Android:Adapter笔记

Adapter:适配器-->将数据以什么形式发送到界面.

ΞBaseAdapter自定义及ListView的应用;

1.自定义BaseAdapter,重写其getView()方法;

ΞWife.java

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

    public Wife() {
    }

    public Wife(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;
    }
}

Ξ重写BaseAdapter;

public class WifeAdapter extends BaseAdapter {

    private LinkedList<Wife> mData; //ArrayList和LinkedList都是实现了List接口的容器类,进行查操作时用ArrayList，进行增删操作的时候最好用LinkedList。
    private Context mContext;

    public WifeAdapter(LinkedList<Wife> 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) { 　　//重写geiView()
    ViewHolder holder = null;
    if(convertView == null){　　　　　　　　　　　　　　//由于会多次调用getView(),所以在此处判断,只需调用一次生成函数体(包括inflate()和findViewById())即可
        convertView = LayoutInflater.from(mContext).inflate(R.layout.list_item_wife,parent,false);
        holder = new ViewHolder();
        holder.img_icon = (ImageView) convertView.findViewById(R.id.img_icon);
        holder.txt_aName = (TextView) convertView.findViewById(R.id.txt_aName);
        holder.txt_aSpeak = (TextView) convertView.findViewById(R.id.txt_aSpeak);
        convertView.setTag(holder);   //将Holder存储到convertView中,setTag（Onbect）表示给View添加一个格外的数据，以后可以用getTag()将这个数据取出来。
    }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;
}

static class ViewHolder{
    ImageView img_icon;
    TextView txt_aName;
    TextView txt_aSpeak;
}
}

ΞViewHolder是你自己造出来的一个类,配合convertView减少调用findViewById()的次数;

2.编写ListView;

mainActivity.java

public class MainActivity extends AppCompatActivity {

    private List<Wife> mData = null;
    private Context mContext;
    private WifeAdapter mAdapter = null;
    private ListView list_wife;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = MainActivity.this;
        list_wife = (ListView) findViewById(R.id.list_wife);
        mData = new LinkedList<Wife>(); 　　　　//添加元素
        mData.add(new Wife("椎名真白", "呐,你想变成什么颜色?", R.drawable.hina));
        mData.add(new Wife("泽村英梨梨", "都说了我没生气!", R.drawable.ilili));
        mData.add(new Wife("加藤惠", "老公~", R.drawable.megumi));
        mAdapter = new WifeAdapter((LinkedList<Wife>) mData, mContext);
        list_wife.setAdapter(mAdapter);
    }

}

list_item_wife.xml

<?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">



    <ImageView
        android:id="@+id/img_icon"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:baselineAlignBottom="true"
        android:paddingLeft="8dp"/>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        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="25sp"/>

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




    </LinearLayout>


    <!--<ListView-->
        <!--android:id="@+id/listview"-->
        <!--android:layout_width="match_parent"-->
        <!--android:layout_height="match_parent">-->

    <!--</ListView>-->

</LinearLayout>

activity_main.xml

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


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



</android.support.constraint.ConstraintLayout>

3.效果图;