第二课 两个视图+数据传输

项目结构如下图：

比第一课多了一个活动（Activity）。

1.Activity1.cs代码如下：

using System;

using Android.App;

using Android.Content;

using Android.Runtime;

using Android.Views;

using Android.Widget;

using Android.OS;

using Android.Util;

namespace MyLesson

{

    [Activity(Label = "Lesson2_View1", MainLauncher = true, Icon = "@drawable/icon")]

    public class Lesson21 : Activity

    {

        protected override void OnCreate(Bundle bundle)

        {

            base.OnCreate(bundle);

            LinearLayout layout = new LinearLayout(this);

            layout.Orientation = Orientation.Vertical;

            TextView tv = new TextView(this);

            tv.Text = "这是第一个视图";

            Button b = new Button(this);

            b.Text = "点击切换到第二个视图";

            b.Click += b_Click;

            layout.AddView(tv);

            layout.AddView(b);

            SetContentView(layout);

        }

        void b_Click(object sender, EventArgs e)

        {

            Intent intent = new Android.Content.Intent(this, typeof(Lesson22));

            intent.PutExtra("MessageName", "你好，这里是视图1");

            StartActivity(intent);

        }

    }

}

2.Activity2.cs代码如下：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using Android.App;

using Android.Content;

using Android.OS;

using Android.Runtime;

using Android.Views;

using Android.Widget;

namespace MyLesson

{

    [Activity(Label = "Lesson2_view2")]

    public class Lesson22 : Activity

    {

        protected override void OnCreate(Bundle bundle)

        {

            base.OnCreate(bundle);

            LinearLayout layout = new LinearLayout(this);

            layout.Orientation = Orientation.Vertical;

            TextView tv = new TextView(this);

            tv.Text = "这是第二个视图，来自第一个视图的数据是：" + (Intent.GetStringExtra("MessageName") ?? "没说什么");

            layout.AddView(tv);

            SetContentView(layout);

        }

    }

}