Activity 之间 Intent 传值

使用PutExtra()发送数据，GetStringExtra()接收数据，??空合并运算符做兜底默认值。

1、主页面布局 activity_main.axml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!--注意id：@+id/edittext -->
    <EditText
        android:id="@+id/edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="请输入内容"/>

    <Button
        android:text="提交"
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>Code language: HTML, XML (xml)

2、第二个页面布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!--接收数据展示，id:textview1-->
    <TextView
        android:id="@+id/textview1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <Button
        android:text="返回首页"
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>Code language: HTML, XML (xml)

3、MainActivity.cs 发送数据页面

using Android.App;
using Android.OS;
using Android.Widget;
using Android.Content;

namespace TestPass
{
    [Activity(Label = "MainActivity")]
    public class MainActivity : Activity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.activity_main);

            //绑定按钮点击事件
            Button button = FindViewById<Button>(Resource.Id.button1);
            button.Click += Button_Click;
        }

        private void Button_Click(object sender, EventArgs e)
        {
            //1. 创建Intent，跳转至SecondScreen
            var second = new Intent(this, typeof(SecondScreen));

            //2. PutExtra传递字符串，key="name"
            string inputText = FindViewById<EditText>(Resource.Id.edittext).Text;
            second.PutExtra("name", inputText);

            //3. 启动第二个Activity
            StartActivity(second);
        }
    }
}Code language: HTML, XML (xml)

4、SecondScreen.cs 接收数据页面

using Android.App;
using Android.OS;
using Android.Widget;
using Android.Content;

namespace TestPass
{
    [Activity(Label = "SecondScreen")]
    public class SecondScreen : Activity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.content_main);

            //接收Intent传递过来的数据 并且给控件赋值
            // ?? "出现错误"：如果拿到null，就显示兜底文本
            FindViewById<TextView>(Resource.Id.textview1).Text 
                = Intent.GetStringExtra("name") ?? "出现错误";

            //返回首页按钮
            Button button = FindViewById<Button>(Resource.Id.button1);
            button.Click += Button_Click;
        }

        private void Button_Click(object sender, EventArgs e)
        {
            //回到主页面
            StartActivity(typeof(MainActivity));
        }
    }
}Code language: HTML, XML (xml)