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

Andrej Golovnin andrej.golovnin at gmail.com
Mon Jun 9 19:56:36 UTC 2014

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

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