How to convert map <Shape, int []> to Map <Shape, Set <Integer>> in Java 8?

Question

I am new to Java 8 and I have the following requirement for conversion:

Map<Shape, int[]> --> Map<Shape, Set<Integer>>

Any ideas?

Answer 1

I edited the question in the hope that Set<Integer>- this is what you really need, because you cannot have a primitive Settype Set<int>.

 map.entrySet()
            .stream()
            .collect(Collectors.toMap(
                    Entry::getKey,
                    x -> Arrays.stream(x.getValue()).boxed().collect(Collectors.toSet())

    ));

On the other hand, if you really want a unique primitives, then they will work distinctand toArray, but will still type Map<Shape, int[]>:

 map.entrySet()
            .stream()
            .collect(Collectors.toMap(
                    Entry::getKey,
                    x -> Arrays.stream(x.getValue()).distinct().toArray()

    ));

Answer 2

The following is a method to convert an array intto Set<Integer>:

private Set<Integer> convertArrayToSet(int[] array) {
    return stream(array).boxed().collect(toSet());
}

You need to skip each map value using this method:

public Map<Shape, Set<Integer>> convert(Map<Shape, int[]> map) {
    return map.entrySet()
            .stream()
            .collect(toMap(e -> e.getKey(), e -> convertArrayToSet(e.getValue())));
}

Arrays, Collectors, .