Mono For Android 4.0.0


Visual Studio Users: If you're running Mono for Android 1.9.1 or later, you should be prompted to update. Otherwise, download monoandroid-4.0.0.msi and install.

MonoDevelop Users: You should be prompted to upgrade next time you open MonoDevelop, or you can use Help->Check for Updates. IDE support requires MonoDevelop

Major Highlights

Honeycomb and Ice Cream Sandwich support: Honeycomb (Android v3.x) and Ice Cream Sandwich (Android v4.0) are now supported, and APIs introduced in those API levels can now be used from C#.

Google Maps API bindings: We now provide a Mono.Android.GoogleMaps.dll assembly to allow use of the Google Maps API from C#.

Reduced startup performance. The startup overhead for the default template has been reduced by over 50%, as measured on a Nexus One (from 2.451s to 1.141s).

GC Fixes. This release contains additional GC fixes.

Fast Deployment. A new Fast Deployment mode allows for faster development times by cutting down on the time it takes to deploy your application to an emulator or device when no resources or java stubs have changed.

Changes since 1.2.0

Honeycomb and Ice Cream Sandwich Support: We are now providing a Mono.Android.dll for API levels 12 and 14.

We have also ported Honeycomb Gallery sample.

Google Maps API Binding: There is now a managed binding to the Google Maps API that ships with Android. To use this, simply add a reference to the Mono.Android.GoogleMaps.dll assembly. This will automatically add the needed java library reference and the INTERNET permission to your application.

An example project using the Google Maps API is available.

To use the GoogleMaps API, you will need to obtain an API key.

Interface Constant Binding Improvements: The way that constants within Java interfaces is exposed has been overhauled. This should simplify porting Java code which uses interface constants.

Improved string handling: Extension methods are now generated for interface methods which take Java.Lang.ICharSequence and Java.Lang.String. This allows providing System.String-constants when invoking these interface methods.

Java 7 Support: We now correctly build, sign and deploy packages built with Java 7. Note that if you have both installed, we still will use Java 6 as it's more tested by the Android community.

Smaller Application Packages: contains Android Callable Wrappers for many types internal to Mono.Android.dll, and is included in every Mono for Android application package. We have rearchitected how is produced, greatly shrinking its size. The size reductions are also visible in Mono.Android.dll and application packages.

Better Incremental Builds: More of the build system is implemented as MSBuild tasks. This allows us to have better incremental builds, letting us skip pieces that don't need to be rebuilt.


  1.2.0 1.9.0
First Build: 8.66s 8.19s
Code Changes: 5.78s 1.71s
Code Changes Requiring New Java Stubs: 5.78s 2.50s
Resource Changes: 8.18s 6.10s

(Tests are run using the Debug profile of JetBoy.)

Fast Deployment. A new Fast Deployment mode allows for faster development times by cutting down on the time it takes to deploy your application to an emulator or device when no resources or java stubs have changed.

This option is enabled by default and can be toggled via the Mono for Android Build (MD) / Mono for Android Options (VS) options panel. For an optimal use of this mode, your assembly version (on AssemblyInfo.cs) should not be set to automatically change on every build.

  Normal Fast Deployment
Full build and install: 15.6s 15.6s
No changes, build and install: 1.8s 2.5s
Resource change, build and install: 10.8s 10.8s
Code change, build and install: 14.7s 3.9s

(Tests are run using the Debug profile of the Honeycomb Gallery sample, with the Runtime and Platform packages already installed on an emulator running basic api level 14.)

Smarter Linker: Our linker spent the summer at linker community college and came away a bit smarter about what your application really needs in order to run, resulting in a significant release .apk size reduction.

  1.2.0 Size 4.0 Size
Default Template Release .apk 4.21 MB 2.8 MB

Update Notifications for Visual Studio: Visual Studio will now check for Mono for Android updates automatically and notify you if a new release is available:

To turn this off, or to subscribe to beta release notifications, go to Tools->Options->Mono for Android:

System.Numerics: The System.Numerics.dll assembly is now included with Mono for Android, bringing support for System.Numerics.BigInteger and related types.

[UsesPermission] attribute: You can now specify the Android permissions your app requires with an assembly level attribute. This is analogous to adding a <uses-permission> element to the AndroidManifest.xml.

[assembly:UsesPermission (Name = Android.Manifest.Permission.Internet)]

[UsesLibrary] attribute: You can now specify the Android extra libraries your app requires with an assembly level attribute. This is analagous to adding a <uses-library> element to the AndroidManifest.xml.

[assembly:UsesLibrary (Name = "")]

Unhandled Exception Support in VS: When you hit an unhandled exception in your application while debugging, VS will now let you know what the exception is instead of just stopping with a green line.

System.Console messages are copied to the Android Debug Log: Output generated to System.Console.Out and System.Console.Error are now copied to the Android Debug Log.

