How to Duplicate an array list in Java?

Question

I have an array list that stores objects called Movie. The objects contain variables such as name , date released ,genre etc.. Is there a way to duplicate the array so I can sort it one by one keep the original data unchanged. I will be displaying the data in text areas.

I think you can use `clone` to duplicate arraylist and create a new with the same data inside it, by this way you will be able to save the memory and a good solution without compromising performance. — Pankaj Dubey, May 06 '15 at 10:58

score 6 · Accepted Answer · answered May 06 '15 at 10:59

6

Use

List<Movie> newList = new ArrayList<>(existingList);

answered May 06 '15 at 10:59

Tagir Valeev

92,683
18
210
320

score 1 · Answer 2 · answered May 06 '15 at 10:59

You can create a copy of the old ArrayList with:

List<Movie> newList = new ArrayList<Movie>(oldList);

You should know that this creates a shallow copy of the original ArrayList, so all of the objects in both lists will be the same, but the two lists will be different objects.

score 0 · Answer 3 · answered May 06 '15 at 10:59

0

Though the question is ambiguous, you can use

List<Integer> newList = new ArrayList<Integer>(oldList); to copy an old List

and

Arrays.copyOf() to copy array.

answered May 06 '15 at 10:59

Aakash

1,915
13
22

score 0 · Answer 4 · answered May 06 '15 at 11:00

0

System.arraycopy()

public static void arraycopy(Object src, int srcPos, Object dest, int destPos, int length)

Source

answered May 06 '15 at 11:00

KM11

695
6
15

score 0 · Answer 5 · 2015-05-06T11:24:13.003

Every Collection Class provide a constructor to crate a duplicate collection Object.

List<Movie> newList = new ArrayList<Movie>(oldList);

since newList and oldList are different object so you can also create a clone of this object-

public static List<Movie> cloneList(List<Movie> oldList) {
    List<Movie> clonedList = new ArrayList<Movie>(oldList.size());
    for (Movie movie: oldList) {
        clonedList.add(new Movie(movie));
    }
    return clonedList;
}

ArrayList is also dynamic array,but if you want to store this in array you can do this as-

int n=oldList.size();
Movie[] copiedArray=new Movie[n];

for (int i=0;i<oldList.size();i++){
copiedArray[i]=oldList.get(i);
}

score 0 · Answer 6 · answered May 06 '15 at 11:13

0

You can get Array from original Array List as below:

Movie movieArray[] = arrayListMovie
    .toArray(new Movie[arrayListMovie.size()]);

answered May 06 '15 at 11:13

Rajesh

2,120
1
11
14

How to Duplicate an array list in Java?

6 Answers6