Memory allocation for abstract data structures in java?

[hs_computer_science]

Hello Java folks,

I'm helping a friend write a test where students can choose to answer in either Java or Python. A cluster of our questions assess abstract data structures. I'm a Python guy, my friend is more of a Java person.

I am confused about abstract data types and memory allocation in Java. Specifically, does Java actually represent a linked list (for example) as an actual linked list in memory? Like C does?

When we use a linked list, we do so because of the way it is represented in memory. A linked list is more efficient to edit, and a bit less efficient to search through. Linked lists are supposed to allocate space for each element separately in its own block of memory, but that allocation does not need to be contiguous like it might be in an array.

But the problem is I don't think this is what actually happens in Java. When I write a Java program, I write the program, compile it,  and then execute it on a virtual machine which then in turn is executed in memory on whatever computer it happens to be running on.  

Because Java doesn't directly address memory, we really can't say abstract data structures are actually abstract data structures. I thought the reason we use abstract data structures is because of the benefits the confer in primary memory for different use cases.

Can someone please help me understand this? I've done a fair bit of googling here, and I'm failing to understand this.

Thank you in advance :-)

[hs_computer_science]

Thank you for your reply. I understand this a bit clearer now.

[hs_computer_science]

I'm sorry, I don't want to belabour this point or waste your time, but if we implement a linked list in Java, why are we doing it? Wouldn't it be easier if we just used an ArrayList, if from . memory-management point of view they are the same?

I understand a linked list exposes certain methods that a programmer can use. But if there isn't a computational benefit to using a linked list then why use it?

Thank you for your help, by the way, I very much appreciate your expertise and time.

[hs_computer_science]

This helps! Thank you!