Android custom ListView-javaTutorial-php.cn

Android custom ListView

高洛峰

Release： 2016-12-13 17:01:03

Original

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This article talks about implementing a custom list Android program. The program will implement a ListView that uses a custom adapter to bind
data and bind data with buttons through contextView.setTag.
When the system displays a list (ListView), it will first instantiate an adapter. This article will instantiate a custom adapter. To implement a custom adapter, you must manually map data. In this case, you need to override the getView() method. The system will call this method when drawing each row of the list.
When the ListView starts drawing, the system automatically calls the getCount() function, and obtains the length of the ListView based on the function return value.
Then based on this length, it calls getView() to draw each line one by one.
You can refer to the following code for specific usage. Just remember the three steps of Android custom ListView:
Step 1: Prepare main layout file, component layout file, etc.
Step 2: Obtain and organize data
Part 3: Binding Data, here we complete it by writing the Adapter class ourselves
1. First create a new list. Usage: The LayoutInflater class is still very useful in actual development. Its function is similar to findViewById(). The difference is that LayoutInflater is used to find the xml layout file under the layout and instantiate it! .
The three parameters of getView(): position indicates which row will be displayed, covertView is the layout inflated from the layout file
. We use the LayoutInflater method to extract the defined list.xml file into a View instance for display. Then instantiate each component in the xml file

, so that the data can be mapped to each component. But in order to respond to the click event, the button needs to add a click listener to it, so that the click event can be captured.

3. Add ListView control in activity_main.xml

Java code

<?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="vertical" >  
    <LinearLayout android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:orientation="horizontal" android:background="#f1e4f1">  
        <ImageView   
            android:id="@+id/image"  
            android:layout_width="wrap_content"  
            android:layout_height="wrap_content"/>  
        <TextView   
            android:id="@+id/title"  
            android:layout_width="wrap_content"  
            android:layout_height="wrap_content"  
            android:textColor="#666872"/>  
        <Button   
            android:id="@+id/view"  
            android:layout_width="wrap_content"  
            android:layout_height="wrap_content"  
            android:text="详细"/>  
    </LinearLayout>  
    <TextView   
        android:id="@+id/info"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:textColor="#666872"/>  
</LinearLayout>

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4. Call ListView in activity

Java code

public class MyAdspter extends BaseAdapter {  
  
    private List<Map<String, Object>> data;  
    private LayoutInflater layoutInflater;  
    private Context context;  
    public MyAdspter(Context context,List<Map<String, Object>> data){  
        this.context=context;  
        this.data=data;  
        this.layoutInflater=LayoutInflater.from(context);  
    }  
    /** 
     * 组件集合，对应list.xml中的控件 
     * @author Administrator 
     */  
    public final class Zujian{  
        public ImageView image;  
        public TextView title;  
        public Button view;  
        public TextView info;  
    }  
    @Override  
    public int getCount() {  
        return data.size();  
    }  
    /** 
     * 获得某一位置的数据 
     */  
    @Override  
    public Object getItem(int position) {  
        return data.get(position);  
    }  
    /** 
     * 获得唯一标识 
     */  
    @Override  
    public long getItemId(int position) {  
        return position;  
    }  
  
    @Override  
    public View getView(int position, View convertView, ViewGroup parent) {  
        Zujian zujian=null;  
        if(convertView==null){  
            zujian=new Zujian();  
            //获得组件，实例化组件  
            convertView=layoutInflater.inflate(R.layout.list, null);  
            zujian.image=(ImageView)convertView.findViewById(R.id.image);  
            zujian.title=(TextView)convertView.findViewById(R.id.title);  
            zujian.view=(Button)convertView.findViewById(R.id.view);  
            zujian.info=(TextView)convertView.findViewById(R.id.info);  
            convertView.setTag(zujian);  
        }else{  
            zujian=(Zujian)convertView.getTag();  
        }  
        //绑定数据  
        zujian.image.setBackgroundResource((Integer)data.get(position).get("image"));  
        zujian.title.setText((String)data.get(position).get("title"));  
        zujian.info.setText((String)data.get(position).get("info"));  
        return convertView;  
    }  
  
}

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