[Mono.Android] Add NRT annotations.

Documentation/release-notes/4227.md

@@ -0,0 +1,18 @@
+#### Mono.Android.dll Nullable Reference Type Annotations
+
+`Mono.Android.dll` assemblies of all platform levels are now annotated with 
+C#8's nullable reference types (NRT).  Users who opt their applications into 
+this feature with `<Nullable>enable</Nullable>` will receive warnings if their 
+code does not properly account for possible `null` values.
+
+General documentation for the NRT feature is available here: 
+https://docs.microsoft.com/en-us/dotnet/csharp/nullable-references.
+
+Note:
+The majority of `Mono.Android.dll` is automatically generated from the Android 
+Java source, including these new annotations.  As such, we will not be manually 
+fixing places where the Android source code is not annotated correctly.
+
+If there is an error regarding nullability for any of the Mono.Android APIs 
+that Xamarin adds to the Android source (such as `JavaList` or `InputStreamAdapter`), 
+please file a bug so we can properly annotate our additions.

src/Mono.Android/Android.Accounts/AccountManager.cs

@@ -10,12 +10,12 @@ namespace Android.Accounts {
 
 	public partial class AccountManager {
 
-		public static AccountManager FromContext (Context context)
+		public static AccountManager? FromContext (Context context)
 		{
 			return context.GetSystemService (Context.AccountService) as AccountManager;
 		}
 
-		WeakReference weak_implementor_AccountsUpdated;
+		WeakReference? weak_implementor_AccountsUpdated;
 		public event EventHandler<AccountsUpdateEventArgs> AccountsUpdated {
 			add {
 				AndroidEventHelper.AddEventHandler<IOnAccountsUpdateListener, IOnAccountsUpdateListenerImplementor>(
@@ -33,7 +33,7 @@ public event EventHandler<AccountsUpdateEventArgs> AccountsUpdated {
 			}
 		}
 
-		void SetOnAccountsUpdatedListener (IOnAccountsUpdateListener value)
+		void SetOnAccountsUpdatedListener (IOnAccountsUpdateListener? value)
 		{
 			AddOnAccountsUpdatedListener (value, null, false);
 		}

src/Mono.Android/Android.Animation/Animator.cs

@@ -8,14 +8,14 @@ namespace Android.Animation {
 
 	partial class Animator {
 
-		WeakReference dispatcher;
+		WeakReference? dispatcher;
 		AnimatorEventDispatcher Dispatcher {
 			get {
 				if (dispatcher == null || !dispatcher.IsAlive) {
 					dispatcher = new WeakReference (new AnimatorEventDispatcher ());
-					AddListener ((AnimatorEventDispatcher) dispatcher.Target);
+					AddListener ((AnimatorEventDispatcher) dispatcher.Target!);
 				}
-				return (AnimatorEventDispatcher) dispatcher.Target;
+				return (AnimatorEventDispatcher) dispatcher.Target!;
 			}
 		}
 
@@ -67,33 +67,33 @@ public AnimatorEventDispatcher ()
 			JNIEnv.FinishCreateInstance (Handle, "()V");
 		}
 
-		public EventHandler AnimationCancel;
-		public EventHandler AnimationEnd;
-		public EventHandler AnimationRepeat;
-		public EventHandler AnimationStart;
+		public EventHandler? AnimationCancel;
+		public EventHandler? AnimationEnd;
+		public EventHandler? AnimationRepeat;
+		public EventHandler? AnimationStart;
 
-		public void OnAnimationCancel (Animator animation)
+		public void OnAnimationCancel (Animator? animation)
 		{
 			var h = AnimationCancel;
 			if (h != null)
 				h (animation, EventArgs.Empty);
 		}
 
-		public void OnAnimationEnd (Animator animation)
+		public void OnAnimationEnd (Animator? animation)
 		{
 			var h = AnimationEnd;
 			if (h != null)
 				h (animation, EventArgs.Empty);
 		}
 
-		public void OnAnimationRepeat (Animator animation)
+		public void OnAnimationRepeat (Animator? animation)
 		{
 			var h = AnimationRepeat;
 			if (h != null)
 				h (animation, EventArgs.Empty);
 		}
 
