Use Method.getParameterCount() where possible

[Christoph Dreis]

Hi,

I noticed that the JDK itself still uses Method.getParameterTypes().length in a 
couple of places.

This could be replaced with Method.getParameterCount() to avoid unnecessary 
cloning overhead.
While this is often optimized away, I guess it's still good to not rely on 
that. Additionally, it's a little more concise to read.

If you think this is worthwhile, I would need someone to sponsor that tiny 
change.

P.S.: There is another occurrence in ForkJoinTask where I wasn't sure if I 
should change that, because it's usually changed under the JSR166 umbrella 
afaik.

Cheers,
Christoph

==== PATCH ====

diff --git 
a/src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java 
b/src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java
--- a/src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java
+++ b/src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java
@@ -276,13 +276,13 @@
         switch (m.getName()) {
         case "toString":
             return (m.getReturnType() == String.class
-                    && m.getParameterTypes().length == 0);
+                    && m.getParameterCount() == 0);
         case "hashCode":
             return (m.getReturnType() == int.class
-                    && m.getParameterTypes().length == 0);
+                    && m.getParameterCount() == 0);
         case "equals":
             return (m.getReturnType() == boolean.class
-                    && m.getParameterTypes().length == 1
+                    && m.getParameterCount() == 1
                     && m.getParameterTypes()[0] == Object.class);
         }
         return false;
diff --git a/src/java.base/share/classes/java/lang/reflect/Executable.java 
b/src/java.base/share/classes/java/lang/reflect/Executable.java
--- a/src/java.base/share/classes/java/lang/reflect/Executable.java
+++ b/src/java.base/share/classes/java/lang/reflect/Executable.java
@@ -378,7 +378,7 @@
     private void verifyParameters(final Parameter[] parameters) {
         final int mask = Modifier.FINAL | Modifier.SYNTHETIC | 
Modifier.MANDATED;

-        if (getParameterTypes().length != parameters.length)
+        if (getParameterCount() != parameters.length)
             throw new MalformedParametersException("Wrong number of parameters 
in MethodParameters attribute");

         for (Parameter parameter : parameters) {
diff --git 
a/src/java.base/share/classes/sun/reflect/annotation/AnnotationType.java 
b/src/java.base/share/classes/sun/reflect/annotation/AnnotationType.java
--- a/src/java.base/share/classes/sun/reflect/annotation/AnnotationType.java
+++ b/src/java.base/share/classes/sun/reflect/annotation/AnnotationType.java
@@ -121,7 +121,7 @@
             if (Modifier.isPublic(method.getModifiers()) &&
                 Modifier.isAbstract(method.getModifiers()) &&
                 !method.isSynthetic()) {
-                if (method.getParameterTypes().length != 0) {
+                if (method.getParameterCount() != 0) {
                     throw new IllegalArgumentException(method + " has params");
                 }
                 String name = method.getName();