最近交流群里面有人问到一个问题：如何在Activity中响应ListView内部按钮的点击事件，不要在Adapter中响应？
对于这个问题，我最初给他的解答是，在Adapter中定义一个回调接口，在Activity中实现该接口，从而实现对点击事件的响应。
下班后思考了一下，觉得有两种方式都能比较好的实现：使用接口回调和使用抽象类回调。
正好可以复习一下接口和抽象类的区别，于是写了两个Demo：
1.使用接口回调：
Adapter类
1 package com.ivan.adapter;
2
3 import java.util.List;
4
5 import android.content.Context;
6 import android.util.Log;
7 import android.view.LayoutInflater;
8 import android.view.View;
9 import android.view.View.OnClickListener;
10 import android.view.ViewGroup;
11 import android.widget.BaseAdapter;
12 import android.widget.Button;
13 import android.widget.TextView;
14
15 import com.ivan.listvieweventcallback.R;
16
17 public class ContentAdapter extends BaseAdapter implements OnClickListener {
18
19 private static final String TAG = "ContentAdapter";
20 private List<String> mContentList;
21 private LayoutInflater mInflater;
22 private Callback mCallback;
23
24 /**
25 * 自定义接口，用于回调按钮点击事件到Activity
26 * @author Ivan Xu
27 * 2014-11-26
28 */
29 public interface Callback {
30 public void click(View v);
31 }
32
33 public ContentAdapter(Context context, List<String> contentList,
34 Callback callback) {
35 mContentList = contentList;
36 mInflater = LayoutInflater.from(context);
37 mCallback = callback;
38 }
39
40 @Override
41 public int getCount() {
42 Log.i(TAG, "getCount");
43 return mContentList.size();
44 }
45
46 @Override
47 public Object getItem(int position) {
48 Log.i(TAG, "getItem");
49 return mContentList.get(position);
50 }
51
52 @Override
53 public long getItemId(int position) {
54 Log.i(TAG, "getItemId");
55 return position;
56 }
57
58 @Override
59 public View getView(int position, View convertView, ViewGroup parent) {
60 Log.i(TAG, "getView");
61 ViewHolder holder = null;
62 if (convertView == null) {
63 convertView = mInflater.inflate(R.layout.list_item, null);
64 holder = new ViewHolder();
65 holder.textView = (TextView) convertView
66 .findViewById(R.id.textView1);
67 holder.button = (Button) convertView.findViewById(R.id.button1);
68 convertView.setTag(holder);
69 } else {
70 holder = (ViewHolder) convertView.getTag();
71 }
72 holder.textView.setText(mContentList.get(position));
73
74
75 holder.button.setOnClickListener(this);
76 holder.button.setTag(position);
77 return convertView;
78 }
79
80 public class ViewHolder {
81 public TextView textView;
82 public Button button;
83 }
84
85 //响应按钮点击事件,调用子定义接口，并传入View
86 @Override
87 public void onClick(View v) {
88 mCallback.click(v);
89 }
90 }
Activity类：
1 package com.ivan.listvieweventdemo;
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.view.View;
10 import android.widget.AdapterView;
11 import android.widget.AdapterView.OnItemClickListener;
12 import android.widget.ListView;
13 import android.widget.Toast;
14
15 import com.ivan.adapter.ContentAdapter;
16 import com.ivan.adapter.ContentAdapter.Callback;
17 import com.ivan.listvieweventcallback.R;
18 //MainActivity需要实现自定义接口
19 public class MainActivity extends Activity implements OnItemClickListener,
20 Callback {
21
22 // 模拟listview中加载的数据
23 private static final String[] CONTENTS = { "北京", "上海", "广州", "深圳", "苏州",
24 "南京", "武汉", "长沙", "杭州" };
25 private List<String> contentList;
26 private ListView mListView;
27
28 @Override
29 protected void onCreate(Bundle savedInstanceState) {
30 super.onCreate(savedInstanceState);
31 setContentView(R.layout.activity_main);
32
33 init();
34 }
35
36 private void init() {
37 mListView = (ListView) findViewById(R.id.listview);
38 contentList = new ArrayList<String>();
39 for (int i = 0; i < CONTENTS.length; i++) {
40 contentList.add(CONTENTS[i]);
41 }
42 //
43 mListView.setAdapter(new ContentAdapter(this, contentList, this));
44 mListView.setOnItemClickListener(this);
45 }
46
47 @Override
48 public boolean onCreateOptionsMenu(Menu menu) {
49 getMenuInflater().inflate(R.menu.main, menu);
50 return true;
51 }
52
53 /**
54 * 响应ListView中item的点击事件
55 */
56 @Override
57 public void onItemClick(AdapterView<?> arg0, View v, int position, long id) {
58 Toast.makeText(this, "listview的item被点击了！，点击的位置是-->" + position,
59 Toast.LENGTH_SHORT).show();
60 }
61
62 /**
63 * 接口方法，响应ListView按钮点击事件
64 */
65 @Override
66 public void click(View v) {
67 Toast.makeText(
68 MainActivity.this,
69 "listview的内部的按钮被点击了！，位置是-->" + (Integer) v.getTag() + ",内容是-->"
70 + contentList.get((Integer) v.getTag()),
71 Toast.LENGTH_SHORT).show();
72 }
73 }
2.使用抽象类回调
Adapter类：
1 package com.ivan.adapter;
2
3 import java.util.List;
4
5 import android.content.Context;
6 import android.util.Log;
7 import android.view.LayoutInflater;
8 import android.view.View;
9 import android.view.View.OnClickListener;
10 import android.view.ViewGroup;
11 import android.widget.BaseAdapter;
12 import android.widget.Button;
13 import android.widget.TextView;
14
15 import com.ivan.listvieweventabstract.R;
16
17 public class ContentAdapter extends BaseAdapter {