-		public void OnAnimationStart (Animator animation)
+		public void OnAnimationStart (Animator? animation)
 		{
 			var h = AnimationStart;
 			if (h != null)

src/Mono.Android/Android.Animation/AnimatorSet.cs

@@ -17,19 +17,19 @@ public override Animator SetDuration (long duration)
 			if (base.GetType () == this.ThresholdType) {
 				return Java.Lang.Object.GetObject<AnimatorSet> (
 						JNIEnv.CallObjectMethod (base.Handle, id_setDuration_J, new JValue (duration)),
-						JniHandleOwnership.TransferLocalRef);
+						JniHandleOwnership.TransferLocalRef)!;
 			} else {
 				return Java.Lang.Object.GetObject<AnimatorSet> (
 						JNIEnv.CallNonvirtualObjectMethod (
 							base.Handle,
 							this.ThresholdClass,
 							JNIEnv.GetMethodID (ThresholdClass, "setDuration", "(J)Landroid/animation/Animator;"),
 							new JValue (duration)),
-						JniHandleOwnership.TransferLocalRef);
+						JniHandleOwnership.TransferLocalRef)!;
 			}
 		}
 
-		private static Delegate cb_setDuration_J;
+		private static Delegate? cb_setDuration_J;
 
 		private static Delegate GetSetDuration_JHandler ()
 		{
@@ -40,7 +40,7 @@ private static Delegate GetSetDuration_JHandler ()
 
 		private static IntPtr n_SetDuration_J (IntPtr jnienv, IntPtr native__this, long duration)
 		{
-			AnimatorSet @object = Java.Lang.Object.GetObject<AnimatorSet> (native__this, JniHandleOwnership.DoNotTransfer);
+			AnimatorSet @object = Java.Lang.Object.GetObject<AnimatorSet> (native__this, JniHandleOwnership.DoNotTransfer)!;
 			return JNIEnv.ToJniHandle (@object.SetDuration (duration));
 		}
 	}

src/Mono.Android/Android.Animation/FloatArrayEvaluator.cs

@@ -7,9 +7,9 @@ namespace Android.Animation
 {
 	public partial class FloatArrayEvaluator
 	{
-		Object ITypeEvaluator.Evaluate (float fraction, Object startValue, Object endValue)
+		Object ITypeEvaluator.Evaluate (float fraction, Object? startValue, Object? endValue)
 		{
-			return new JavaArray<float> (JNIEnv.NewArray<float> (Evaluate (fraction, (float []) (JavaArray<float>) startValue, (float []) (JavaArray<float>) endValue)), JniHandleOwnership.TransferLocalRef);
+			return new JavaArray<float> (JNIEnv.NewArray<float> (Evaluate (fraction, (float []?) (JavaArray<float>?) startValue, (float []?) (JavaArray<float>?) endValue)), JniHandleOwnership.TransferLocalRef);
 		}
 	}
 }

src/Mono.Android/Android.Animation/FloatEvaluator.cs

@@ -7,7 +7,7 @@ namespace Android.Animation
 {
 	public partial class FloatEvaluator
 	{
-		public virtual Object Evaluate (float fraction, Object startValue, Object endValue)
+		public virtual Object? Evaluate (float fraction, Object? startValue, Object? endValue)
 		{
 			return Evaluate (fraction, startValue.JavaCast<Number> (), endValue.JavaCast<Number> ());
 		}

src/Mono.Android/Android.Animation/IntArrayEvaluator.cs

@@ -7,9 +7,9 @@ namespace Android.Animation
 {
 	public partial class IntArrayEvaluator
 	{
-		Object ITypeEvaluator.Evaluate (float fraction, Object startValue, Object endValue)
+		Object ITypeEvaluator.Evaluate (float fraction, Object? startValue, Object? endValue)
 		{
-			return new JavaArray<int> (JNIEnv.NewArray<int> (Evaluate (fraction, (int []) (JavaArray<int>) startValue, (int []) (JavaArray<int>) endValue)), JniHandleOwnership.TransferLocalRef);
+			return new JavaArray<int> (JNIEnv.NewArray<int> (Evaluate (fraction, (int []?) (JavaArray<int>?) startValue, (int []?) (JavaArray<int>?) endValue)), JniHandleOwnership.TransferLocalRef);
 		}
 	}
 }

