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Xamarin.Android 10.3 release notes

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What's new in Xamarin.Android 10.3

Xamarin.Android 10.3 releases

Corresponding Visual Studio 2019 release notes

June 1 and 2, 2020 — Xamarin.Android 10.3.1.4

This version is included in the Visual Studio 2019 version 16.6.1 release and in the Stable updater channel of Visual Studio 2019 for Mac version 8.6.2.

Issues fixed in Xamarin.Android 10.3.1.4

Application and library build and deployment

  • Developer Community 955972 Starting in Xamarin.Android 10.3, error APT2258: not well-formed (invalid token) prevented using accented characters or other non-ASCII UTF-8 characters in Android layout files that also contained custom views.
  • Developer Community 955972 Starting in Xamarin.Android 10.3, errors similar to error XARLC7000: System.Xml.XmlException: Invalid character in the given encoding could prevent successful builds for certain project configurations, such as projects located in directory paths that contained accented characters or other non-ASCII UTF-8 characters.

Application behavior on device and emulator

  • Developer Community 1021788: GitHub 4727: Starting in Xamarin.Android 10.3, many typemap: unable to find mapping to a Java type from managed type messages were logged to the application output for running apps, in some cases causing Visual Studio to become unresponsive until the output window caught up.
  • Developer Community 1030901, GitHub 4664: Starting in Xamarin.Android 10.3, localized resources from .resx files were no longer deployed when building and deploying from within Visual Studio to an attached device or emulator. (In contrast, clean builds on the command line worked as expected.)

May 19, 2020 — Xamarin.Android 10.3.1.0

This version is included in the Visual Studio 2019 version 16.6 release and in the Stable updater channel of Visual Studio 2019 for Mac version 8.6.

