RFR 9 and 8u: JDK-8029674: (reflect) getMethods returns default methods that are not members of the class

[Andrej Golovnin]

Hi Joel,

> IIRC name isn’t actually interned with String.intern() but in the VM:s Symbol table as a name representing a (Java) method. Should be equivalent, as long as we don’t start comparing it with == with interned Strings.

I think that's not true.

The following small test program prints true on the console:

public class Test {

    public static void main(String... argv) throws Exception {
        Method m = Test.class.getMethod("main", String[].class);
        System.out.println(m.getName() == new String("main").intern());
    }

}

And if you look into reflection.cpp at lines 787-789, you will see following code:

  Symbol*  method_name = method->name();
  oop name_oop = StringTable::intern(method_name, CHECK_NULL);
  Handle name = Handle(THREAD, name_oop);

And later at the line 798 we have this code:

  java_lang_reflect_Method::set_name(mh(), name());

Therefore I would say the name is actually interned in terms of String.intern().
And you can compare the name of a method with == with interned Strings.

The same applies to a name of a class and to a name of a field too.
Please feel free to correct me.

Best regards,
Andrej Golovnin


> 
> cheers
> /Joel
> 
> On 07 Jun 2014, at 22:34, Andrej Golovnin <andrej.golovnin at gmail.com> wrote:
> 
>> Hi Joe,
>> 
>>> Sorry for the belated review.
>>> 
>>> Generally the change looks good. One question, in
>>> 
>>> 2803         private boolean matchesNameAndDescriptor(Method m1, Method m2) {
>>> 2804             return m1.getReturnType() == m2.getReturnType() &&
>>> 2805                    m1.getName() == m2.getName() &&
>>> 2806                    arrayContentsEq(m1.getParameterTypes(),
>>> 2807                            m2.getParameterTypes());
>>> 2808         }
>>> 
>>> Should the equality check on 2805 be .equals rather than == ?
>>> 
>> 
>> "==" can be used in this case as the method name is interned by JVM. 
>> Here is the comment for the field "name" from java.lang.reflect.Method:
>> 
>>  // This is guaranteed to be interned by the VM in the 1.4
>>  // reflection implementation
>>  private String              name;
>> 
>> BTW, in the old version of Class in the line 2766 there was already a similar check:
>> 
>> 2764                 if (m != null &&
>> 2765                     m.getReturnType() == toRemove.getReturnType() &&
>> 2766                     m.getName() == toRemove.getName() &&
>> 2767                     arrayContentsEq(m.getParameterTypes(),
>> 2768                                     toRemove.getParameterTypes())) {
>> 2769                     methods[i] = null;
>> 
>> 
>> Best regards,
>> Andrej Golovnin
>> 
>> 
>