src/Mono.Android/Android.Animation/IntEvaluator.cs

@@ -7,7 +7,7 @@ namespace Android.Animation
 {
 	public partial class IntEvaluator
 	{
-		public virtual Object Evaluate (float fraction, Object startValue, Object endValue)
+		public virtual Object? Evaluate (float fraction, Object? startValue, Object? endValue)
 		{
 			return Evaluate (fraction, startValue.JavaCast<Integer> (), endValue.JavaCast<Integer> ());
 		}

src/Mono.Android/Android.Animation/PointFEvaluator.cs

@@ -7,9 +7,9 @@ namespace Android.Animation
 {
 	public partial class PointFEvaluator
 	{
-		Object ITypeEvaluator.Evaluate (float fraction, Object startValue, Object endValue)
+		Object? ITypeEvaluator.Evaluate (float fraction, Object? startValue, Object? endValue)
 		{
-			return Evaluate (fraction, (PointF) startValue, (PointF) endValue);
+			return Evaluate (fraction, (PointF?) startValue, (PointF?) endValue);
 		}
 	}
 }

src/Mono.Android/Android.Animation/RectEvaluator.cs

@@ -7,9 +7,9 @@ namespace Android.Animation
 {
 	public partial class RectEvaluator
 	{
-		Object ITypeEvaluator.Evaluate (float fraction, Object startValue, Object endValue)
+		Object? ITypeEvaluator.Evaluate (float fraction, Object? startValue, Object? endValue)
 		{
-			return Evaluate (fraction, (Rect) startValue, (Rect) endValue);
+			return Evaluate (fraction, (Rect?) startValue, (Rect?) endValue);
 		}
 	}
 }

src/Mono.Android/Android.Animation/ValueAnimator.cs

@@ -18,19 +18,19 @@ public override Animator SetDuration (long duration)
 			if (base.GetType () == this.ThresholdType) {
 				return Java.Lang.Object.GetObject<ValueAnimator> (
 						JNIEnv.CallObjectMethod (base.Handle, id_setDuration_J, new JValue (duration)),
-						JniHandleOwnership.TransferLocalRef);
+						JniHandleOwnership.TransferLocalRef)!;
 			} else {
 				return Java.Lang.Object.GetObject<ValueAnimator> (
 						JNIEnv.CallNonvirtualObjectMethod (
 							base.Handle,
 							this.ThresholdClass,
 							JNIEnv.GetMethodID (ThresholdClass, "setDuration", "(J)Landroid/animation/Animator;"),
 							new JValue (duration)),
-						JniHandleOwnership.TransferLocalRef);
+						JniHandleOwnership.TransferLocalRef)!;
 			}
 		}
 
-		private static Delegate cb_setDuration_J;
+		private static Delegate? cb_setDuration_J;
 
 		private static Delegate GetSetDuration_JHandler ()
 		{
@@ -41,7 +41,7 @@ private static Delegate GetSetDuration_JHandler ()
 
 		private static IntPtr n_SetDuration_J (IntPtr jnienv, IntPtr native__this, long duration)
 		{
-			ValueAnimator @object = Java.Lang.Object.GetObject<ValueAnimator> (native__this, JniHandleOwnership.DoNotTransfer);
+			ValueAnimator @object = Java.Lang.Object.GetObject<ValueAnimator> (native__this, JniHandleOwnership.DoNotTransfer)!;
 			return JNIEnv.ToJniHandle (@object.SetDuration (duration));
 		}
 	}

src/Mono.Android/Android.App.Admin/DevicePolicyManager.cs

@@ -8,7 +8,7 @@ namespace Android.App.Admin {
 
 	public partial class DevicePolicyManager {
 
-		public static DevicePolicyManager FromContext (Context context)
+		public static DevicePolicyManager? FromContext (Context context)
 		{
 			return context.GetSystemService (Context.DevicePolicyService) as DevicePolicyManager;
 		}

src/Mono.Android/Android.App/ActionBar.cs

@@ -10,24 +10,24 @@ partial class ActionBar {
 
 		public class TabEventArgs : EventArgs {
 
-			public TabEventArgs (FragmentTransaction fragmentTransaction)
+			public TabEventArgs (FragmentTransaction? fragmentTransaction)
 			{
 				FragmentTransaction = fragmentTransaction;
 			}
 
