[Java.Interop] Add JniType.AllocObject(), GetCachedInstanceMethod().

Author: jonpryor

src/Java.Interop/Java.Interop/JniType.cs

@@ -1,8 +1,6 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Reflection;
-using System.Text;
+using System.Threading;
+
 using Java.Interop;
 
 namespace Java.Interop {
@@ -30,6 +28,11 @@ public JniInstanceMethodID GetConstructor (string signature)
 			return JniMembers.GetMethodID (SafeHandle, "<init>", signature);
 		}
 
+		public JniLocalReference AllocObject ()
+		{
+			return JniActivator.AllocObject (SafeHandle);
+		}
+
 		public JniLocalReference NewObject (JniInstanceMethodID constructor, params JValue[] @params)
 		{
 			return JniActivator.NewObject (SafeHandle, constructor, @params);
@@ -39,5 +42,15 @@ public JniInstanceMethodID GetInstanceMethod (string name, string signature)
 		{
 			return JniMembers.GetMethodID (SafeHandle, name, signature);
 		}
+
+		public JniInstanceMethodID GetCachedInstanceMethod (ref JniInstanceMethodID cachedMethod, string name, string signature)
+		{
+			if (cachedMethod != null && !cachedMethod.IsInvalid)
+				return cachedMethod;
+			var m = GetInstanceMethod (name, signature);
+			if (Interlocked.CompareExchange (ref cachedMethod, m, null) != null)
+				m.Dispose ();
+			return cachedMethod;
+		}
 	}
 }