制作listView高效率万能适配器

Posted 2020-06-13

 

　　　　本案例学习来自 _鸿洋_ 大神,自己在写一遍,加深记忆http://blog.csdn.net/lmj623565791/article/details/38902805  

 

 

我们都是以前写listView  都是这个样子

 1 package com.example.listviewdemo;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 import android.app.Activity;
 7 import android.os.Bundle;
 8 import android.widget.ListView;
 9 
10 public class MainActivity extends Activity {
11 
12     private ListView lv ;
13     private List<String> list = new ArrayList<String>();
14     
15     @Override
16     protected void onCreate(Bundle savedInstanceState) {
17         super.onCreate(savedInstanceState);
18         setContentView(R.layout.activity_main);
19         initData();
20         lv = (ListView) findViewById(R.id.id_main_lv);
21         MyAdapter<String> adapter = new MyAdapter<String>(list,this);
22         lv.setAdapter(adapter);
23     }
24 
25     private void initData() {
26         for(int i=0;i<30;i++){
27             list.add("qqqqq"+i);
28         }
29     }
30 
31     
32 }

 

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     >
 6 
 7     <ListView
 8         android:id="@+id/id_main_lv"
 9         android:layout_width="wrap_content"
10         android:layout_height="wrap_content"
11         android:text="@string/hello_world" />
12 
13 </RelativeLayout>

 

 1 package com.example.listviewdemo;
 2 
 3 import java.util.List;
 4 
 5 import android.content.Context;
 6 import android.view.View;
 7 import android.view.ViewGroup;
 8 import android.widget.BaseAdapter;
 9 import android.widget.TextView;
10 
11 public class MyAdapter<T> extends BaseAdapter {
12 
13     private List<T> list;
14     private Context mContext;
15     public MyAdapter(List<T> list,Context mContext) {
16         super();
17         this.list = list;
18         this.mContext = mContext;
19     }
20 
21     
22     @Override
23     public int getCount() {
24         // TODO Auto-generated method stub
25         return list.size();
26     }
27 
28     @Override
29     public Object getItem(int position) {
30         // TODO Auto-generated method stub
31         return list.get(position);
32     }
33 
34     @Override
35     public long getItemId(int position) {
36         // TODO Auto-generated method stub
37         return position;
38     }
39 
40     @Override
41     public View getView(int position, View convertView, ViewGroup parent) {
42         
43         ViewHolder holder = null;
44         if(convertView == null){
45             holder = new ViewHolder();
46             convertView = View.inflate(mContext, R.layout.item_listview, null);
47             holder.tv = (TextView) convertView.findViewById(R.id.item_tv);
48             convertView.setTag(holder);
49         }else{
50             holder  =    (ViewHolder) convertView.getTag();
51         }
52         holder.tv.setText((String)list.get(position));
53         System.out.println((String)list.get(position));
54         return convertView;
55     }
56 
57      class ViewHolder{
58          TextView tv ;
59     }
60 }

 

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:layout_gravity="center"
 6     android:orientation="vertical" >
 7 
 8     <TextView
 9         android:id="@+id/item_tv"
10         android:textSize="15sp"
11          android:layout_width="wrap_content"
12         android:layout_height="wrap_content"/>
13 
14 </LinearLayout>