问题描述
考虑以下SSCCE：
public static void main(String[] args) {
LinkedHashSet<String> set1 = new LinkedHashSet<>();
set1.add("Bob");
set1.add("Tom");
set1.add("Sam");
LinkedHashSet<String> set2 = new LinkedHashSet<>();
set2.add("Sam");
set2.add("Bob");
set2.add("Tom");
System.out.println(set1);
System.out.println(set2);
System.out.println(set1.equals(set2));
}
打印：
[Bob, Tom, Sam]
[Sam, Bob, Tom]
true
但是如果你将 LinkedHashSet 更改为 LinkedList ：
public static void main(String[] args) {
LinkedList<String> set1 = new LinkedList<>();
set1.add("Bob");
set1.add("Tom");
set1.add("Sam");
LinkedList<String> set2 = new LinkedList<>();
set2.add("Sam");
set2.add("Bob");
set2.add("Tom");
System.out.println(set1);
System.out.println(set2);
System.out.println(set1.equals(set2));
}
它产生：
[Bob, Tom, Sam]
[Sam, Bob, Tom]
false
我的问题是澄清。有人可以帮助理解这个吗？为什么 LinkedHashSet 被视为等于，而相同的 LinkedList 不会？我假设 List 的定义和 Set 扮演一个角色，但我不确定。
My question is one of clarification. Can someone help make sense of this? Why would a LinkedHashSet be considered equals whereas the same LinkedList would not? I'm assuming the definition of List and Set plays a role, but I'm not sure.
基本上，我说如果你认为 Set 是相同的，你不会考虑列表 s也一样吗？反之亦然（假设没有重复的元素）？
Basically, I'm saying if you consider the Sets to be the same, wouldn't you consider the Lists to be the same too? And vice-versa (assuming no duplicate elements)?
推荐答案
保证 LinkedHashSet make是关于迭代顺序的。但是，它仍然是 Set ，而且一套不关心订单本身。另一方面，列表。一个元素位于第三位的 List 与另一个 List 不同，第一个位置的元素相同。
The guarantee that LinkedHashSet makes is about iteration order. However, it's still a Set and a set doesn't care about order in itself. A List on the other hand, does. A List with an element in 3rd position is not the same as another List with the same element in the 1st position.
为方法
Set javadoc for the equals(Object) method
LinkedHashSet javadoc状态
The LinkedHashSet javadoc states
A LinkedHashSet 是一个集。它有相同的规则，即。适用于ADT的那些。
A LinkedHashSet is a Set. It has the same rules, ie. those that apply to the set ADT.
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