How can I make Cartesian product with Java 8 streams?

Question

I have the following collection type:

Map> map;

I would like to create unique combinations of each o

Answer 1

Use a Consumer Function Class, a List and a foreach

    public void tester(){

        String[] strs1 = {"2","4","9"};
        String[] strs2 = {"9","0","5"};

        //Final output is {"29", "49, 99", "20", "40", "90", "25", "45", "95"}
        List result = new ArrayList<>();
        Consumer consumer = (String str) -> result.addAll(Arrays.stream(strs1).map(s -> s+str).collect(Collectors.toList()));
        Arrays.stream(strs2).forEach(consumer);

        System.out.println(result);

}