根据另一个列表从列表中过滤元素 [英] Filter Elements from a list based on another list

问题描述

我想在 Java 8

我有布尔列表和另一个对象列表，这两个列表的大小始终相同。我想删除 object 列表中的所有元素，它们在 false > boolean list。

I have a Boolean list and another Object list, size of these two lists is always same. I want to remove all the elements from object list, which have false at the corresponding index in boolean list.

我将尝试用一个例子来解释：

I will try to explain with an example:

objectList = {obj1,obj2,obj3,obj4,obj5};
booleanList = {TRUE,FALSE,TRUE,TRUE,FALSE};

所以从这些列表中，我想更改 objectList 来

So from these list, I want to change objectList to

{obj1,obj3,obj4}// obj2 and obj5 are removed because corresponding indices are `FALSE` in `booleanList`.

如果我在 Java 7中执行此操作，我会做以下事情：

If I have have do this in Java 7, I would do the following :

List<Object> newlist = new ArrayList<>();
for(int i=0;i<booleanList.size();i++){
    if(booleanList.get(i)){
        newList.add(objectList.get(i));
    }
}
return newList;

有没有办法在 Java 8中执行此操作代码较小？

Is there a way to do this in Java 8 with lesser code?

推荐答案

您可以使用 IntStream 来生成索引，然后过滤器获取过滤后的索引， mapToObj 获取相应的对象：

You can use an IntStream to generate the indices, and then filter to get the filtered indices and mapToObj to get the corresponding objects :

List<Object> newlist =
    IntStream.range(0,objectList.size())
             .filter(i -> booleanList.get(i))
             .mapToObj(i -> objectList.get(i))
             .collect(Collectors.toList());

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