In Xamarin.Android 10.3.1.0

Deprecations, removals, and default configuration changes

Build and deployment performance

  • GitHub PR 3885: Adjust caching of device information during the build so it covers the case where no device or emulator is found. This reduced the time for the DetectIfAppWasUninstalled task from about 2 seconds to about 0 seconds, bringing the total time down closer to the time for a build where a device or emulator is available.
  • GitHub PR 3999: Allow BuildApk to merge new files into the previous APK instead of generating a new APK from scratch for incremental builds where an Android resource file has changed. This reduced the incremental build time for the BuildApk step from about 4 seconds to about 0.7 seconds for a small test app when one Android resource file was changed between builds.
  • GitHub PR 4158: Update the default order of strategies used to detect installed packages to minimize time for modern devices. This can potentially save about 100 milliseconds for the first deployment of an app after launching Visual Studio.
  • GitHub PR 4215: Remove a redundant call to the ResolveAssemblyReference task during the _ResolveSatellitePaths target. This reduced the total time spent in calls to ResolveAssemblyReference from about 240 milliseconds to about 150 milliseconds for incremental builds of a medium sized project. The same savings also apply to the deployment step, resulting in an approximate combined savings of 180 milliseconds for build and deployment of the test project.
  • GitHub PR 4236: Use a Lazy<T> type to access the NuGet lock file so it is only loaded when needed, and remove some redundant logging messages. This reduced the total time for the ResolveAssemblies task from about 320 milliseconds to about 240 milliseconds for incremental builds of a medium sized project. The same savings also apply to the deployment step, resulting in an approximate combined savings of 160 milliseconds for build and deployment of the test project.
  • GitHub PR 4251: Reuse MemoryStream instances throughout the Xamarin.Android build targets to save on allocations. This reduced the combined time for the _GenerateJavaStubs, _ResolveLibraryProjectImports, and _GeneratePackageManagerJava targets from about 3.3 seconds to about 3.0 seconds for an incremental build of a test app where the MainActivity type was modified between builds.
  • GitHub PR 4260: Remove unneeded calls to string.Format() during the LinkAssembliesNoShrink task. This reduced the time for the task from about 800 milliseconds to about 770 milliseconds for an initial clean build of a small Xamarin.Forms test app.
  • GitHub PR 4268, Java.Interop GitHub PR 570: Implement and switch to a new set of wrapper methods around the Mono.Cecil methods to allow caching the results during the GenerateJavaStubs task. This reduced the time for the task from about 1.4 seconds to about 0.9 seconds for an initial clean build of small test Xamarin.Forms test app.
  • GitHub PR 4303: Replace string interpolation during typemap assembly code generation in GenerateJavaStubs with sequential calls to StreamWriter.Write(). This reduced the total time for GenerateJavaStubs from about 1.3 seconds to about 0.9 seconds for an initial clean build of a small Xamarin.Forms test app.
  • GitHub PR 4308: Skip executing keytool -list during the SignAndroidPackage target. This saved about 200 milliseconds for the SignAndroidPackage target for incremental builds where a new APK was generated, such as after changing an Android resource.
  • GitHub PR 4316: Switch the LinkAssembliesNoShrink task to take advantage of the caching from the new Mono.Cecil wrapper methods introduced in Java.Interop GitHub PR 570. This reduced the time for the task from about 710 milliseconds to about 700 milliseconds for an initial clean build of a small Xamarin.Forms test app.
  • GitHub PR 4320: Update the version of LibZipSharp used by the build tasks to 1.0.10, which switches several byte[] instances to System.Buffers.ArrayPool instances to save on allocations. This reduced the combined time for the ResolveLibraryProjectImports and BuildApk tasks from about 5.3 seconds to about 5.0 seconds for a small test Xamarin.Forms app on an initial clean build.
  • GitHub PR 4395: Remove use of temporary files during the ConvertResourcesCases task. This reduced the time for the task from about 610 milliseconds to about 510 milliseconds for a moderately large real-world project on initial clean builds as well as on incremental builds with Android resource changes.
  • GitHub 4415: Starting in Xamarin.Android 10.2.100.7, System.NotSupportedException: Cannot create instance of type ... no Java peer type found caused certain apps to crash during launch after incremental deployments.
  • Java.Interop GitHub PR 559: Switch from using Assembly.GetName().Name to using Assembly.FullName combined with string.Substring() in JavaNativeTypeManager.GetPackageName(). This reduced the time for GenerateJavaStubs from about 390 milliseconds to about 360 milliseconds for an initial clean build of a small Xamarin.Forms test app.
  • Java.Interop GitHub PR 577: Change a LINQ expression to a loop in Java.Interop's IsSubclassOf() extension method. This reduced the time for GenerateJavaStubs from about 560 milliseconds to about 540 milliseconds for an initial clean build of a small Xamarin.Forms test app.
  • Java.Interop GitHub PR 596: Use File.Exists() instead of DirectoryGetFile() in a few places. This reduced the time for the LinkAssembliesNoShrink task from about 710 milliseconds to about 430 milliseconds for a small test Xamarin.Forms app on an initial clean build.

