AS中ListView BaseAdapter使用

1. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/RelativeLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/list_animal"
/>
</RelativeLayout>

2. list_chat.xml(layout文件下)

<?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"
    android:orientation="horizontal">

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

    <!-- 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:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

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

        <TextView
            android:id="@+id/txt_aSpeak"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="8px"
            android:textColor="#B4B4B9"
            android:textSize="14sp" />

    </LinearLayout>

3. 适配类

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;
    }
}

4. Viewholder

public class ViewHolder {
    public ImageView img_icon;
    public TextView txt_aName;
    public TextView txt_aSpeak;

    public ViewHolder ()
    {

    }
}

5. 继承BaseAdapter

public class ChatAdapter extends BaseAdapter {


    private LinkedList<Animal> mData;
    private Context mContext;

    public ChatAdapter(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) {
        ViewHolder holder = null;
        if(convertView == null){
            convertView = LayoutInflater.from(mContext).inflate(R.layout.list_chat,parent,false);
            holder = new ViewHolder();
            holder.img_icon =  convertView.findViewById(R.id.img_icon);
            holder.txt_aName = convertView.findViewById(R.id.txt_aName);
            holder.txt_aSpeak =  convertView.findViewById(R.id.txt_aSpeak);
            convertView.setTag(holder);   //将Holder存储到convertView中
        }else{
            holder = (ViewHolder) convertView.getTag();
        }
        holder.img_icon.setBackgroundResource(mData.get(position).getaIcon());
        holder.txt_aName.setText(mData.get(position).getaName());
        holder.txt_aSpeak.setText(mData.get(position).getaSpeak());
        return convertView;
    }

}

6. MainActivity类

public class MainActivity extends AppCompatActivity {
    private List<Animal> mData = null;
    private Context mContext;
    private ChatAdapter 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.list_animal);
        mData = new LinkedList<Animal>();
        mData.add(new Animal("狗说", "你是狗么?", R.drawable.show2));
        mData.add(new Animal("牛说", "你是牛么?", R.drawable.show2));
        mData.add(new Animal("鸭说", "你是鸭么?", R.drawable.show2));
        mData.add(new Animal("鱼说", "你是鱼么?", R.drawable.show2));
        mData.add(new Animal("马说", "你是马么?", R.drawable.show2));
        mAdapter = new ChatAdapter((LinkedList<Animal>) mData, mContext);
        list_animal.setAdapter(mAdapter);
    }
}