Update samples to .NET 7

Besides simply changing `$(TargetFramwork)` to `net7.0-android`...

We also can use `RequireViewById` for better C# nullability checks.

Author: jonathanpeppers

AIDLDemo/AIDLDemo/AIDLDemo.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net6.0-android</TargetFramework>
+    <TargetFramework>net7.0-android</TargetFramework>
     <SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>
     <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>

AIDLDemo/AIDLDemo/Activity1.cs

@@ -17,9 +17,7 @@ protected override void OnStart ()
 		base.OnStart ();
 		InitService ();
 
-		var button1 = FindViewById<Button> (Resource.Id.buttonCalc);
-		ArgumentNullException.ThrowIfNull(button1, nameof (button1));
-
+		var button1 = RequireViewById<Button> (Resource.Id.buttonCalc);
 		button1.Click += (sender, e) => {
 			if (Service != null) {
 				var text1 = FindViewById<EditText> (Resource.Id.value1);

ActivityLifecycle/ActivityLifecycle.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net6.0-android</TargetFramework>
+    <TargetFramework>net7.0-android</TargetFramework>
     <SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>
     <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>

ActivityLifecycle/MainActivity.cs

@@ -17,32 +17,26 @@ protected override void OnCreate(Bundle? bundle)
         base.OnCreate(bundle);
         SetContentView(Resource.Layout.activity_main);
 
-        var button = FindViewById<Button>(Resource.Id.myButton);
-        if (button != null)
+        var button = RequireViewById<Button>(Resource.Id.myButton);
+        button.Click += (sender, args) =>
         {
-            button.Click += (sender, args) =>
-            {
-                var intent = new Intent(this, typeof(SecondActivity));
-                StartActivity(intent);
-            };
-        }
+            var intent = new Intent(this, typeof(SecondActivity));
+            StartActivity(intent);
+        };
 
         if (bundle != null)
         {
             _counter = bundle.GetInt("click_count", 0);
             Log.Debug(GetType().FullName, "Activity A - Recovered instance state");
         }
 
-        var clickbutton = FindViewById<Button>(Resource.Id.clickButton);
-        if (clickbutton != null)
+        var clickbutton = RequireViewById<Button>(Resource.Id.clickButton);
+        clickbutton.Text = Resources?.GetString(Resource.String.counterbutton_text, _counter);
+        clickbutton.Click += (sender, args) =>
         {
+            _counter++;
             clickbutton.Text = Resources?.GetString(Resource.String.counterbutton_text, _counter);
-            clickbutton.Click += (sender, args) =>
-            {
-                _counter++;
-                clickbutton.Text = Resources?.GetString(Resource.String.counterbutton_text, _counter);
-            };
-        }
+        };
     }
 
     protected override void OnSaveInstanceState(Bundle outState)

Button/Button/Button.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net6.0-android</TargetFramework>
+    <TargetFramework>net7.0-android</TargetFramework>
     <SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>
     <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>

README.md

@@ -1,16 +1,16 @@
 # MonoDroid (Xamarin.Android) samples
 
-This branch contains samples ported to .NET 6.
+This branch contains samples ported to .NET 7.
 
 See the [.NET MAUI Installation docs](https://docs.microsoft.com/en-us/dotnet/maui/get-started/installation) for setup instructions.
 
 This repository contains Mono for Android samples, showing usage of various
 Android API wrappers from C#. Visit the [Android Sample Gallery](https://docs.microsoft.com/samples/browse/?term=Xamarin.Android)
 to download individual samples.
 
-## Tips for .NET 6 Migration
+## Tips for .NET 7 Migration
 
-The goal here is to fully "modernize" the template for .NET 6 and C# 10.
+The goal here is to fully "modernize" the template for .NET 7 and C# 11.
 
 Compare a `dotnet new android` template named the same as the existing project.
 

TextSwitcher/TextSwitcher/MainActivity.cs

@@ -14,8 +14,7 @@ protected override void OnCreate(Bundle? savedInstanceState)
             SetContentView(Resource.Layout.Main);
 
             // Get the TextSwitcher view from the layout
-            var mSwitcher = FindViewById<Android.Widget.TextSwitcher>(Resource.Id.switcher);
-            ArgumentNullException.ThrowIfNull(mSwitcher);
+            var mSwitcher = RequireViewById<Android.Widget.TextSwitcher>(Resource.Id.switcher);
 
             // BEGIN_INCLUDE(setup)
             // Set the factory used to create TextViews to switch between.
@@ -36,9 +35,7 @@ protected override void OnCreate(Bundle? savedInstanceState)
 	         * the new value is displayed in the TextSwitcher. The change of text is
 	         * automatically animated using the in/out animations set above.
 	         */
-            var nextButton = FindViewById<Button>(Resource.Id.button);
-            ArgumentNullException.ThrowIfNull(nextButton);
-
+            var nextButton = RequireViewById<Button>(Resource.Id.button);
             nextButton.Click += (sender, e) =>
             {
                 mCounter++;

TextSwitcher/TextSwitcher/TextSwitcher.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net6.0-android</TargetFramework>
+    <TargetFramework>net7.0-android</TargetFramework>
     <SupportedOSPlatformVersion>23</SupportedOSPlatformVersion>
     <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>