instanceof operator

[Rippon Jalali]

i want to ask a question that whether we can use instanceof operator with arrays?

[Ajay Singh]

sure, if you want to check of array is instanceof int[], use this

if(array instanceof int[].class) {
}

[Ernest Friedman-Hill]

Originally posted by Ajay Singh:

if(array instanceof int[].class)

That should be

if (array instanceof int[]) ...

[Ajay Singh]

thanks for correction!

[John Bartlett]

just wondering whether there is a way to compare instances of two objects

e.g.

    
 if (obj1 instanceof obj2) {
         return true
 }

cheers,

John

[Ajay Singh]

you can't compare the way have done below. Howerver, you can use something like:

if(obj1.getClass().isAssignableFrom(obj2.getClass()) {
    
}

[Christopher Elkins]

It is exactly how you stated;

if (obj1 instanceof obj2)
{
  return true;
}

[Ernest Friedman-Hill]

Originally posted by Christopher Elkins:
[QB]It is exactly how you stated;

No, it's not. The second argument to instanceof is the literal name of a class, not variable data of any kind, and certainly not an object.

[fred rosenberger]

This doesn't make sense to me:

if (obj1 instanceof obj2)

that's like saying

if (fred instanceof satchmo)

what kind of object is fred? is satchmo? fred is an instance of Person, but satchmo is an instance of FredsCat.

unless your in a jazz music program, then satchmo could be a Person.

You can only have an instance of a class (or interface).

I think what you are trying to get at is, given two object references, you want to know if they are of the same type. Is that what you are asking?
[ January 08, 2007: Message edited by: Fred Rosenberger ]

[Rippon Jalali]

actually the question was like this
# instanceof operator can be used with ...

1. interfaces
2. Arrays
3. Classes
4. All of the above

so should answer be the (4)

[Ajay Singh]

Yes, the right hand should be any type, interface, array, class

[Rippon Jalali]

i checked it for:
if(array instanceof int[]).
it is working .And ofcourse the answer should be (4).Thank you for your response

[John Bartlett]

Yes that is what i meant, my method gets passed two Objects and i want to be able to tell whether they are the same type.