App startup performance

  • GitHub PR 3958: Skip scanning for .exe files during app startup because Xamarin.Android apps only expect .dll assemblies. This reduced the Runtime.init() phase of application startup for a small test app from about 165 milliseconds to about 164 milliseconds on a Google Pixel 3 XL device and from about 530 milliseconds to about 450 milliseconds on an x86 emulator using HAXM.
  • GitHub PR 3992: Optimize the storage format of the per-application Java-to-managed and managed-to-Java type mappings to allow more efficient lookups. This reduced the time to display the first screen of a small test Xamarin.Forms app from about 800 milliseconds to about 790 milliseconds for a Release configuration build on a Google Pixel 3 XL device.
  • GitHub PR 4302: Avoid unneeded calls to GetCustomAttribute() during app startup for the common case where an app has no types decorated with JniAddNativeMethodRegistrationAttribute. Additionally, instead of using a managed method to propagate uncaught exceptions from Java, use a Java method that calls into the unmanaged Xamarin.Android runtime. These changes reduced the time to display the first screen of a small test Xamarin.Forms app from about 730 milliseconds to about 700 milliseconds for a Release configuration build on a Google Pixel 3 XL device.
  • Java.Interop GitHub PR 541 Add [MethodImpl (MethodImplOptions.AggressiveInlining)] to Java.Interop methods and properties that are called many times during Xamarin.Forms app startup. This reduced the time to display the first screen of a blank Xamarin.Forms app from about 560 milliseconds to about 540 milliseconds for a Release configuration build on a Google Pixel 3 XL device.
  • Java.Interop GitHub PR 555: Implement and switch to a new JniTypeManager.GetTypeSignature() method that returns a JniTypeSignature instance instead of an IEnumerable<JniTypeSignature>. This reduced the time to display the first screen of a small test Xamarin.Forms app from about 760 milliseconds to about 750 milliseconds for a Release configuration build on a Google Pixel 3 XL device. It also reduced the number of object allocations from about 9300 to about 8900.
  • Java.Interop GitHub PR 557: Remove unneeded calls to IntrospectionExtensions.GetTypeInfo() now that Java.Interop is a .NET Standard library rather than a PCL. This reduced the time to display the first screen of a small test Xamarin.Forms app from about 755 milliseconds to about 753 milliseconds for a Release configuration build on a Google Pixel 3 XL device.
  • Java.Interop GitHub PR 574: Skip calling GetCustomAttribute() in cases where JniTypeManager.GetSimpleReference() can be used instead.
  • Java.Interop GitHub PR 582: Remove a static array initialization from JniRuntime and an array iteration during JniRuntime.JniTypeManager.GetTypeSignature(), and leverage Type.GetTypeCode() for faster lookups of builtin types.
  • Mono GitHub PR 19102: Use GArray instead of GList when getting custom attributes from an image. This reduces the number of memory allocations during app startup for a standard Xamarin.Forms app, which should improve startup times by several milliseconds.

Android resource editing performance

  • GitHub PR 3674: Correct the Inputs for the _ManagedUpdateAndroidResgen target so that the target is skipped as expected during incremental design-time builds.

Mono Framework version update to 6.12

Xamarin.Android now uses the Mono 6.12 runtime and class libraries at Commit 165f4b03, bringing in about 900 new commits.

Preview bindings for Android 11 Developer Preview 2

This version includes preview bindings for the second Developer Preview of Android 11 from Google. See the Android 11 Developer Preview documentation for additional information about the behavior and API changes in this new Android version. To try the bindings for the new APIs in a Xamarin.Android project, set Compile using Android version: (Target Framework) to Android 10.0.99 (R) under the Application tab of the Visual Studio project property pages. This sets the TargetFrameworkVersion property to v10.0.99 in the .csproj file:

<TargetFrameworkVersion>v10.0.99</TargetFrameworkVersion>

New features

These bindings take advantage of C# 8.0's support for default and static interface members to provide C# interface APIs that more closely match the original Android APIs.

For example, in the Android.Views.TextClassifiers namespace, TextClassifier.HintTextIsEditable is now available as ITextClassifier.HintTextIsEditable, and the old TextClassifier.HintTextIsEditable field is marked [Obsolete].

Note

An older set of bindings for interface constants were also available in Consts classes like TextClassifierConsts in earlier target framework versions. Those classes were marked [Obsolete] for several years. They have been removed completely for the Android 10.0.99 (R) target framework version. Project authors are encouraged to switch to the new interface members like ITextClassifier.HintTextIsEditable at their earliest convenience.

R8 configured to suppress common build errors

Xamarin.Android now configures R8 to skip emitting errors for Java dependency warnings such as:

R8 : warning : Missing class: org.apache.http.client.methods.HttpEntityEnclosingRequestBase
R8 : warning : Missing class: java.lang.ClassValue
R8 : error : Compilation can't be completed because some library classes are missing.

This allows a more gradual transition to R8, particularly for projects that are using R8 for multidex only and not code shrinking.

