Java 8 foreach 将子对象添加到新列表

Java 8 foreach add subobject to new list

提问by Valentin Grégtheitroade

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

是否可以在 Java 8 中编写如下内容：

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:

我认为它应该是以下几件事的混合：

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

or

或者

aList.forEach(bList::add);

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

但我不能混合这两者来获得所需的输出。

采纳答案by Bohemian

Here are a few ways

这里有几个方法

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:

或者您甚至可以bList()即时创建：

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