Android適配器之——BaseAdapter（例子）

1. public
   class RecentAdapter
   extends BaseAdapter {
   
2.  
3.     private
   class RecentViewHolder { 
   
4.         TextView appName; 
5. ImageView appIcon;
6.         TextView appSize; 
7.     } 
8.  
9.     private List<ResolveInfo> mAppList; 
   
10.     private LayoutInflater mInflater; 
    
11.     private PackageManager pm; 
    
12.  
13.     public RecentAdapter(Context c, List<ResolveInfo> appList, 
    
14.             PackageManager pm) { 
15.         mAppList = appList; 
16.         this.pm = pm; 
    
17.         mInflater = (LayoutInflater) c 
18.                 .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
19.     } 
20.      
21.     public
    void clear(){ 
    
22.         if(mAppList!=null){ 
    
23.             mAppList.clear(); 
24.         } 
25.     } 
26.  
27.     public
    int getCount() { 
    
28.         return mAppList.size(); 
    
29.     } 
30.  
31.     @Override 
32.     public Object getItem(int position) { 
    
33.         return mAppList.get(position); 
    
34.     } 
35.  
36.     @Override 
37.     public
    long getItemId(int position) { 
    
38.         // TODO Auto-generated method stub 
    
39.         return position; 
    
40.     } 
41.  
42.     public View getView(int position, View convertView, ViewGroup
    parent) { 
43.         RecentViewHolder holder; 
44.         if (convertView ==
    null) { 
    
45.             convertView = mInflater.inflate(R.layout.app_info_item,
    null); 
46.             holder = new RecentViewHolder(); 
    
47.             holder.appName = (TextView) convertView.findViewById(R.id.app_name); 
    
48.             holder.appIcon = (ImageView) convertView 
49.                     .findViewById(R.id.app_icon); 
50.             holder.appSize = (TextView) convertView.findViewById(R.id.app_size); 
    
51.             convertView.setTag(holder); 
52.         } else { 
    
53.             holder = (RecentViewHolder) convertView.getTag(); 
54.         } 
55.         ResolveInfo appInfo = mAppList.get(position); 
56.         if (appInfo !=
    null) { 
    
57.             String labelName = appInfo.loadLabel(pm).toString(); 
58.             if (labelName !=
    null) { 
    
59.                 holder.appName.setText(labelName); 
60.             } 
61.  
62.             Drawable icon = appInfo.loadIcon(pm); 
63.             if (icon !=
    null) { 
    
64.                 holder.appIcon.setImageDrawable(icon); 
65.             } 
66.         } 
67.         return convertView; 
    
68.     } 
69.      
70.     public
    void remove(int position){ 
    
71.         mAppList.remove(position); 
72.         this.notifyDataSetChanged(); 
    
73.     } 
74.  
75. } 

其中兩個注意點為：

setTag 用View設定儲存資料

notifyDataSetChanged() 告訴View資料更改並重新整理

View convertView = mInflater.inflate(R.layout.app_info_item, null)  載入XML Item 示圖

app_info_item.xml檔案樣本

 

 

1. <?xml version="1.0" encoding="utf-8"?> 
   
2.  
3. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   
4.     android:layout_width="fill_parent" android:layout_height="wrap_content" 
   
5.     android:layout_gravity="center_vertical" android:minHeight="?android:attr/listPreferredItemHeight"> 
   
6.  
7.     <ImageView android:id="@+id/app_icon" android:layout_width="@android:dimen/app_icon_size" 
   
8.         android:layout_height="@android:dimen/app_icon_size" 
   
9.         android:layout_alignParentLeft="true" android:paddingLeft="6dip" 
   
10.         android:paddingTop="6dip" android:paddingBottom="6dip" 
    
11.         android:scaleType="fitCenter" /> 
    
12.  
13.     <TextView android:id="@+id/app_name" android:layout_width="wrap_content" 
    
14.         android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceLarge" 
    
15.         android:textColor="?android:attr/textColorPrimary" 
    
16.         android:layout_toRightOf="@id/app_icon" android:paddingLeft="6dip" 
    
17.         android:paddingTop="6dip" /> 
    
18.  
19.     <TextView android:id="@+id/app_description" 
    
20.         android:layout_width="wrap_content" android:layout_height="wrap_content" 
    
21.         android:textAppearance="?android:attr/textAppearanceSmall" 
    
22.         android:layout_below="@+id/app_name" android:layout_toRightOf="@id/app_icon" 
    
23.         android:paddingLeft="6dip" android:paddingBottom="6dip" /> 
    
24.     <TextView android:id="@+id/app_size" android:layout_width="wrap_content" 
    
25.         android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceSmall" 
    
26.         android:layout_alignParentRight="true" android:layout_below="@+id/app_name" 
    
27.         android:paddingRight="6dip" android:maxLines="1" /> 
    
28.  
29. </RelativeLayout>