android.widget.AdapterView.AdapterContextMenuInfo;public class Hello extends Activity {private List<Fruit> fruitList = new ArrayList<Fruit>();FruitAdapter adapter;public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState); // 生命周期方法super.setContentView(R.layout.main); // 设置要使用的布局管理器initFruits();adapter = new FruitAdapter(Hello.this, R.layout.fruit_item, fruitList);ListView listView = (ListView) findViewById(R.id.list_view);listView.setAdapter(adapter);super.registerForContextMenu(listView);//注册上下文菜单}@Overridepublic void onCreateContextMenu(ContextMenu menu, View v,// 创建菜单项ContextMenuInfo menuInfo) {super.onCreateContextMenu(menu, v, menuInfo);menu.setHeaderTitle("选择操作");menu.add(Menu.NONE, Menu.FIRST + 1, 1, "删除");menu.add(Menu.NONE, Menu.FIRST + 2, 2, "取消");}@Overridepublic boolean onContextItemSelected(MenuItem item) {// 选择监听AdapterContextMenuInfo acmiRef = (AdapterContextMenuInfo) item.getMenuInfo();// 用来获取item信息哎，重要int removeIndex = acmiRef.position;switch (item.getItemId()) {case Menu.FIRST + 1:fruitList.remove(removeIndex);adapter.notifyDataSetChanged();// 删除后刷新ListViewbreak;case Menu.FIRST + 2:break;default:break;}return false;}private void initFruits() {Fruit appleFruit = new Fruit("Apple", R.drawable.apple_pic);fruitList.add(appleFruit);Fruit bananaFruit = new Fruit("Banana", R.drawable.banana_pic);fruitList.add(bananaFruit);Fruit orangeFruit = new Fruit("Orange", R.drawable.orange_pic);fruitList.add(orangeFruit);Fruit waterFruit = new Fruit("Apple", R.drawable.watermelon_pic);fruitList.add(waterFruit);}}

运行实例：

选择删除后：

总结

1.super.registerForContextMenu(listView);//注册上下文菜单

2.adapter.notifyDataSetChanged();// 删除后刷新ListView

3.AdapterContextMenuInfo acmiRef = (AdapterContextMenuInfo) item.getMenuInfo();// 用来获取当前item信息，重要

int removeIndex = acmiRef.position;//获取点击位置的坐标

一、最简单的ListView

二、结合ArrayAdapter实现较复杂的ListView

三、结合上下文菜单实现单项的删除

总结

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