public class

ListView

extends AbsListView

java.lang.Object
↳	android.view.View
	↳	android.view.ViewGroup
		↳	android.widget.AdapterView<T extends android.widget.Adapter>
			↳	android.widget.AbsListView
				↳	android.widget.ListView

public class

ArrayAdapter

extends BaseAdapter
implements Filterable

java.lang.Object
↳	android.widget.BaseAdapter
	↳	android.widget.ArrayAdapter<T>

Class Overview

A concrete BaseAdapter that is backed by an array of arbitrary objects. By default this class expects that the provided resource id references a single TextView. If you want to use a more complex layout, use the constructors that also takes a field id. That field id should reference a TextView in the larger layout resource.

However the TextView is referenced, it will be filled with the toString() of each object in the array. You can add lists or arrays of custom objects. Override the toString() method of your objects to determine what text will be displayed for the item in the list.

To use something other than TextViews for the array display, for instance, ImageViews, or to have some of data besides toString() results fill the views, overridegetView(int, View, ViewGroup) to return the type of view you want.

<RelativeLayout 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: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="sunny.example.listviewsimple.MainActivity" ><ListViewandroid:id="@+id/list_view"android:layout_width="match_parent"android:layout_height="match_parent"/></RelativeLayout>

package sunny.example.listviewsimple;import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;public class MainActivity extends ActionBarActivity {private String[] data = {"Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","Cherry","Mango"};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, data);ListView listView = (ListView)findViewById(R.id.list_view);listView.setAdapter(adapter);}
}

package com.example.listviewtest;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;}}

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

子item布局中定义一个ImageView用于显示水果图片，TextView用于显示水果名字。

创建一个自定义适配器FruitAdapter继承自ArrayAdapter,将泛型指定为Fruit类。

 

FruitAdapter中用到的类与方法：

public static LayoutInflater from (Context context)

public View inflate (int resource,ViewGroup root)

 

FruitAdapter.java

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){//得到当前项的Fruit实例Fruit fruit = getItem(position);//LayoutInflater来为这个子项加载布局View view = LayoutInflater.from(getContext()).inflate(resourceId,null);ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);TextView textView = (TextView) view.findViewById(R.id.fruit_name);fruitImage.setImageResource(fruit.getImageId());fruitName.setText(fruit.getName());return view;}
}

重写了ArrayAdapter的 getView()方法，这个方法在每个子item被滚动到屏幕内的时候会被调用。

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){//得到当前项的Fruit实例Fruit fruit = getItem(position);View view;//convertView为空，使用LayoutInflater加载布局//不为空，则直接对convertView进行重用if(convertView==null){view = LayoutInflater.from(getContext()).inflate(resourceId, null);}else{view = convertView;}ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);TextView textView = (TextView) view.findViewById(R.id.fruit_name);fruitImage.setImageResource(fruit.getImageId());fruitName.setText(fruit.getName());return view;}
}

优化方法二：新增一个内部类ViewHolder：

 

class ViewHolder{ImageView fruitImage;TextView fruitName;}

用于对对象的实例进行缓存。当convertView为空，创建一个ViewHolder对象，并将控件的实例都存放在ViewHolder里，然后调用View的setTag()方法将ViewHolder 对象存储在view中。当convertView不为空时，调用View的getTag()方法把ViewHolder取出。这样所有的控件实例都缓存在ViewHolder里了，就不用每次都通过findViewById()方法获取控件实例了。

 

FruitAdapter.java

package com.example.listviewtest;import java.util.List;import android.annotation.SuppressLint;
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;@SuppressLint("ViewHolder")
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();}//View view = LayoutInflater.from(getContext()).inflate(resourceId,null);//ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);//TextView fruitName = (TextView) view.findViewById(R.id.fruit_name);//fruitImage.setImageResource(fruit.getImageId());//fruitName.setText(fruit.getName());viewHolder.fruitImage.setImageResource(fruit.getImageId());viewHolder.fruitName.setText(fruit.getName());return view;}class ViewHolder{ImageView fruitImage;TextView fruitName;}}

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"><ListViewandroid:id="@+id/list_view"android:layout_width="match_parent"android:layout_height="match_parent"></ListView></LinearLayout>

 

MainActivity.java

package com.example.listviewtest;import java.util.ArrayList;
import java.util.List;import android.app.Activity;
import android.content.Context;
//import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Toast;import android.widget.ListView;public class MainActivity extends Activity {private String[] data = {"Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","cherry","Mango"};private List<Fruit> fruitList = new ArrayList<Fruit>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initFruits();
//public FruitAdapter(Context context,int textViewResourceId,List<Fruit> objects) FruitAdapter adapter = new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList);//ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,data);ListView listView = (ListView) findViewById(R.id.list_view);listView.setAdapter(adapter);listView.setOnItemClickListener(new OnItemClickListener(){@Overridepublic void onItemClick(AdapterView<?> parent, View view,int position, long id) {// TODO Auto-generated method stubFruit fruit = fruitList.get(position);Toast.makeText(MainActivity.this, fruit.getName(), Toast.LENGTH_SHORT).show();}});}private void initFruits() {// TODO Auto-generated method stubFruit apple = new Fruit("Apple",R.drawable.ic_launcher);fruitList.add(apple);Fruit banana = new Fruit("Banana",R.drawable.ic_launcher1);fruitList.add(banana);Fruit orange = new Fruit("Orange",R.drawable.ic_launcher2);fruitList.add(orange);Fruit Watermelon = new Fruit("Watermelon",R.drawable.ic_launcher3);fruitList.add(Watermelon);Fruit Pear = new Fruit("Pear",R.drawable.ic_launcher4);fruitList.add(Pear);Fruit Grape = new Fruit("Grape",R.drawable.ic_launcher5);fruitList.add(Grape);Fruit Pineapple = new Fruit("Pineapple",R.drawable.ic_launcher6);fruitList.add(Pineapple);Fruit Strawberry = new Fruit("S trawberry",R.drawable.ic_launcher7);fruitList.add(Strawberry);Fruit cherry = new Fruit("Cherry",R.drawable.ic_launcher8);fruitList.add(cherry);Fruit mango = new Fruit("Mango",R.drawable.ic_launcher9);fruitList.add(mango);}
}