Xamarin.Android provides open-source bindings of the Android SDK for use with .NET managed languages such as C#
C# C Other
Latest commit 2a5fb47 Jan 20, 2017 @jonpryor jonpryor committed with dellis1972 [Xamarin.Android.Build.Tasks] _CreateNativeLibraryArchive needs refer…
…ences (#393)

Context: 7343965
Context: 743529c
Context: https://gitter.im/Microsoft/msbuild?at=58823bfd074f7be763f6aeaf

We want to be able to build the xamarin-android repo via `msbuild`,
because `msbuild` may be the default build system in the "Cycle 10"
timeframe (please oh please oh please...) and because building with
`msbuild` is a prerequisite to sanely building on Windows, which would
be extremely handy for increasing our contributor base.

Unfortunately, [commit 743529c didn't fix all problems][0]:

	error MSB4018: The "CreateNativeLibraryArchive" task failed unexpectedly.
	error MSB4018: System.IO.FileNotFoundException: ../sqlite-xamarin/src/main/libs/armeabi-v7a/libsqlite3_xamarin.so does not exist

The MSB4018 is a *symptom*, not a cause. The *cause* of the error is

1. `Mono.Data.Sqlite.csproj` depends on build artifacts from building
    the `sqlite-xamarin.mdproj` project.
2. `sqlite-xamarin.mdproj` isn't being built before

(2) is a bit of a head scratcher: `Mono.Data.Sqlite.csproj` has a
`@(ProjectReference)` including `sqlite-xamarin.mdproj`; surely that's
enough, right?

Wrong. `@(ProjectReference)` isn't "special"; it's just an item group,
interpreted by the `ResolveReferences` target.

The problem we're seeing here is that the `ResolveReferences` target
isn't executed before the `_CreateNativeLibraryArchive` target is
executed. Consequently `@(ProjectReference)` isn't handled *at all*
prior to the `_CreateNativeLibraryArchive` invocation, which is why
`sqlite-xamarin.mdproj` isn't built before `Mono.Data.Sqlite.csproj`.

(Why's this work on `xbuild`? No idea!)

Update the `_CreateNativeLibraryArchive` target to add a
`DependsOnTargets` value of `ResolveReferences`. This explicit target
references ensures that referenced projects (`sqlite-xamarin.mdproj`)
are resolved and built before the current project
(`Mono.Data.Sqlite.csproj`), allowing cross-references of build
artifacts in a sane(r) fashion.

[0]: https://jenkins.mono-project.com/view/Xamarin.Android/job/xamarin-android-msbuild/99/consoleText
Failed to load latest commit information.
Documentation [docs] Fix links in DevelopmentTips.md. Nov 30, 2016
build-tools [build] Support building *from clean* with `msbuild` (Take 2!) (#391) Jan 20, 2017
external [monodroid] Create AppDomain instances for designer context (#359) Jan 17, 2017
samples/HelloWorld [tests] Import tests/locale from monodroid/2ed1f0f6 (#316) Nov 24, 2016
src [Xamarin.Android.Build.Tasks] _CreateNativeLibraryArchive needs refer… Jan 20, 2017
tests [Xamarin.Android.Build.Tasks] Default $(AndroidClassParser) is jar2xml ( Jan 9, 2017
tools [tools/scripts] Add mono-symbolicate to the build system. (#335) Dec 15, 2016
.gitattributes Fix line endings Jul 6, 2016
.gitignore [tests] Run .apk unit tests and collect TestResults.xml (#305) Nov 21, 2016
.gitmodules use mono/linker sources to build the linker (#291) Nov 11, 2016
Configuration.Java.Interop.Override.props [build] Fix Java.Interop utilities directory Jun 9, 2016
Configuration.Override.props.in [Xamarin.Android.Build.Tasks] Support new manifest attributes for API… Aug 1, 2016
Configuration.props [build] Support building *from clean* with `msbuild` (Take 2!) (#391) Jan 20, 2017
Dockerfile Add Dockerfile. (#204) Sep 2, 2016
LICENSE [LICENSE] Add the libzip license. (#112) Jul 8, 2016
Makefile [build] Support building *from clean* with `msbuild` (#355) Jan 10, 2017
README.md [README] Add Xamarin.Android Cycle 9 download links Dec 8, 2016
Xamarin.Android-Tests.sln [tests] Import tests/codegen from monodroid/5fc80f27 Dec 1, 2016
Xamarin.Android.sln [remap-assembly-ref] Properly add to the XA solution (#351) Jan 5, 2017
product.snk [Mono.Android, Mono.Android.Export] Sign assemblies. (#29) May 10, 2016



Xamarin.Android provides open-source bindings of the Android SDK for use with .NET managed languages such as C#.


