Making a copy of an array with Arrays.asList

Question

so I have an int array, and want to have another array that points to the same values as the original array so that when original array changes the second array would point to to the new value.

I tried with

List<Integer> secondList = new ArrayList<>(Arrays.asList(original array));
secondList = secondList.subList(start,finish);

But I get an error that says that .asList returns - list of type int[] Am I doing something wrong? Or is there any good way to do this?

let me guess: the original array is decleared as `int[]`? Try declaring it as `Integer[]` — Turing85, Apr 19 '15 at 16:38
@AnubianNoob I do not understand... just like every other array: `Integer[] array = new Integer[size];`. You have to initialize each cell with `array[i] = new Integer(value);`. — Turing85, Apr 19 '15 at 16:40
You don't need to copy then, you just to create a new reference. — Boris the Spider, Apr 19 '15 at 16:45

score 0 · Accepted Answer · answered Apr 19 '15 at 16:38

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If the original array is int[], Arrays.asList will return a List<int[]>. If the original array will be Integer[], Arrays.asList will return a List<Integer>.

answered Apr 19 '15 at 16:38

Eran

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score 0 · Answer 2 · answered Apr 19 '15 at 16:43

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You can just make the second list point to the first with the use of the "=" operator.

For example:

List<Integer> firstList = new ArrayList<Integer>();
List<Integer> secondList = firstList;

firstList.add(1);
System.out.println(secondList.size());

Will print out "1" as the size of the second list as they both "point" to the same location in memory.

answered Apr 19 '15 at 16:43

Tech Lobster

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The first `ist` is not a list, but an array. Therefore, you solution will not work. – Turing85 Apr 19 '15 at 16:44

Making a copy of an array with Arrays.asList

2 Answers2