Although these R8 warnings will no longer cause the build to fail, project authors are encouraged to address the warnings at their earliest convenience and then set R8 back to its original stricter behavior. To restore the original behavior, set the AndroidR8IgnoreWarnings MSBuild property to false in the .csproj file:

<PropertyGroup>
  <AndroidR8IgnoreWarnings>false</AndroidR8IgnoreWarnings>
</PropertyGroup>

Example: How to solve Missing class: org.apache.http.client

R8 : warning : Missing class: org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Best solution

Update any NuGet packages or Java dependencies that use the Apache HTTP client to newer versions that use java.net.HttpURLConnection instead. This is the best solution because starting in Android 6.0 Marshmallow (API level 23), the Apache HTTP client is deprecated in favor of the more efficient HttpURLConnection.

Second-best solution

If new library versions are not yet available that use HttpURLConnection, then, where possible, update any NuGet packages that use Apache HTTP client to newer versions that include a UsesLibraryAttribute for org.apache.http.legacy:

[assembly: UsesLibrary("org.apache.http.legacy", false)]

NuGet package authors who cannot yet update all Java dependencies to use HttpURLConnection are encouraged to add this attribute to their projects as soon as possible.

This attribute automatically generates the following element under the <application> node of AndroidManifest.xml for any app that references the NuGet package:

<uses-library android:name="org.apache.http.legacy" android:required="false" />
Fallback solution

If updated NuGet package versions are not yet available with the attribute, then add the same UsesLibraryAttribute directly to the application project instead:

[assembly: UsesLibrary("org.apache.http.legacy", false)]
Background information

The Missing class: org.apache.http.client warning indicates that the app has a Java dependency on the Apache HTTP client. Starting in Android 6.0 Marshmallow (API level 23), that client was deprecated and moved out of android.jar into its own org.apache.http.legacy.jar library. As a result, applications that use Apache HTTP client on Android 6.0 or higher will only be able to call the APIs successfully if they declare the use of org.apache.http.legacy via a <uses-library> element in AndroidManifest.xml. Otherwise, the API calls will fail with exceptions similar to:

Java.Lang.NoClassDefFoundError: Failed resolution of: Lorg/apache/http/impl/client/DefaultHttpClient

Example: How to solve Missing class: java.lang.ClassValue

R8 : warning : Missing class: java.lang.ClassValue
Solution

It is typically safe to suppress this warning:

  1. Add a new text file to the project, named for example proguard-rules.pro.

  2. Set the contents of the file to:

    -dontwarn java.lang.ClassValue

  3. Edit the .csproj file in a text editor and add --pg-conf proguard-rules.pro to the AndroidR8ExtraArguments MSBuild property, for example by adding the following lines:

    <PropertyGroup>
  <AndroidR8ExtraArguments>--pg-conf proguard-rules.pro</AndroidR8ExtraArguments>
</PropertyGroup>

    (If the project is configured to use R8 for code shrinking, an easier option is to set the Build Action of proguard-rules.pro to ProguardConfiguration in the Visual Studio Properties window, but that approach is not yet supported when using R8 for multidex only.)

Background information

The Missing class: java.lang.ClassValue warning indicates that the app references a library that uses java.lang.ClassValue. Typically this happens when the app references a library that was built to run on multiple Java platforms. On Android, the java.lang.ClassValue type does not exist in the java.lang package.

One known scenario that produces this warning is when an app references the Xamarin.Firebase.Firestore NuGet package, which depends on the cross-platform Google Guava library. Guava uses java.lang.ClassValue, but it only uses it on platforms where it is available, so it is safe to suppress the Missing class: java.lang.ClassValue warning for that library.

A future version of the Xamarin.Guava.Google NuGet package will provide the -dontwarn java.lang.ClassValue R8 rule to suppress the warning automatically. In the mean time, application authors can suppress the warning by adding the rule to their app projects directly.