Java add*Listener() methods are now bound as events. This reduces the number of instances in which Java interfaces need to be implemented for event handling.

Breaking Changes

  • Every method that takes an (IntPtr handle) parameter has been changed to take an(IntPtr handle, JniHandleOwnership transfer) parameter pair. This includes all constructors . - Anyone using JNI and creating wrapper objects will need to update their code, probably by using JniHandleOwnership.DoNotTransfer .
  • Existing (IntPtr) constructors should be changed similar to:
TypeName(IntPtr handle) : base (handle) {}
TypeName(IntPtr handle, JniHandleOwnership transfer) : base(handle, transfer) {}
  • Java.Lang.Object.Dispose() is no longer virtual, and instead the IDisposable pattern is propertly implemented. Developers overriding the Dispose() method should now override the Dispose(bool) method. - Note : It is very important that you update any base.Dispose() calls tobase.Dispose(disposing). Failure to do so will result in a stack overflow. Unfortunately, stack overflows aren't handled very well at present, so it will actually result in your application dying without any stack trace at all.

  • Additional int to enumeration parameter and return type conversions.

  • Java event handling methods which return boolean (e.g. and android.contentDialogInterface.OnKeyListener.onKey() ) are now mapped to events instead of properties, e.g. Android.App.Dialog.KeyPress is now an event, not a property.
  • Enumeration types and members only exist in the API levels for which they actually exist in Java.

API Changes

Bug Fixes

  • 281 : Tie armeabi libmono to a single core. This allows apps that only bundle armeabi (and not armeabi-v7a) to safely run on SMP devices.
  • 619 : LinearLayout.SetGravity( int ) should be GravityFlags.
  • 669 : EditText.ImeOptions should be of type Android.Views.InputMethods.ImeAction.
  • 1048 Fix that stops Visual Studio from crashing from a FormatException.
  • 1052 : Race condition in the VS plugin would cause an exception while deploying.
  • 1114 : Generate array parameters in Android Callable Wrappers.
  • 1115 : DeflateStream doesn't work
  • 1140 : Embed Mono for Android version number into License.rtf.
  • 1148 : EditText.IOnKeyListener.OnKey keyCode parameter should be of Keycode type.
  • 1522 : Fix JNIEnv.GetArray<byte>(IntPtr); improve array marshaling support.
  • 1534 Fix to stop applications from freezing up due to Garbage Collection usage
  • 1703 : Install License.rtf so it can be viewed after installation.
  • 1710 : Embed <since/> information in the extracted documentation. Android type and member documentation at now shows the API level that the type/member was introduced, e.g. in the Requirements section for the Android.App.Dialog docs, it says: Since: API Level 1.
  • 1726 : Add events on Android.Animation.Animator , Android.App.ActionBar.Tab .
  • 1730 : ValueAnimatorRepeatMode.Infinite should not be an enum value
  • 1731 : Preserve the Android.Animation.ValueAnimator.SetEvaluator method in API level 14.
  • 1733 : ActionBar.LayoutParams.Gravity should be of enum type.
  • 1738 : Java events which return boolean are transformed into events with an EventArgssubclass containing a Handled property instead of being a property.
  • 1740 : TextView.SetImeAction() takes an enum.
  • 1773 : More int->enum changes.
  • 1775 : ILocationListener.OnStatusChanged() takes an enum parameter.
  • 1776 : Add Android.OS.Handler(Action<Message>) constructor.
  • 1781 : Fix exception when processing [ContentProvider] attribute.
  • 1787 : int->enum changes.
  • 1804 : Add ItemizedOverlay.CreateItem() method.
  • 1927 : Better expose InputStream.Available() from wrappers. Add Stream.IsDataAvailable() extension method.
  • 2004 : Fix execution of GLCube sample.
  • 660400 : Support jagged array types in method declarations.
  • 691188 : int->enum in Android.Media.SoundPool constructor.
  • Correctly handle projects that do not contain Resources.
  • It should now be possible to target API level 10 (Android v2.3.3).
  • Fixed InvalidCastException that would result from subscribing to AndroidEnvironment.UnhandledExceptionRaiser.
  • Fix End-Of-Stream translation in Android.Runtime.InputStreamAdapter and related types.
  • Attach Mono's finalizer thread to Dalvik
  • Improve merging of [Application] attribute and <application/> AndroidManifest.xml element.
  • msbuild /t:Clean will no longer remove the debug keystore.
  • Android.App.ActivityAttribute-related enumerations have been updated to API level 13.


Warning: Samsung shipped a broken kernel with Android 2.1, which is not able to support JIT compilation. If you possess a Galaxy-class device with Android 2.1, you will get unexpected results, this is caused by a kernel bug that breaks cache coherency, rendering any engine doing JIT compilation useless. Check with your manufacturer/carrier for an Android 2.2 update.

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