Fill arrays with ranges of numbers

Question

Is there any syntax/package allowing quick filling of java arrays with ranges of numbers, like in perl?

e.g.

int[] arr = new int[1000];
arr=(1..500,3         


        

Answer 1

As for the first question, whether it is possible to fill an array with the values of a range: it is actually possible to achieve that with the combination of Range, DiscreteDomain, ContiguousSet and Ints from Guava:

int[] array = Ints.toArray(
    ContiguousSet.create(Range.closed(1, 500), DiscreteDomain.integers()));

And, not exactly what is mentioned in the second part of the question, but it is possible to create a set with the elements of a range of a discrete domain:

Set<Integer> numbersFrom1To500 = 
    ContiguousSet.create(Range.closed(1, 500), DiscreteDomain.integers());

The resulting Set will not contain the specified elements physically, only logically (so it's memory footprint will be small), but can be iterated (since it's a Set):

for (Integer integer : numbersFrom1To500) {
    System.out.println(integer);
}

Answer 2

There is dollar:

// build the List 10, 11, 12, 13, 14
List<Integer> list2 = $(10, 15).toList();

maven:

<dependency>
        <groupId>org.bitbucket.dollar</groupId>
        <artifactId>dollar</artifactId>
        <version>1.0-beta3</version>
</dependency>

Answer 3

Another useful and not widely known Java 8 solution for existing arrays:

int[] array = new int[10];
Arrays.setAll(array, i -> i + 1);

Answer 4

    List<Integer> arrayOfRange  = new ArrayList<Integer>();
    int[] range = IntStream.iterate(1, n -> {arrayOfRange.add(n);return n + 1;}).limit(10).toArray();

// in addition to what craig answer if you want to have Integer 2nd approch

List<Integer> list = IntStream.of(range).boxed().collect(Collectors.toList());

Answer 5

For those still looking for a solution:

In Java 8 or later, this can be answered trivially using Streams without any loops or additional libraries.

int[] range = IntStream.rangeClosed(1, 10).toArray();

This will produce an array with the integers from 1 to 10.

A more general solution that produces the same result is below. This can be made to produce any sequence by modifying the unary operator.

int[] range = IntStream.iterate(1, n -> n + 1).limit(10).toArray();

Answer 6

Not quite as clean as True Soft's answer, but you can use Google Guava to the same effect:

public class Test {

    public static void main(String[] args) {
        //one liner
        int[] array = toArray(newLinkedList(concat(range(1, 10), range(500, 1000))));

        //more readable
        Iterable<Integer> values = concat(range(1, 10), range(500, 1000));
        List<Integer> list = newLinkedList(values);
        int[] array = toArray(list);

    }

    public static List<Integer> range(int min, int max) {
        List<Integer> list = newLinkedList();
        for (int i = min; i <= max; i++) {
            list.add(i);
        }

        return list;
    }

}

Note you need a few static imports for this to work.