More thorough clean of obj directory between builds

In previous versions, Xamarin.Android reserved a costlier, more complete incremental clean of the intermediate output directory for special scenarios where a NuGet package changed or where the AndroidPackageNamingPolicy MSBuild property changed. Xamarin.Android 10.3 expands this behavior to perform the more complete clean for changes to several other MSBuild properties:

  • AndroidAotMode
  • AndroidCreatePackagePerAbi
  • AndroidDexTool
  • AndroidEmbedProfilers
  • AndroidEnableProfiledAot
  • AndroidExplicitCrunch
  • AndroidGenerateJniMarshalMethods
  • AndroidIncludeDebugSymbols
  • AndroidLinkMode
  • AndroidLinkSkip
  • AndroidLinkTool
  • AndroidNdkDirectory
  • AndroidPackageFormat
  • AndroidSdkBuildToolsVersion
  • AndroidSdkDirectory
  • AndroidSequencePointsMode
  • AndroidUseLatestPlatformSdk
  • AndroidUseSharedRuntime
  • AotAssemblies
  • BundleAssemblies
  • EmbedAssembliesIntoApk
  • JavaSdkDirectory
  • MonoSymbolArchive
  • OS
  • TargetFrameworkVersion
  • XamarinAndroidVersion

This should reduce the number of cases where project authors need to run a full clean by hand after changing one of these properties, such as after updating to a new Xamarin.Android version.

Changes to these particular properties already triggered additional build steps, so this new behavior should not noticeably increase incremental build times. As in the past, to get the best incremental build times, avoid changing these properties back and forth too much between builds.

Compatibility with embedded debug information

The Mono Framework version in this Xamarin.Android version adds compatibility for reading embedded debugging information from assemblies built with Build > Advanced > Debugging information set to Embedded in the Visual Studio project property pages. This corresponds to the embedded value for the DebugType MSBuild property in the .csproj file:

<PropertyGroup>
  <DebugType>embedded</DebugType>
</PropertyGroup>

See the symbol embedding design documentation for more information.

Support for Android App Bundle configuration files

The Android App Bundle publishing format includes an option to customize certain details about how APKs are generated from the bundle, such as whether or not a separate configuration APK is generated for each set of language resources, screen density resources, and ABI libraries. See the documentation about BundleConfig.json files to learn more. Xamarin.Android now includes an option to pass this kind of configuration file to bundletool during the build process.

To specify a configuration file, set the AndroidBundleConfigurationFile MSBuild property to the path of the file. For example, add lines similar to the following to the .csproj file:

<PropertyGroup>
  <AndroidBundleConfigurationFile>BundleConfig.json</AndroidBundleConfigurationFile>
</PropertyGroup>

Note

Xamarin.Android configures some of the settings automatically, including the list of file extensions to leave uncompressed.

Stream.Seek() for file streams from Android APIs

Until now, Stream.Seek() and related properties like Stream.Position always threw NotSupportedException on Stream instances returned from Android API methods. In Xamarin.Android 10.3, Stream.Seek() and the other related properties are now available on these Stream instances when the underlying Java types inherit from FileInputStream.

Localized errors and warnings for builds

Many of the errors and warnings in the Xamarin.Android build tasks now provide localized messages that match the region and language settings of the build environment.

Java.Interop nullable reference types compatibility

The Java.Interop assembly has been updated for compatibility with C# 8.0 nullable reference type checks. Any projects that are using types directly from the Java.Interop assembly can now optionally place that code in a nullable context to take advantage of additional compiler nullability checks. Most Xamarin.Android projects only use the Java.Interop assembly indirectly, so this change is not relevant for most projects.

Mono.Data.Sqlite SQLite version update

The version of SQLite used by Mono.Data.Sqlite in Xamarin.Android has been updated from 3.28.0 to 3.31.1, bringing in security fixes, improvements, and bug fixes.

Default Android tools versions update to 29.0

The default Android SDK Build-Tools version has been updated from 28.0.3 to 29.0.2. This version can be changed per-project if needed via the AndroidSdkBuildToolsVersion MSBuild property.

