Java 8 foreach add subobject to new list

Question

Is it possible in Java 8 to write something like this:

List<A> aList = getAList();
List<B> bList = new ArrayList<>();

for(A a : aList) {
    bList.add(a.getB());
}

I think it should be a mix of following things:

aList.forEach((b -> a.getB());

or

aList.forEach(bList::add);

But I can't mix these two to obtain the desired output.

Bohemian · Accepted Answer · 2016-10-01 12:50:02Z

46

Here are a few ways

aList.stream().map(A::getB).forEach(bList::add);
// or
aList.forEach(a -> bList.add(a.getB()));

or you can even create bList() on the fly:

List<B> bList = aList.stream().map(A::getB).collect(Collectors.toList());

answered Oct 1, 2016 at 12:50

Bohemian♦

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