Build Status

Platform Status
OSS macOS OSS macOS x86_64
OSS Ubuntu OSS Linux/Ubuntu x86_64


Platform Status
Commercial Xamarin.Android 7.0 (Cycle 8) for macOS Commercial Xamarin.Android 7.0, macOS
Commercial Xamarin.Android 7.1 (Cycle 9) for macOS Commercial Xamarin.Android 7.1, macOS
Commercial Xamarin.Android 7.1.99 (master) for macOS Commercial Xamarin.Android 7.1.99, macOS


The Xamarin.Android build is heavily dependent on MSBuild, with the intention that it should (eventually?) be possible to build the project simply by checking out the repo, loading Xamarin.Android.sln into an IDE, and Building the solution. (This isn't currently possible, and may never be, but it's the vision.)

However, some properties may need to be altered in order to suit your requirements, such as the location of a cache directory to store the Android SDK and NDK.

To modify the build process, copy Configuration.Override.props.in to Configuration.Override.props, and edit the file as appropriate. Configuration.Override.props is <Import/>ed by Configuration.props and will override any default values specified in Configuration.props.

Overridable MSBuild properties include:

  • $(AndroidApiLevel): The Android API level to bind in src/Mono.Android. This is an integer value, e.g. 15 for API-15 (Android 4.0.3).
  • $(AndroidFrameworkVersion): The Xamarin.Android $(TargetFrameworkVersion) version which corresponds to $(AndroidApiLevel). This is usually the Android version number with a leading v, e.g. v4.0.3 for API-15.
  • $(AndroidSupportedHostJitAbis): The Android ABIs for which to build a host JIT and Xamarin.Android base class libraries (mscorlib.dll/etc.). The "host JIT" is used e.g. with the Xamarin Studio Designer, to render Xamarin.Android apps on the developer's machine. There can also be support for cross-compiling mono for a different host, e.g. to build Windows libmonosgen-2.0.dll from OS X. Supported host values include:

    • Darwin
    • Linux
    • mxe-Win64: Cross-compile Windows 64-bit binaries from Unix.

    The default value is $(HostOS), where $(HostOS) is based on probing various environment variables and filesystem locations. On OS X, the default would be Darwin.

  • $(AndroidSupportedTargetJitAbis): The Android ABIs for which to build the the Mono JIT for inclusion within apps. This is a :-separated list of ABIs to build. Supported values are:

    • armeabi
    • armeabi-v7a
    • arm64-v8a
    • x86
    • x86_64
  • $(AndroidToolchainCacheDirectory): The directory to cache the downloaded Android NDK and SDK files. This value defaults to $(HOME)\android-archives.
  • $(AndroidToolchainDirectory): The directory to install the downloaded Android NDK and SDK files. This value defaults to $(HOME)\android-toolchain.
  • $(HostCc), $(HostCxx): The C and C++ compilers to use to generate host-native binaries.
  • $(JavaInteropSourceDirectory): The Java.Interop source directory to build and reference projects from. By default, this is external/Java.Interop directory, maintained by git submodule update.
  • $(MakeConcurrency): make(1) parameters to use intended to influence the number of CPU cores used when make(1) executes. By default this uses -jCOUNT, where COUNT is obtained from sysctl hw.ncpu.
  • $(MonoSgenBridgeVersion): The Mono SGEN Bridge version to support. Valid values include:

    • 4: Mono 4.6 support.
    • 5: Mono 4.8 support. This is the default.

Build Requirements

Building Xamarin.Android requires:

Mono MDK

Mono 4.4 or later is required to build on OS X and Linux.

(This is because the build system uses the XmlPeek task, which was first added in Mono 4.4.)

Java Development Kit

The Java Development Kit may be downloaded from the Oracle Java SE Downloads page.


Autotools -- including autoconf and automake -- are required to build the Mono runtimes.

On OS X, autotools are distributed with Mono.framework.

If you run into issues regarding autoconf or automake try to install it with brew via:

brew install automake


The xxd utility is used to build src/monodroid. It is installed by default on OS X. Linux users may need to separately install it; it may be part of the vim-common package.

Android NDK, SDK

To simplify building Xamarin.Android, important pieces of the Android SDK and Android NDK will be automatically downloaded and installed from Google's website. Downloaded files are cached locally, by default into $(AndroidToolchainCacheDirectory). The Android NDK and SDK will be installed by default into $(AndroidToolchainDirectory).

The files that will be downloaded and installed are controlled by build-tools/android-toolchain/android-toolchain.projitems via the @(AndroidNdkItem) and @(AndroidSdkItem) item groups, and the URL to download files from is controlled by the $(AndroidUri) property.


At this point in time, building Xamarin.Android is only supported on OS X. We will work to improve this.

To build Xamarin.Android, first prepare the project:

make prepare

This will perform git submodule update, and any other pre-build tasks that need to be performed. After this process is completed, ensure there is no existing git changes in the external folder.

