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How can I test whether an Object implements a certain Interface that is
provided as Interface.class? I've tried the following:

====================================
boolean test(Object interfaceObj, Object testObj) {
//return true if testObj implements interfaceObj
}
test(MyInterface.class, someObj);
====================================

I think I've tried all variations of instance of and getClass() but
somehow I can't find the solution. The problem is with the fact that
I'm using MyInterface.class instead of an object.

Any suggestions?

Cheers,
cyberco

cyberco wrote:
> How can I test whether an Object implements a certain Interface that is
> provided as Interface.class? I've tried the following:
>
> ====================================
> boolean test(Object interfaceObj, Object testObj) {
//return true if testObj implements interfaceObj

return (testObje instanceof interfaceObj);
> }
> test(MyInterface.class, someObj);
> ====================================
>
> I think I've tried all variations of instance of and getClass() but
> somehow I can't find the solution. The problem is with the fact that
> I'm using MyInterface.class instead of an object.
>
> Any suggestions?
>
> Cheers,
> cyberco
>

Is it a requirement that testObj has to implement ALL the interfaces
interfaceObj implements?

Su Dang

cyberco wrote:
> How can I test whether an Object implements a certain Interface that is
> provided as Interface.class? I've tried the following:
>
> ====================================
> boolean test(Object interfaceObj, Object testObj) {
> //return true if testObj implements interfaceObj
> }
> test(MyInterface.class, someObj);
> ====================================
>
> I think I've tried all variations of instance of and getClass() but
> somehow I can't find the solution. The problem is with the fact that
> I'm using MyInterface.class instead of an object.
>
> Any suggestions?
>
> Cheers,
> cyberco

Coincidently I just bumped into what might be the solution:

========================

return interfaceObj.getClass().isAssignableFrom(testObj.g etClass());

========================

This tests whether interfaceObj is the same or a superclass/interface
of testObj. Quoting the API doc:

"Determines if the class or interface represented by this Class object
is either the same as, or is a superclass or superinterface of, the
class or interface represented by the specified Class parameter. It
returns true if so; otherwise it returns false. If this Class object
represents a primitive type, this method returns true if the specified
Class parameter is exactly this Class object; otherwise it returns
false."

I guess I learned something new today

Thanks,
cyberco

how about

return testObj.getClass().isInstance(interfaceObj);

Su Dang

that's the wrong way around (if I'm correct)

"cyberco" <> wrote in message
news: oups.com...
> Coincidently I just bumped into what might be the solution:
>
> ========================
>
> return interfaceObj.getClass().isAssignableFrom(testObj.g etClass());

No. Use instanceof.

cyberco wrote:
> How can I test whether an Object implements a certain Interface that is
> provided as Interface.class? I've tried the following:
>
> ====================================
> boolean test(Object interfaceObj, Object testObj) {
> //return true if testObj implements interfaceObj
> }
> test(MyInterface.class, someObj);
> ====================================
>
> I think I've tried all variations of instance of and getClass() but
> somehow I can't find the solution. The problem is with the fact that
> I'm using MyInterface.class instead of an object.
>
> Any suggestions?
>
> Cheers,
> cyberco
>

It would be easier if you could guarantee that the first test argument
is a Class:

boolean test(Class interfaceClass, Object testObj) {
return interfaceClass.isInstance(testObj);
}

In what cases will you need to call it with the interface NOT
represented by its Class?

Patricia

Patricia: actually, I CAN be sure that the method is always called with
a Class, so your suggestion (changing the interfaceClass parameter from
type Object to type Class) is indeed a good solution. Thanks for
pointing that out!