两个列表中的公共元素
问题描述：
我有两个 ArrayList 对象，每个对象有三个整数.我想找到一种方法来返回两个列表的公共元素.有人知道我如何实现这一目标吗?
I have two ArrayList objects with three integers each. I want to find a way to return the common elements of the two lists. Has anybody an idea how I can achieve this?
答
listA.retainAll(listB);
// listA now contains only the elements which are also contained in listB.
如果您想避免 listA 中的更改受到影响，那么您需要创建一个新的.
If you want to avoid that changes are being affected in listA, then you need to create a new one.
List<Integer> common = new ArrayList<Integer>(listA);
common.retainAll(listB);
// common now contains only the elements which are contained in listA and listB.