18
19 private static final String TAG = "ContentAdapter";
20 private List<String> mContentList;
21 private LayoutInflater mInflater;
22 private MyClickListener mListener;
23
24 public ContentAdapter(Context context, List<String> contentList,
25 MyClickListener listener) {
26 mContentList = contentList;
27 mInflater = LayoutInflater.from(context);
28 mListener = listener;
29 }
30
31 @Override
32 public int getCount() {
33 Log.i(TAG, "getCount");
34 return mContentList.size();
35 }
36
37 @Override
38 public Object getItem(int position) {
39 Log.i(TAG, "getItem");
40 return mContentList.get(position);
41 }
42
43 @Override
44 public long getItemId(int position) {
45 Log.i(TAG, "getItemId");
46 return position;
47 }
48
49 @Override
50 public View getView(int position, View convertView, ViewGroup parent) {
51 Log.i(TAG, "getView");
52 ViewHolder holder = null;
53 if (convertView == null) {
54 convertView = mInflater.inflate(R.layout.list_item, null);
55 holder = new ViewHolder();
56 holder.textView = (TextView) convertView
57 .findViewById(R.id.textView1);
58 holder.button = (Button) convertView.findViewById(R.id.button1);
59 convertView.setTag(holder);
60 } else {
61 holder = (ViewHolder) convertView.getTag();
62 }
63 holder.textView.setText(mContentList.get(position));
64 holder.button.setOnClickListener(mListener);
65 holder.button.setTag(position);
66 return convertView;
67 }
68
69 public class ViewHolder {
70 public TextView textView;
71 public Button button;
72 }
73
74 /**
75 * 用于回调的抽象类
76 * @author Ivan Xu
77 * 2014-11-26
78 */
79 public static abstract class MyClickListener implements OnClickListener {
80 /**
81 * 基类的onClick方法
82 */
83 @Override
84 public void onClick(View v) {
85 myOnClick((Integer) v.getTag(), v);
86 }
87 public abstract void myOnClick(int position, View v);
88 }
89 }
Activity类：
1 package com.ivan.listvieweventdemo;
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.view.View;
10 import android.widget.AdapterView;
11 import android.widget.AdapterView.OnItemClickListener;
12 import android.widget.ListView;
13 import android.widget.Toast;
14
15 import com.ivan.adapter.ContentAdapter;
16 import com.ivan.adapter.ContentAdapter.MyClickListener;
17 import com.ivan.listvieweventabstract.R;
18
19 public class MainActivity extends Activity implements OnItemClickListener {
20
21 // 模拟listview中加载的数据
22 private static final String[] CONTENTS = { "北京", "上海", "广州", "深圳", "苏州",
23 "南京", "武汉", "长沙", "杭州" };
24 private List<String> contentList;
25 private ListView mListView;
26
27 @Override
28 protected void onCreate(Bundle savedInstanceState) {
29 super.onCreate(savedInstanceState);
30 setContentView(R.layout.activity_main);
31
32 init();
33 }
34
35 private void init() {
36 mListView = (ListView) findViewById(R.id.listview);
37 contentList = new ArrayList<String>();
38 for (int i = 0; i < CONTENTS.length; i++) {
39 contentList.add(CONTENTS[i]);
40 }
41 //实例化ContentAdapter类，并传入实现类
42 mListView.setAdapter(new ContentAdapter(this, contentList, mListener));
43
44 mListView.setOnItemClickListener(this);
45 }
46
47 @Override
48 public boolean onCreateOptionsMenu(Menu menu) {
49 getMenuInflater().inflate(R.menu.main, menu);
50 return true;
51 }
52
53 //响应item点击事件
54 @Override
55 public void onItemClick(AdapterView<?> arg0, View v, int position, long id) {
56 Toast.makeText(this, "listview的item被点击了！，点击的位置是-->" + position,
57 Toast.LENGTH_SHORT).show();
58 }
59
60 /**
61 * 实现类，响应按钮点击事件
62 */
63 private MyClickListener mListener = new MyClickListener() {
64 @Override
65 public void myOnClick(int position, View v) {
66 Toast.makeText(
67 MainActivity.this,
68 "listview的内部的按钮被点击了！，位置是-->" + position + ",内容是-->"
69 + contentList.get(position), Toast.LENGTH_SHORT)
70 .show();
71 }
72 };
73 }
以下是布局文件
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 android:paddingBottom="@dimen/activity_vertical_margin"
6 android:paddingLeft="@dimen/activity_horizontal_margin"
7 android:paddingRight="@dimen/activity_horizontal_margin"
8 android:paddingTop="@dimen/activity_vertical_margin"
9 tools:context=".MainActivity" >
10
11 <ListView
12 android:id="@+id/listview"
13 android:layout_width="match_parent"
14 android:layout_height="match_parent" >
15 </ListView>
16
17 </RelativeLayout>
<?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="wrap_content"
android:descendantFocusability="blocksDescendants"
android:orientation="vertical" > <TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="content"
android:textColor="#ff0000"
android:textSize="20sp" /> <Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:focusable="false"
android:text="Button"
android:textColor="#ff0000"
android:textSize="20sp" /> </LinearLayout>
两种方式的区别在于，抽象类在Activity中实现的时候，只能定义一个成员变量来实现，不能由Activity直接实现，因为Java不支持多继承。而接口既可以由Activity直接实现，也可以由其成员变量来实现。
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