使用集合删除重复列表 [英] Using collection to remove duplicate Lists

问题描述

我有 3 个列表，其中两个是重复的.我想将这些列表存储到一个单元中，删除所有重复项，所以我想将每个列表添加到一个集合中.这是我试过的:

I have 3 Lists, two of which are duplicates. I want to store these Lists into one unit, removing all the duplicates, so I was thinking to add each List to a collection. This is what I tried:

List<Integer> coins1 = Arrays.asList(5, 5, 10);
List<Integer> coins2 = Arrays.asList(5, 10, 5);
List<Integer> coins3 = Arrays.asList(10, 10);

coins1.sort((a, b) -> a.compareTo(b));
coins2.sort((a, b) -> a.compareTo(b));
coins3.sort((a, b) -> a.compareTo(b));

Collection<List<Integer>> allCoinPossibilities = new TreeSet();

allCoinPossibilities.add(coins1);
allCoinPossibilities.add(coins2);
allCoinPossibilities.add(coins3);

我收到错误java.util.Arrays$ArrayList 无法转换为 java.lang.Comparable".错误是有道理的，集合不知道如何比较每个列表以禁止重复.我需要覆盖比较方法吗?如果是这样，我该怎么做?这是解决这个问题的正确方法吗?

I get an error "java.util.Arrays$ArrayList cannot be cast to java.lang.Comparable". The error makes sense, the Collection doesn't know how to compare each list to disallow duplicates. Do I need to override a compare method? If so, How would I do that? Is this the correct approach to solving this problem?

谢谢！

推荐答案

制作一个 HashSet 并将所有内容添加到其中.

Make a HashSet and add everything into that.

最后你将只剩下独特的元素

At the end you'll be left with just the unique elements

List<Integer> coins1 = Arrays.asList(5, 5, 10);
List<Integer> coins2 = Arrays.asList(5, 10, 5);
List<Integer> coins3 = Arrays.asList(10, 10);

Set<Integer> dedupedCollection = new HashSet<Integer>();

dedupedCollection.add(coins1);
dedupedCollection.add(coins2);
dedupedCollection.add(coins3);

return dedupedCollection;

然后你可以返回dedupedCollection;作为没有重复的最终集合.

then you can return dedupedCollection; as the final set with no duplicartes.

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