The default Android SDK Platform-Tools version has been updated from 28.0.0 to 29.0.5. This version can be changed per-project if needed via the AndroidSdkPlatformToolsVersion MSBuild property.

XA1011 error for D8 with ProGuard

Any project using the D8 DEX compiler that has either Code shrinker (AndroidLinkTool) set to ProGuard or the older AndroidEnableProguard MSBuild property set to true will now get an XA1011 build error:

error XA1011: Using ProGuard with the D8 DEX compiler is no longer supported. Please update `$(AndroidLinkTool)` to `r8`.

In the past, this configuration was allowed, but now only the R8 code shrinker is supported for use with the D8 DEX compiler.

To resolve this error, update the Code shrinker setting in the Visual Studio project property pages to r8. This corresponds to the r8 value for the AndroidLinkTool MSBuild property in the .csproj file:

<PropertyGroup>
  <AndroidLinkTool>r8</AndroidLinkTool>
</PropertyGroup>

Note

R8 might in some cases produce new build warnings or errors compared to ProGuard, so the ProGuard rules for the project might require updates after this change.

XA0122 and CS0618 warnings for deprecated Java.Interop.DoNotPackageAttribute

Any app project that references a Xamarin.Android bindings library containing uses of Java.Interop.DoNotPackageAttribute will now get a XA0122 build warning:

warning XA0122: Assembly 'Library1' is using a deprecated attribute '[assembly: Java.Interop.DoNotPackageAttribute]'. Use a newer version of this NuGet package or notify the library author.

Similarly, any library project that includes a use of [assembly: Java.Interop.DoNotPackageAttribute] will now get a CS0618 build warning:

warning CS0618: 'DoNotPackageAttribute' is obsolete: 'This attribute is deprecated and will be removed in a future release. Use the @(AndroidExternalJavaLibrary) MSBuild item group instead.'

Java.Interop.DoNotPackageAttribute will be removed in a future release. NuGet package authors are encouraged to transition away from it at their earliest convenience. The recommended approach is to include the external library as a separate file within the NuGet package and add a .props file in both the build and buildTransitive directories of the NuGet package that sets the library as a AndroidExternalJavaLibrary item for consuming app projects. For example, if the external library is included alongside the .props file in the build and buildTransitive directories, then the contents of the .props file can be:

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <ItemGroup>
    <AndroidExternalJavaLibrary Include="$(MSBuildThisFileDirectory)*.jar">
  </ItemGroup>
</Project>

CS0619 error for obsolete constant fields

Certain previously deprecated constant fields in the Android API bindings have been updated from [Obsolete] to [Obsolete(error:true)]. These types will now produce CS0619 errors instead of CS0618 warnings.

To resolve these errors, switch to the types mentioned in the error messages. For example, for Android.Content.ComponentCallbacks2.TrimMemoryBackground, the error message is:

error CS0619: 'ComponentCallbacks2.TrimMemoryBackground' is obsolete: 'This constant will be removed in the future version. Use Android.Content.TrimMemory enum directly instead of this field.'

To resolve this example error, switch the type to Android.Content.TrimMemory.Background.

Bindings projects exclusion of private nested types

Previously, Xamarin.Android bindings projects generated public bindings for all nested Java types, even when the types had private or package-private visibility. Bindings projects now respect private visibilities on nested types and no longer generate bindings for those types.

Note

This change in behavior can result in new C# compiler errors for bindings projects, such as:

error CS0426: The type name 'AttribOp' does not exist in the type 'CSSParser'
error CS0115: 'MapControllerOld.HalfCosinusalDeceleratingAnimationRunner.JniPeerMembers': no suitable method found to override

To restore any needed missing types, adjust the visibilities by adding rules similar the following to the Transforms\Metadata.xml file:

<attr path="/api/package[@name='com.caverock.androidsvg']/class[@name='CSSParser.AttribOp']" name="visibility">public</attr>
<attr path="/api/package[@name='org.osmdroid.views']/class[@name='MapControllerOld.CosinusalBasedAnimationRunner']" name="visibility">public</attr>

Removal of AndroidExplicitCrunch feature

In previous Xamarin.Android versions, setting the AndroidExplicitCrunch MSBuild property to true would configure the build to crunch PNG drawable resources using a separate MSBuild task before passing them to AAPT.

