（四）适配器Adapter

只对简单应用进行描述。适配器与ListView配合使用可以快速生成item，效果如下例所示

一、简单模式

方式一

xml

    <ListView
        android:id="@+id/lv_test"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"


     />

java

package com.example.app03;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.LinkedList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List<Animal> mData = null;
    private Context mContext;
    private AnimalAdapter mAdapter = null;
    private ListView list_animal;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //要显示的数据
        String[] strs = {"AA","BB","CC","DD","EE","FF","GG","HH","II","JJ"};
        //创建ArrayAdapter
        ArrayAdapter<String> adapter = new ArrayAdapter<String>
                (this,android.R.layout.simple_list_item_single_choice ,strs);
        //获取ListView对象，通过调用setAdapter方法为ListView设置Adapter设置适配器
        ListView list_test = (ListView) findViewById(R.id.lv_test);
        list_test.setAdapter(adapter);

    }
}

效果

方式二

创建ListText（即显示的item信息）：选中Values-右键new-xml-values xml file，如下图所示。

在文件中添加如下内容，其中name即为此数据文件的标识，定义好此文件后方式一中的adapter也可以这样定义（此方法不需要下述代码）

        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
               R.array.ListText,android.R.layout.simple_list_item_multiple_choice );

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="ListText">
        <item>item1</item>
        <item>item2</item>
        <item>item3</item>
    </string-array>
</resources>

 xml

 android:entries="@array/ListText" 比方法一增加的一行，默认数据在ListText中

    <ListView
        android:id="@+id/lv_test"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:entries="@array/ListText"             
     />

 直接运行即可如下效果

一、复杂模式

 先来一个效果图

1）准备三张图片

2）新建一个布局，xml文件如下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- 定义一个用于显示头像的ImageView -->
    <ImageView
        android:id="@+id/iv_head"
        android:baselineAlignBottom="true"
        android:paddingLeft="8dp"
        android:layout_width="64dp"
        android:layout_height="64dp" />

    <!-- 定义一个竖直方向的LinearLayout,把QQ呢称与说说的文本框设置出来 -->
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/tv_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="8dp"
            android:textColor="#1D1D1C"
            android:textSize="20sp" />
        <TextView
            android:id="@+id/tv_says"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="8dp"
            android:textColor="#1D1D1C"
            android:textSize="20sp" />

    </LinearLayout>

</LinearLayout>

3）新建两个类：Animal动物类用来存储动物的图标，name和说说；AnimalAdapter类继承BaseAdapter

package com.example.app03;

public class Animal
{
    private String aName;
    private String aSpeak;
    private int aIcon;

    public Animal() {
    }

    public Animal(String aName, String aSpeak, int aIcon) {
        this.aName = aName;
        this.aSpeak = aSpeak;
        this.aIcon = aIcon;
    }

    public String getaName() {
        return aName;
    }

    public String getaSpeak() {
        return aSpeak;
    }

    public int getaIcon() {
        return aIcon;
    }

    public void setaName(String aName) {
        this.aName = aName;
    }

    public void setaSpeak(String aSpeak) {
        this.aSpeak = aSpeak;
    }

    public void setaIcon(int aIcon) {
        this.aIcon = aIcon;
    }
}

package com.example.app03;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.LinkedList;

public class AnimalAdapter extends BaseAdapter
{
    private LinkedList<Animal> mData;
    private Context mContext;

    public AnimalAdapter(LinkedList<Animal> mData, Context mContext) {
        this.mData = mData;
        this.mContext = mContext;
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        convertView = LayoutInflater.from(mContext).inflate(R.layout.animal_list,parent,false);
        ImageView img_icon = (ImageView) convertView.findViewById(R.id.iv_head);
        TextView txt_aName = (TextView) convertView.findViewById(R.id.tv_name);
        TextView txt_aSpeak = (TextView) convertView.findViewById(R.id.tv_says);
        img_icon.setBackgroundResource(mData.get(position).getaIcon());
        txt_aName.setText(mData.get(position).getaName());
        txt_aSpeak.setText(mData.get(position).getaSpeak());
        return convertView;
    }
}

4）MainActivity中代码

package com.example.app03;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.LinkedList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List<Animal> mData = null;
    private Context mContext;
    private AnimalAdapter mAdapter = null;
    private ListView list_animal;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
     

        mContext = MainActivity.this;
        list_animal = (ListView) findViewById(R.id.lv_test);
        mData = new LinkedList<Animal>();
        mData.add(new Animal("狗1", "我是狗1",  R.drawable.aa));
        mData.add(new Animal("狗2", "我是狗2",  R.drawable.bb));
        mData.add(new Animal("狗3", "我是狗3",  R.drawable.cc));
        mAdapter = new AnimalAdapter((LinkedList<Animal>) mData, mContext);
        list_animal.setAdapter(mAdapter);
    }
}

原文链接：http://www.runoob.com/w3cnote/android-tutorial-adapter.html