On the main repo, you can use git status to ensure a clean slate.

Then, you may do one of the following:

  1. Run make:

  2. Load Xamarin.Android.sln into Xamarin Studio and Build the project.

    Note: The Mono.Android project may fail on the first build because it generates sources, and those sources won't exist on the initial project load. Rebuild the project should this happen.

Linux build notes

If you have the binfmt_misc module enabled with any of Mono or Wine installed and you plan to cross-build the Windows compilers and tools (by enabling the mxe-Win32 or mxe-Win64 host targets) as well as LLVM+AOT targets, you will need to disable binfmt_misc for the duration of the build or the Mono/LLVM configure scripts will fail to detect they are cross-compiling and they will produce Windows PE executables for tools required by the build.

To disable binfmt_misc you need to issue the following command as root:

    echo 0 > /proc/sys/fs/binfmt_misc/status

and to enable it again, issue the following command:

    echo 1 > /proc/sys/fs/binfmt_misc/status

macOS Build Notes

The android-toolchain.projitems, libzip.projitems, and monodroid.projitems project files, among others, use the @(RequiredProgram) build action to check for the existence of a program within $PATH during the build. If a required program doesn't exist, then the build will fail and a suggested brew install command line will be provided to install the missing commands.

Brew Programs

Suggested brew install commands:

brew install cmake
brew install libtool
brew install p7zip
brew install gdk-pixbuf
brew install gettext
brew install coreutils
brew install findutils
brew install gnu-tar
brew install gnu-sed
brew install gawk
brew install gnutls
brew install gnu-indent
brew install gnu-getopt
brew install intltool
brew install scons
brew install wget
brew install xz

If any program is still not found, try to ensure it's linked via:

brew link <package name>

Build Output Directory Structure

There are two configurations, Debug and Release, controlled by the $(Configuration) MSBuild property.

The bin\Build$(Configuration) directory, e.g. bin\BuildDebug, contains artifacts needed for building the repository. They should not be needed for later execution.

The bin\$(Configuration) directory, e.g. bin\Debug, contains redistributable artifacts, such as tooling and runtimes. This directory acts as a local installation prefix, in which the directory structure mirrors that of the OS X Xamarin.Android.framework directory structure:

  • bin\$(Configuration)\lib\xbuild\Xamarin\Android: MSBuild-related support files and required runtimes used by the MSBuild tooling.
  • bin\$(Configuration)\lib\xbuild-frameworks\MonoAndroid: Xamarin.Android profiles.
  • bin\$(Configuration)\lib\xbuild-frameworks\MonoAndroid\v1.0: Xamarin.Android Base Class Library assemblies such as mscorlib.dll.
  • bin\$(Configuration)\lib\xbuild-frameworks\MonoAndroid\*: Contains Mono.Android.dll for a given Xamarin.Android $(TargetFrameworkVersion).

Xamarin.Android $(TargetFrameworkVersion)s

Xamarin.Android uses the MSBuild $(TargetFrameworkVersion) mechanism to provide a separate Mono.Android.dll binding assembly for each API level.

This means there is no single Mono.Android.dll, there is instead a set of them.

This complicates the "mental model" for the Mono.Android project, as a project can have only one output, not many (...within reason...). As such, building the Mono.Android project will only generate a single Mono.Android.dll.

To control which API level is bound, set the $(AndroidApiLevel) and $(AndroidFrameworkVersion) properties. $(AndroidApiLevel) is the Android API level, usually a number, while $(AndroidFrameworkVersion) is the Xamarin.Android $(TargetFrameworkVersion).

The default values will target Android API-24, Android 7.0.

For example, to generate Mono.Android.dll for API-19 (Android 4.4):

cd src/Mono.Android
xbuild /p:AndroidApiLevel=19 /p:AndroidFrameworkVersion=v4.4
# creates bin\Debug\lib\xbuild-frameworks\MonoAndroid\v4.4\Mono.Android.dll


The HelloWorld sample may be built with the xabuild script:

$ tools/scripts/xabuild /t:SignAndroidPackage samples/HelloWorld/HelloWorld.csproj

xabuild /t:SignAndroidPackage will generate an .apk file, which may be installed onto an Android device with the adb install command:

$ adb install samples/HelloWorld/bin/Debug/com.xamarin.android.helloworld-Signed.apk

HelloWorld may be launched manually through the Android app launcher, or via adb shell am:

$ adb shell am start com.xamarin.android.helloworld/example.MainActivity


Mailing Lists

To discuss this project, and participate in the design, we use the android-devel@lists.xamarin.com mailing list.

Coding Guidelines

We use Mono's Coding Guidelines.

Reporting Bugs

We use Bugzilla to track issues.

Maintainer FAQ

See DevelopmentTips.md.