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 ListmContentList; 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 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 ListcontentList; 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 (); 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 ListmContentList; 21 private LayoutInflater mInflater; 22 private MyClickListener mListener; 23 24 public ContentAdapter(Context context, List 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 ListcontentList; 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 (); 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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