"I'd also like to tell you a couple of interesting things about object lifetime. In Java, it's very difficult to accidentally destroy an object. If you have a reference to an object, it is alive.

You can't change references to an object, and you can't increase or decrease them. Additionally, you can't create a reference to an object. You can only assign a reference or set it to null."

"I think I understand, Ellie. So if I erase (or set to null) all references to an object, then I'll never again be able to get a reference to that object or access it, right?"

"That's correct. However, you can also have the situation where the system has too many live objects that are not being used. Programmers often create dozens of objects, store them in various lists for processing, and then never empty these lists.

Objects that programmers don't need are usually simply marked as eligible for garbage collection. Nobody deletes them from lists. As a result, large Java programs often become too big as more and more unused objects remain in memory.

You won't run into this soon, but every time I'll remind you about these unused objects, as well as the right way to dispose of them."

"OK. Thank you, Ellie, for helping me better understand references."