如何检查两个 ArrayList 是否不同，我不在乎发生了什么变化 [英] How can I check if two ArrayList differ, I don't care what's changed

问题描述

如何检查两个 ArrayList 是否彼此不同?我不在乎有什么不同，我只想知道它们是否相同.

How can I check if two ArrayLists differ from one another? I don't care what's the difference, I just want to know if they're not the same.

我每分钟都从数据库中获取分数列表，并且只有当我获取的分数列表与我一分钟前获取的分数列表不同时，我才会将其发送给客户端.

I'm fetching scores list from a database every minute, and only if the scores list that I fetched is different from the one I fetched a minute ago I want to send it to the client.

现在 ArrayList 的值实际上是我创建的一个类(包含名称、等级、等级、分数).

Now the value of the ArrayList is actually a class that I created (that contains name, lvl, rank, score).

我需要在上面实现 equals() 吗?

Do I need to implement equals() on it?

推荐答案

这里有一个简单的方法来检查 2 个数组列表是否包含相同的值，而不管它们的顺序.

Here's a simple method that checks if 2 Array Lists contain the same values regardless their order.

 //the name of the method explains it well...
    public boolean isTwoArrayListsWithSameValues(ArrayList<Object> list1, ArrayList<Object> list2)
    {
        //null checking
        if(list1==null && list2==null)
            return true;
        if((list1 == null && list2 != null) || (list1 != null && list2 == null))
            return false;

        if(list1.size()!=list2.size())
            return false;
        for(Object itemList1: list1)
        {
            if(!list2.contains(itemList1))
                return false;
        }

        return true;
    }

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