适配器的经典写法

有关ListView优化机制及滑动时数据错乱问题的讨论


class GridViewAdapter extends BaseAdapter{

        LayoutInflater inflater;
        List<PackageInfo> pkInfos;
        public GridViewAdapter(Context context,List<PackageInfo> packageInfos) {
            inflater = LayoutInflater.from(context);
            this.pkInfos = packageInfos;
        }
        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return pkInfos.size();
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return pkInfos.get(position);
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub
        
                View view = inflater.inflate(R.layout.gv_item, null);
                TextView tv = (TextView)view.findViewById(R.id.gv_item_appname);
                ImageView iv = (ImageView)view.findViewById(R.id.gv_item_icon);
                tv.setText(pkInfos.get(position).applicationInfo.loadLabel(getPackageManager()));
                iv.setImageDrawable(pkInfos.get(position).applicationInfo.loadIcon(getPackageManager()));
                
            return view;
        }
        
    }

适配器的经典写法

 1 class ListViewAdapter extends BaseAdapter{
 2 
 3         LayoutInflater inflater;
 4         List<PackageInfo> pkInfos;
 5         public ListViewAdapter(Context context,List<PackageInfo> packageInfos) {
 6             inflater = LayoutInflater.from(context);
 7             this.pkInfos = packageInfos;
 8         }
 9         @Override
10         public int getCount() {
11             // TODO Auto-generated method stub
12             return pkInfos.size();
13         }
14 
15         @Override
16         public Object getItem(int position) {
17             // TODO Auto-generated method stub
18             return pkInfos.get(position);
19         }
20 
21         @Override
22         public long getItemId(int position) {
23             // TODO Auto-generated method stub
24             return position;
25         }
26 
27         @Override
28         public View getView(int position, View convertView, ViewGroup parent) {
29             // TODO Auto-generated method stub
30         
31                 View view = inflater.inflate(R.layout.lv_item, null);
32                 TextView ntv = (TextView)view.findViewById(R.id.lv_item_appname);
33                 TextView ptv = (TextView)view.findViewById(R.id.lv_item_packagename);
34                 ImageView iv = (ImageView)view.findViewById(R.id.lv_icon);
35                 ntv.setText(pkInfos.get(position).packageName);
36                 ptv.setText(pkInfos.get(position).applicationInfo.loadLabel(getPackageManager()));
37                 iv.setImageDrawable(pkInfos.get(position).applicationInfo.loadIcon(getPackageManager()));
38                 
39             return view;
40         }
41         
42     }

适配器的经典写法

尽量自己构建适配器，这样加载速度快，效率高。哪怕简单的也尽量不要使用SimpleAdapter

view holder的用法：

<?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" >

    <TextView
        android:id="@+id/userinfo1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_weight="4" />

    <TextView
        android:id="@+id/userinfo2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="2" />

    <TextView
        android:id="@+id/userinfo3"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="4" />

    <TextView
        android:id="@+id/userinfo4"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="3" />

    <TextView
        android:id="@+id/userinfo5"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginRight="10dp"
        android:layout_weight="3" />

</LinearLayout>

View Code