問題描述
你知道嗎:
會輸出:
這是因?yàn)?AbstractCollection
(HashMap$Values
繼承自)沒有覆蓋 #equals()
.p>
你知道為什么會這樣嗎?
根據(jù)Collection#equals()
,Collection 沒有通用的 equals() 方法
,因此 AbstractCollection
無法提供.
請注意,HashMap$Values
既不是 Set 也不是 List,因此很困惑,從某種意義上說,它不支持 equals()
.
Did you know that :
would output :
This is caused by the fact that AbstractCollection
(which HashMap$Values
inherits from) does not overrides #equals()
.
Do you have an idea why this is so ?
Per the contract of Collection#equals()
, there is no general-purpose equals() methods for Collection
s, and thus AbstractCollection
cannot provide one.
Note that HashMap$Values
is neither a Set nor a List, thus the quandary and in a sense the reason it does not support equals()
.
這篇關(guān)于為什么 AbstractCollection 不實(shí)現(xiàn) equals()?的文章就介紹到這了,希望我們推薦的答案對大家有所幫助,也希望大家多多支持html5模板網(wǎng)!