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;
@Override
protected 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;
}
@Override
public 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
}
@Override
public 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");
}
@Override
public 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ListView
break;
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