（一）原本java的写法（相信很多是学过java的）：
需要实现接口View.IOnClickListener，最好也继承类：Activity，因为View.IOnClickListener接口又继承了IJavaObject, IDisposable接口，所以还学要实现这两个接口里面的成员，而Activity已经实现可了这两个接口的成员，就不需要我们再写了，毕竟我们大部分只想重写View.IOnClickListener里面的OnClick函数。（如果自定义的类只是实现了View.IOnClickListener接口，不继承Activity，就需要实现另外2个接口的其他成员，在vs中选中接口，使用快捷键Alt+Shift+F10，可快速实现接口）
代码如下：
1 using System;
2 using Android.App;
3 using Android.Content;
4 using Android.Runtime;
5 using Android.Views;
6 using Android.Widget;
7 using Android.OS;
8
9 namespace App2
10 {
11 [Activity(Label = "App2", MainLauncher = true, Icon = "@drawable/icon")]
12
13
14 public class MainActivity : Activity, View.IOnClickListener
15 {
16 Button button;
17 public void OnClick(View v)
18 {
19 button.Text = string.Format("{0} clicks!", v.Id);
20 }
21 protected override void OnCreate(Bundle bundle)
22 {
23 base.OnCreate(bundle);
24
25 // Set our view from the "main" layout resource
26 SetContentView(Resource.Layout.Main);
27
28 // Get our button from the layout resource,
29 // and attach an event to it
30 button = FindViewById<Button>(Resource.Id.MyButton);
31 button.SetOnClickListener(this);
32
33 }
34 }
35 }
当然也可以自己定义一个类，实现接口，重写OnClick函数，然后button.SetOnClickListener(你自定义类的实例);
（二）接下来介绍C#的4种写法（其实大同小异）
1.第一种（创建模板就有的）：
1 Button button = FindViewById<Button>(Resource.Id.MyButton);
2 button.Click += delegate { button.Text = string.Format ("{0} clicks!", count++);};
2.第二种
1 namespace App2
2 {
3 [Activity(Label = "App2", MainLauncher = true, Icon = "@drawable/icon")]
4
5
6 public class MainActivity : Activity, View.IOnClickListener
7 {
8 int count = 1;
9 Button button;
10
11 protected override void OnCreate(Bundle bundle)
12 {
13 base.OnCreate(bundle);
14
15 // Set our view from the "main" layout resource
16 SetContentView(Resource.Layout.Main);
17
18 // Get our button from the layout resource,
19 // and attach an event to it
20 button = FindViewById<Button>(Resource.Id.MyButton);
21 button.Click +=button_Click;
22
23 }
24
25 private void button_Click(object sender, EventArgs e)
26 {
27 button.Text = string.Format("{0} clicks!", count++);
28 }
29
30
31 }
32 }
3.第三种
1 public class MainActivity : Activity, View.IOnClickListener
2 {
3 int count = 1;
4 Button button;
5
6 protected override void OnCreate(Bundle bundle)
7 {
8 base.OnCreate(bundle);
9
10 // Set our view from the "main" layout resource
11 SetContentView(Resource.Layout.Main);
12
13 // Get our button from the layout resource,
14 // and attach an event to it
15 button = FindViewById<Button>(Resource.Id.MyButton);
16 button.Click += new EventHandler(button_Click);
17
18 }
19
20 private void button_Click(object sender, EventArgs e)
21 {
22 button.Text = string.Format("{0} clicks!", count++);
23 }
24
25
26 }
4.第四种
1 namespace App2
2 {
3 [Activity(Label = "App2", MainLauncher = true, Icon = "@drawable/icon")]
4
5
6 public class MainActivity : Activity, View.IOnClickListener
7 {
8 int count = 1;
9 Button button;
10
11 protected override void OnCreate(Bundle bundle)
12 {
13 base.OnCreate(bundle);
14
15 // Set our view from the "main" layout resource
16 SetContentView(Resource.Layout.Main);
17
18 // Get our button from the layout resource,
19 // and attach an event to it
20 button = FindViewById<Button>(Resource.Id.MyButton);
21 button.Click += (sender, e) =>{ button.Text = string.Format ("{0} clicks!", count++);};
22
23 }
24 }
25 }