Java LinkedList 默认是浅拷贝还是深拷贝？

Question

I am confused on whether linked list node is shallow copy or deep copy by default. For example, when we have following code:

ListNode left = new ListNode(0);
ListNode temp = left;

temp.next = new ListNode(3);
temp = temp.next;

Will this statement temp = temp.next also change the node left to temp.next as well? Why?

Answer 1

Java is not C++ which will copy the instances which are constructed on stack memory. So all Java objects are created on heap memory, so there won't happen any copying task.

I think you are coming from C++, which in C++ the object it was created on stack memory will happen copy when you are passing it as parameters or assigning to other variables except if you created with new keyword. But the Java objects are usually created on the heap and so there will not happen any copying task. So be relax with Java objects, but be careful with C++ objects (on the stack)

Answer 2

It's neither -- there's no copying going on here, and perhaps you are confusing references with copies, as they are two different things. Each node holds a reference to the next node, if it exists, or to null, if it doesn't.

A "copy" is where you create an entirely new instance of a type, one that copies the state of an existing instance of the same type, shallow if the new instance contains the reference fields that hold the exact same references of the original and deep if the new instance's reference fields contain new instances that have the same state as the original's, .... but nowhere in your question are you creating new copy instances, deep or shallow.