java 同时迭代两个列表并使用流创建另一个列表
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Iterate two lists simultaneously and create another using streams
提问by ParagJ
I want to achieve following using streams:
我想使用流实现以下目标:
List<MyObject> list1 = Arrays.asList(obj1, obj2, obj3);
List<Boolean> list2 = Arrays.asList(true, false, true);
List<MyObject> list = new ArrayList<>();
for(int i=0; i<list1.size();i++) {
if(list2.get(i))
list.add(list1.get(i));
}
Can anyone help? It should be easy but I am new to java streams.
任何人都可以帮忙吗?这应该很容易,但我是 Java 流的新手。
Note:The length of list1 and list2 would be same always.
注意:list1 和 list2 的长度总是相同的。
回答by user158037
You could do something like:
你可以这样做:
List<MyObject> list = IntStream.range(0, list1.size())
.filter(i->list2.get(i))
.map(i->list1.get(i))
.collect(Collectors.toList())
It could be better if Java had build-in zip
for streams. For example with Guava you can use:
如果 Java 内置zip
了流,那就更好 了。例如,您可以使用番石榴:
Streams.zip(list2.stream(), list1.stream(), (a,b) -> a ? b : null)
.filter(Objects::nonNull)
.collect(Collectors.toList())