Casting an Array of Integers into a Long

Question

I am trying to typecast an integer array into a long array, but I don't quite know how to go about doing this.

So far, my code looks like this:

import java.util.Random;

public class main {

public static int[] sect(){
    int[] returned = new int[4];
    Random rand = new Random();
    returned[0] = 4;
    returned[1] = rand.nextInt(8) + 1;
    returned[2] = rand.nextInt(7) + 1;
    returned[3] = rand.nextInt(6) + 1;

    return returned;
}

public static String num(){
    for (int j = 0; j < 4; j++) {
        int[] ints = sect();
        for(int i =0; i < ints.length; i++) {
            System.out.print(ints[i]);
        }
    }
    return null;
}
}

I have tried doing things like:

return ((long)num());

But that never works. Does anyone know how I would go about doing this?

You can't cast an array of primitives into one primitive. What operations do you want to do to the `int`s to transform them into a `long`? — Jacob G., May 05 '17 at 03:37
The method `num()` returns a `String` - and you can't cast a `String` to a `long`. — Jason, May 05 '17 at 03:52
*Does anyone know how I would go about doing this?* Doing what? You haven't explained what you're trying to do. — shmosel, May 05 '17 at 03:57
Unaccepting an answer is perfectly fine, but I would ask you to at least consider upvoting those answer(s) you deem helpful to you. You can accept only one answer, but upvote as much as you want to. — GhostCat, May 07 '17 at 09:28

GhostCat · Answer 1 · 2017-05-08T03:46:54.737

1

You can't do that.

You simply have to create an equal sized array, and copy the int values into that array. Unfortunately System.arraycopy() can not do that for you... So you can't avoid the manual copying here.

Because an array of int isn't an array of longs. Therefore there is no such cast as from a single int into a single long.

edited May 08 '17 at 03:46

answered May 05 '17 at 03:51

GhostCat

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score 1 · Accepted Answer · answered May 05 '17 at 04:19

1

Are you using Java 8, if so this will work:

int[] arrayOfIntegers = {1, 2, 3, 4, 5, 6};

long[] arrayOfLongs = Arrays.stream(arrayOfIntegers).mapToLong(i -> i).toArray();

answered May 05 '17 at 04:19

jasonlam604

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https://docs.oracle.com/javase/8/docs/api/java/util/stream/IntStream.html#asLongStream-- – shmosel May 05 '17 at 04:23
@GhostCat I don't think you can use `System.arraycopy()` with different array types. – shmosel May 08 '17 at 03:43

Casting an Array of Integers into a Long

2 Answers2