arraylist - How to zip two Java Lists

Question

I have 2 Lists:

List<String> subjectArr = Arrays.asList<String>("aa", "bb", "cc");
List<Long> numArr = Arrays.asList<Long>(2L, 6L, 4L);

How do I create new List and zip two Lists into it?

List<?> subjectNumArr = zip(subjectArr, numArr);
// subjectNumArr == [{'aa',2},{'bb',6},{'cc',4}]

Answer 1

Here's Java-8 solution using the Pair class (like in @ZhekaKozlov answer):

public static <A, B> List<Pair<A, B>> zipJava8(List<A> as, List<B> bs) {
    return IntStream.range(0, Math.min(as.size(), bs.size()))
            .mapToObj(i -> new Pair<>(as.get(i), bs.get(i)))
            .collect(Collectors.toList());
}

In Java 9 onwards you can use Map.entry():

    public static <A, B> List<Map.Entry<A, B>> zipJava8(List<A> as, List<B> bs) {
        return IntStream.range(0, Math.min(as.size(), bs.size()))
                .mapToObj(i -> Map.entry<>(as.get(i), bs.get(i)))
                .collect(Collectors.toList());
    }