What is a shallow copy of the array

Question

When you call the clone () method on an ArrayList, a shallow copy of the list is created. what is a shallow copy of an array?

Answer 1

You must distinguish between two types of copies: shallow and deep .

While a deep copy allocates a new space for the entire array and all its contents (if it contains links, then a new space is allocated for creating instances with the same values ​​of the copied), a shallow copy simply allocates space with the same size of the copied array.

Example:

Array A was allocated to contain only two mutable objects (for example: a list or arraylist), you want to have only a copy of the "extern" array (one that contains two links), or you need a deep copy that will also highlight new instances of the two links contained in A?

In the first case, for example:

A is an array starting with reference 0x0000AA

ElementOne starts at 0x00BBCC

ElementTwo starts at 0x00BBFF

If you do a shallow copy:

B (new array) starts at 0x0000BB, ElementsOne and ElementsTwo will point to old links (0x00BBCC, 0x00BBFF).

If you are doing a deep copy, it not only allocates new space for the array, but also allocates space for storing new instances (new list, new arraylist ...).

Answer 2

If you have links in an ArrayList, the same links will be copied to the cloned ArrayList. Objects will not be cloned.

Answer 3

Only array elements are copied. If they are reference types, only the link is copied. Any subtypes or elements of the object that are behind the link are not copied.