This feature was never compatible with projects configured to use AAPT2 and was automatically disabled in those projects. For projects configured to use the older AAPT tool, this feature could cause builds to rerun AAPT on every build. Due to these limitations, this feature has now been removed from Xamarin.Android. The AndroidExplicitCrunch MSBuild property is now ignored. Project authors who added this property to their .csproj files in the past can now remove it.

Removal of F# Resource.designer.fs file support

F# Xamarin.Android projects now generate Resource.designer.cs files instead of Resource.designer.fs files. The recommended way to consume these files is to the install the Xamarin.Android.FSharp.ResourceProvider NuGet package, which surfaces F# types for the content in the .cs file.

See the DisplayPlatformInfo sample for an example of how to use Xamarin.Android.FSharp.ResourceProvider.

Note

Xamarin.Android.FSharp.ResourceProvider does not support Resource.designer.cs files located in the intermediate output directory, so generation of resource designer files in the intermediate output directory is now disabled for F# projects.

Removal of keystore certificate fingerprint from build output

The performance improvement from GitHub PR 4308 that skips executing keytool -list during the build means that the SHA-1 certificate fingerprint no longer appears in the build output. To determine certificate fingerprints in this version, follow the steps from the Finding your Keystore's Signature guide instead.

Removal of .exe reference support

To improve performance, Xamarin.Android no longer probes for .exe files during app startup.

Projects must now use .dll assemblies for all dependencies. Compatible dependency types include .NET Standard libraries, Xamarin.Android class libraries, Xamarin.Android binding libraries, shared projects, and portable class libraries.

Background information

The Xamarin.Android build process has historically used .dll files by default, so this change should only affect dependencies built using other project types or custom build targets.

Also, the build process has intentionally skipped .exe files when packaging APKs since as far back as Xamarin.Android 9.4, so this new Xamarin.Android 10.3 behavior at run time is unlikely to affect app behavior for project authors upgrading from Xamarin.Android 9.4 or above.

