Creating new array

Question

The question is very simple. Is any simple and fast way to create new (new references) array or it has to be done manually?

Example:

Collection<A> c = new ArrayList<A>();
c.add(new A());
c.add(new A());
c.add(new A());

A[] a1 = c.toArray(new A[0]);
System.out.println("a1: " + Arrays.toString(a1));
System.out.println("c: " + c);

A[] a2 = Arrays.copyOf(a1, a1.length);
System.out.println("a2: " + Arrays.toString(a2));

All created arrays has the same references. I want array with new elements with the same content as old elements. Copies of old elements.

Answer is: How do you make a deep copy of an object in Java? . Now I see that this question is duplicate.

Not sure if I understand the question: do you mean you want a deep copy instead of a shallow copy? — jlordo
– jlordo, Commented Sep 2, 2013 at 16:20
Is this a shallow clone (in which just the collection is new) or a deep clone (in which the actual objects in the collection are copied — Richard Tingle
– Richard Tingle, Commented Sep 2, 2013 at 16:21
Deep copies are expensive. Generally I write code so I never need to do that. — Peter Lawrey
– Peter Lawrey, Commented Sep 2, 2013 at 16:24
Please check if this helps you out: javatechniques.com/blog/faster-deep-copies-of-java-objects got from: stackoverflow.com/questions/64036/… — Natan Streppel
– Natan Streppel, Commented Sep 2, 2013 at 16:26

Community · Accepted Answer · 2017-05-23 10:25:17Z

1

If you want to create a deep copy of the array (meaning: with freshly created references to each of its elements), there are several alternatives, including:

Serialize/deserialize the array (see Apache's SerializationUtils)
Manually copying each element (and that element's attributes, recursively)
Using reflection explicitly
Using a copy constructor

... And so on. Look in stack overflow, there are several posts discussing the subject.

edited May 23, 2017 at 10:25

CommunityBot

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answered Sep 2, 2013 at 16:28

Óscar López

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