各司其职：在Android适配器中使用委托者模式

 1 package com.change.delegateforadapterdemo;
 2 
 3 import java.util.List;
 4 
 5 import android.content.Context;
 6 import android.view.LayoutInflater;
 7 import android.view.View;
 8 import android.view.View.OnClickListener;
 9 import android.view.ViewGroup;
10 import android.widget.BaseAdapter;
11 import android.widget.Button;
12 import android.widget.TextView;
13 
14 /**
15  * 委托者模式运用在adapter中
16  * @author Change
17  *
18  */
19 public class DelegateForAdapter extends BaseAdapter {
20     private List<String> names;
21     private LayoutInflater mInflater;
22     private DataControlDelegate mDelegate;
23     public DelegateForAdapter(Context ctx,List<String> _names) {
24         this.names = _names;
25         mInflater = LayoutInflater.from(ctx);
26     }
27     /**
28      * 委托接口，用于对adapter中的数据进行操作，此处只提供了一个删除单条数据的方法。
29      * @author Change
30      *
31      */
32     public static interface DataControlDelegate{
33         /**
34          * 删除数据
35          * @param name
36          */
37         public void removeItem(String name);
38     }
39     
40     @Override
41     public int getCount() {
42         return names.size();
43     }
44 
45     @Override
46     public Object getItem(int arg0) {
47         return names.get(arg0);
48     }
49 
50     @Override
51     public long getItemId(int arg0) {
52         return arg0;
53     }
54 
55     @Override
56     public View getView(int arg0, View arg1, ViewGroup arg2) {
57         ViewHolder holder = null;
58         if(null==arg1){
59             arg1 = mInflater.inflate(R.layout.item_name, null);
60             holder = new ViewHolder();
61             holder.name = (TextView)arg1.findViewById(R.id.name);
62             holder.remove = (Button)arg1.findViewById(R.id.remove);
63             arg1.setTag(holder);
64         }else{
65             holder = (ViewHolder)arg1.getTag();
66         }
67         final String name = names.get(arg0);
68         holder.remove.setOnClickListener(new OnClickListener() {
69             @Override
70             public void onClick(View arg0) {
71                 if(null!=mDelegate)
72                     mDelegate.removeItem(name);//删除行为
73             }
74         });
75         holder.name.setText(name);
76         return arg1;
77     }
78     static class ViewHolder{
79         public TextView name;
80         public Button remove;
81     }
82     /**
83      * 设置委托者
84      * @param _delegate
85      */
86     public void setDataControlDelegate(DataControlDelegate _delegate){
87         this.mDelegate = _delegate;
88     }
89 
90 }

 1 package com.change.delegateforadapterdemo;
 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.view.Menu;
 9 import android.widget.ListView;
10 import android.widget.Toast;
11 
12 import com.change.delegateforadapterdemo.DelegateForAdapter.DataControlDelegate;
13 
14 /**
15  * 实现adapter中的数据委托接口，把所有的行为让activity来控制吧。
16  * @author Change
17  *
18  */
19 public class MainActivity extends Activity implements DataControlDelegate{
20     private List<String> names = new ArrayList<String>();
21     private DelegateForAdapter adapter;
22     @Override
23     protected void onCreate(Bundle savedInstanceState) {
24         super.onCreate(savedInstanceState);
25         setContentView(R.layout.activity_main);
26         initDatas();
27         ListView lv = (ListView)findViewById(R.id.lv);
28         adapter = new DelegateForAdapter(this, names);
29         adapter.setDataControlDelegate(this);
30         lv.setAdapter(adapter);
31     }
32 
33     @Override
34     public boolean onCreateOptionsMenu(Menu menu) {
35         // Inflate the menu; this adds items to the action bar if it is present.
36         getMenuInflater().inflate(R.menu.main, menu);
37         return true;
38     }
39     
40     private void initDatas(){
41         for(int i=0;i<10;i++){
42             names.add("name"+i);
43         }
44     }
45 
46     @Override
47     public void removeItem(String name) {
48         names.remove(name);
49         adapter.notifyDataSetChanged();
50         Toast.makeText(this, "已删除"+name, Toast.LENGTH_SHORT).show();
51     }
52 
53 }