Populate list of multiples using stream

Question

Is there a way to write this method in a Java 8 declarative style, using stream()?

public List<Integer> getFives(int numberOfElements, int incrementNum) {
    List<Integer> list;
    int value = incrementNum;
    list.add(value);
    for (int i = 0; i < numberOfElements; i++) {
        value = value + incrementNum;
        list.add(value);
    }
    return list;
}

Your current code does not compile. What do you what to achieve? And what have you tried? — Rob Audenaerde, Mar 26 '20 at 10:23

Eritrean · Accepted Answer · 2020-03-26T10:57:37.603

2

There are many ways to achieve what you want, one of them is using Intstream#iterate :

public static  List<Integer> getFives(int numberOfElements, int incrementNum) {    
    return IntStream.iterate(incrementNum, i -> i+incrementNum)
                    .limit(numberOfElements)
                    .boxed()
                    .collect(Collectors.toList());
}

edited Mar 26 '20 at 10:57

answered Mar 26 '20 at 10:29

Eritrean

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1

according to the code in question, choose seed as `incrementNum` – Naman Mar 26 '20 at 10:48

score 1 · Answer 2 · answered Mar 26 '20 at 10:44

You seem to be looking for multiples as:

public List<Integer> getMultiples(int numberOfElements, int incrementNum) {
    return IntStream.rangeClosed(1, numberOfElements)
            .mapToObj(i -> i * incrementNum)
            .collect(Collectors.toList());
}

Populate list of multiples using stream

2 Answers2