-			public FragmentTransaction FragmentTransaction {get; private set;}
+			public FragmentTransaction? FragmentTransaction {get; private set;}
 		}
 
 		partial class Tab {
 
-			WeakReference dispatcher;
+			WeakReference? dispatcher;
 			TabEventDispatcher Dispatcher {
 				get {
 					if (dispatcher == null || !dispatcher.IsAlive) {
 						dispatcher = new WeakReference (new TabEventDispatcher ());
-						SetTabListener ((TabEventDispatcher) dispatcher.Target);
+						SetTabListener ((TabEventDispatcher) dispatcher.Target!);
 					}
-					return (TabEventDispatcher) dispatcher.Target;
+					return (TabEventDispatcher) dispatcher.Target!;
 				}
 			}
 
@@ -71,25 +71,25 @@ public TabEventDispatcher ()
 			JNIEnv.FinishCreateInstance (Handle, "()V");
 		}
 
-		public EventHandler<ActionBar.TabEventArgs> TabReselected;
-		public EventHandler<ActionBar.TabEventArgs> TabSelected;
-		public EventHandler<ActionBar.TabEventArgs> TabUnselected;
+		public EventHandler<ActionBar.TabEventArgs>? TabReselected;
+		public EventHandler<ActionBar.TabEventArgs>? TabSelected;
+		public EventHandler<ActionBar.TabEventArgs>? TabUnselected;
 
-		public void OnTabReselected (ActionBar.Tab tab, FragmentTransaction ft)
+		public void OnTabReselected (ActionBar.Tab? tab, FragmentTransaction? ft)
 		{
 			var h = TabReselected;
 			if (h != null)
 				h (tab, new ActionBar.TabEventArgs (ft));
 		}
 
-		public void OnTabSelected (ActionBar.Tab tab, FragmentTransaction ft)
+		public void OnTabSelected (ActionBar.Tab? tab, FragmentTransaction? ft)
 		{
 			var h = TabSelected;
 			if (h != null)
 				h (tab, new ActionBar.TabEventArgs (ft));
 		}
 
-		public void OnTabUnselected (ActionBar.Tab tab, FragmentTransaction ft)
+		public void OnTabUnselected (ActionBar.Tab? tab, FragmentTransaction? ft)
 		{
 			var h = TabUnselected;
 			if (h != null)

src/Mono.Android/Android.App/Activity.cs

@@ -6,10 +6,10 @@ namespace Android.App {
 
 	partial class Activity {
 
-		public T FindViewById<T> (int id)
+		public T? FindViewById<T> (int id)
 			where T : Android.Views.View
 		{
-			return this.FindViewById (id).JavaCast<T> ();
+			return this.FindViewById (id)!.JavaCast<T> ();
 		}
 
 		public void StartActivityForResult (Type activityType, int requestCode)

src/Mono.Android/Android.App/ActivityManager.cs

@@ -6,7 +6,7 @@ namespace Android.App {
 
 	public partial class ActivityManager {
 
-		public static ActivityManager FromContext (Context context)
+		public static ActivityManager? FromContext (Context context)
 		{
 			return context.GetSystemService (Context.ActivityService) as ActivityManager;
 		}

src/Mono.Android/Android.App/ActivityTracker.cs

@@ -19,7 +19,7 @@ class ActivityTracker : Java.Lang.Object, Application.IActivityLifecycleCallback
 	{
 		readonly List<Activity> startedActivities = new List<Activity> ();
 
-		public event EventHandler ActivityStarted;
+		public event EventHandler? ActivityStarted;
 
 		public IReadOnlyList<Activity> StartedActivities {
 			get { return startedActivities; }
@@ -36,7 +36,7 @@ public void OnActivityStopped (Activity activity)
 			startedActivities.Remove (activity);
 		}
 
-		public void OnActivityCreated (Activity activity, Bundle savedInstanceState)
+		public void OnActivityCreated (Activity activity, Bundle? savedInstanceState)
 		{
 		}
 

src/Mono.Android/Android.App/AlarmManager.cs

@@ -6,7 +6,7 @@ namespace Android.App {
 
 	public partial class AlarmManager {
 
-		public static AlarmManager FromContext (Context context)
+		public static AlarmManager? FromContext (Context context)
 		{
 			return context.GetSystemService (Context.AlarmService) as AlarmManager;
 		}