Issues fixed in Xamarin.Android 10.3.1.0

Application and library build and deployment

  • Developer Community 861086: Starting in Xamarin.Android 10.1, errors similar to 'fixedsize' is incompatible with attribute ChildLayout (attr) enum prevented building projects successfully if they contained custom attribute names ending with the word Layout.
  • Developer Community 888836: ADB1000: Deployment failed System.ArgumentOutOfRangeException ... Parameter name: length could prevent successful deployment on certain devices.
  • Developer Community 917114: error MSB4018: The "CreateManagedLibraryResourceArchive" task failed unexpectedly ... System.ArgumentOutOfRangeException: startIndex cannot be larger than length of string. caused builds to abort for Xamarin.Android class library projects that included AndroidAsset items with paths outside of the project directory.
  • GitHub 2654: Directory obj\Release\android\assets contains *.dll but no debug symbols file was found. warnings were shown by default in Release configuration builds for apps that referenced libraries without debug symbols. These warnings were often caused by NuGet packages and so could not be resolved by app project authors. These warnings have been demoted to informational messages for now.
  • GitHub 3636: Error inflating class android.support.v7.widget.FitWindowsLinearLayout ---> Java.Lang.ClassNotFoundException: Didn't find class "android.support.v7.widget.FitWindowsLinearLayout" and similar errors could prevent apps built with Code shrinker set to ProGuard or r8 from running successfully unless custom ProGuard rules were added to the project by hand. In Xamarin.Android 10.3, projects configured to use AAPT2 now pass the --proguard option to AAPT2 to generate default ProGuard rules that more closely match the defaults for Android Studio projects, removing the need to add custom rules for common scenarios like the FitWindowsLinearLayout type from the Android Support Library.
  • GitHub 3813: Xamarin.Android did not yet support Android App Bundle configuration files.
  • GitHub PR 4149: The managed linker did not yet consider the Java.Interop.GenericMarshaler namespace for linking when set to link SDK assemblies only.
  • GitHub PR 4214: The ConvertResourcesCases task could leave behind a file in the user's temporary directory after the build.
  • GitHub PR 4340: error XA0031: Java SDK 1.8 or above is required when targeting FrameworkVersion did not yet mention the full MSBuild property name TargetFrameworkVersion.
  • GitHub PR 4357: error XA0003 and error XA0004 messages did not yet mention AndroidManifest.xml or include the full name of the android:versionCode XML attribute.
  • GitHub PR 4378: Misleading error MSB6006: "jarsigner.exe" exited with code 1 or error MSB6006: "java.exe" exited with code 2 was shown if the AndroidKeyStore MSBuild property was true and the AndroidSigningKeyStore property was set to a file that did not exist.
  • GitHub PR 4387: error XA1010: Invalid application placeholders... did not yet mention the associated AndroidManifestPlaceholders MSBuild property or list the current value of the property.
  • GitHub 4409: ; expected prevented using comma-delimited lists in Aliases MSBuild item metadata on Xamarin.Android library project references.
  • GitHub PR 4422: error APT0001: unknown option... was inaccurate for cases where an option was misspelled, and it did not yet mention the relevant MSBuild properties.
  • GitHub PR 4444: System.IO.IOException: The directory is not empty could sometimes prevent the RemoveDirFixed task from removing temporary build directories. The task now produces a warning instead, allowing the build to complete successfully.
  • GitHub 4478, GitHub 4486: On macOS, starting in Xamarin.Android 10.2, [INSTALL_FAILED_INVALID_APK: ... base.apk code is missing] and Module 'base' has no dex files prevented deploying successfully for certain projects configured to use the DX DEX compiler.

Application behavior on device and emulator

  • GitHub 4110: Unable to get provider mono.MonoRuntimeProvider_1: java.lang.ClassNotFoundException prevented apps containing broadcast receivers from launching successfully if they were built with ProGuard or R8 enabled.

Application Mono Framework behavior on device and emulator

Design-time build

  • GitHub 2413: The _ManagedUpdateAndroidResgen target was running during every incremental design-time build.

Bindings projects

  • GitHub PR 4385: You have Jar libraries, lint.jar, lint.jar, ... that have the identical name with inconsistent file contents could prevent apps from using custom bindings libraries for certain Java libraries. This was discovered while preparing new versions of the Xamarin.AndroidX bindings libraries.
  • Java.Interop GitHub 519: error CS1001: Identifier expected prevented building binding projects for Java libraries that defined classes outside of a Java package.
  • Java.Interop GitHub 565: error CS0103: The name 'p0' does not exist in the current context prevented building bindings projects for Java libraries that contained explicit interface property implementations.
  • Java.Interop GitHub 571: Kotlin: Hiding internal ... method caused missing bindings for public Kotlin methods in cases where the method names were the same as the names of private properties or fields.
  • Java.Interop GitHub 572: Package-private nested types were not automatically excluded from bindings, resulting in errors similar to error: ... is not public in ...; cannot be accessed from outside package when attempting to use the bindings.

Thank you

A big Thank You! to community members who contributed improvements in this release:

Feedback welcome

Your feedback is important to us. If there are any problems with this release, check our GitHub Issues, Xamarin.Android Community Forums and Visual Studio Developer Community for existing issues. For new issues within the Xamarin.Android SDK, please report a GitHub Issue. For general Xamarin.Android experience issues, let us know via the Report a Problem option found in your favorite IDE under Help > Report a Problem.

Open source

Xamarin.Android 10.3 is based on the open-source Xamarin.Android repositories: