equals()和hashCode()方法被隐式调用时的约定

Question

网上看到那么一个问题，百度了一下没有找到合适的答案。。。求大神解释下。。。

Answer 1

JDK源码的注释说明的很清楚，如果重写了equal方法，也应该重写hashCode方法。看看源码注释吧，是非常好的文档资料呢。
*Note that it is generally necessary to override the hashCode
* method whenever this method is overridden, so as to maintain the
* general contract for the hashCode method, which states
* that equal objects must have equal hash codes.