Originally Posted by priti_s

Hi
I have come across a question in a collection which says:
One can add a reference of a collection to itself. Is it true or false?
I read the explanation that, we can add the reference to the collection to itself, but it results in the stack overflow of the JVM. Please people tell me what is the correct answer, i am confused because we can add the reference but we should not add it.
Please help me

Originally Posted by Alex Edwards

Ok, let me see if I understand what you're asking.

Let's first determine what a collection is.

Collection (programming) - a structure that holds many objects of some type (in old versions of Java, collections stored arbitrary objects, and in new versions you can specify a Generic collection that is 'at least' the type specified).

Reference (programming) - An address of the underlying object.

So can we add a Reference of a Collection to a Collection? Sure you can. I believe that is called a composite structure, though I'm no professional so I could be wrong =P

Help with Code Tags

java Syntax (Toggle Plain Text)

 
/*Declare an ArrayList that can store Object references*/
ArrayList<Object> myArrayList = new ArrayList<Object>(0);
 
// ... some time later in code...
 
/*Adding the address of the ArrayList itself to itself*/
myArrayList.add(myArrayList);

/*Declare an ArrayList that can store Object references*/ ArrayList<Object> myArrayList = new ArrayList<Object>(0); // ... some time later in code... /*Adding the address of the ArrayList itself to itself*/ myArrayList.add(myArrayList);

--the only way you can make a collection overflow is if you are creating a custom collection and you attempt to declare a globally scoped Reference to a collection that is the same class (or a derived class) of the class you are defining and use eager-instantiation, or possibly Constructor-instantiation of the collection-reference itself.

You can, instead, provide a way to dynamically set your Collection reference to prevent a stack-overflow.

Originally Posted by priti_s

Hey, thanks, but from exam point of view, what shall i write True or False? From examples it is clear that surely we can add, but it's not recommended, isn't it? So shall i go with option "True"?

Originally Posted by priti_s

Hey, thanks, but from exam point of view, what shall i write True or False? From examples it is clear that surely we can add, but it's not recommended, isn't it? So shall i go with option "True"?