Java 为什么需要覆盖Hashmap的hashcode和equals方法？
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Why it is necessary to override hashcode and equals method of key for Hashmap?
提问by Raj
I created a HashMap having Studentas key and String as value.
我创建了一个 HashMapStudent作为键和字符串作为值。
Now everywhere i have read It is necessary to override equalsand hashcodemethod if using as a key for hashmap.
现在我读过的任何地方如果用作哈希图的键，则必须覆盖equals和hashcode方法。
But I did not override it. And insert multiple key value pairs in hashmap. I am also able to fetch it back.
但我没有覆盖它。并在hashmap 中插入多个键值对。我也可以把它取回来。
So why it is necessary?
那么为什么有必要呢？
回答by Prasad Kharkar
They are required when you want to use your objects as useful hashing keys into collections that use hashing.
当您想将对象用作有用的散列键到使用散列的集合中时，它们是必需的。
Have your tried to add the Studentobjects which are meaningfully equal?
First understand the significance of equals method in java
您是否尝试添加Student有意义相等的对象？首先了解java中equals方法的意义
Read the significance of equals and hashcode
