[Android] Internal keyboard hide/show should handle null views (#418)

* Check for null input view before trying to hide keyboard

* Adding null check to ShowKeyboard

* change to throw an exception

1 files changed, 7 insertions, 3 deletions

diff --git a/Xamarin.Forms.Platform.Android/KeyboardManager.cs b/Xamarin.Forms.Platform.Android/KeyboardManager.cs
index bfe65d13..eb89731b 100644
--- a/Xamarin.Forms.Platform.Android/KeyboardManager.cs
+++ b/Xamarin.Forms.Platform.Android/KeyboardManager.cs
@@ -14,14 +14,15 @@ namespace Xamarin.Forms.Platform.Android
 			if (Forms.Context == null)
 				throw new InvalidOperationException("Call Forms.Init() before HideKeyboard");
 
+			if (inputView == null)
+				throw new ArgumentNullException(nameof(inputView) + " must be set before the keyboard can be hidden.");
+
 			using (var inputMethodManager = (InputMethodManager)Forms.Context.GetSystemService(Context.InputMethodService))
 			{
-				IBinder windowToken = null;
-
 				if (!overrideValidation && !(inputView is EditText || inputView is TextView || inputView is SearchView))
 					throw new ArgumentException("inputView should be of type EditText, SearchView, or TextView");
 
-				windowToken = inputView.WindowToken;
+				IBinder windowToken = inputView.WindowToken;
 				if (windowToken != null)
 					inputMethodManager.HideSoftInputFromWindow(windowToken, HideSoftInputFlags.None);
 			}
@@ -32,6 +33,9 @@ namespace Xamarin.Forms.Platform.Android
 			if (Forms.Context == null)
 				throw new InvalidOperationException("Call Forms.Init() before ShowKeyboard");
 
+			if (inputView == null)
+				throw new ArgumentNullException(nameof(inputView) + " must be set before the keyboard can be shown.");
+
 			using (var inputMethodManager = (InputMethodManager)Forms.Context.GetSystemService(Context.InputMethodService))
 			{
 				if (inputView is EditText || inputView is TextView || inputView is SearchView)