Mono for android，Xamarin点击事件的多种写法

（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 }