You need "equals(Object o)", not "Book book". See Thilo Schwarz's implementation below. And "==" is wrong for Java string comparison. ... <看更多>

Full Java Course: https://course.alexlorenlee.com/courses/learn- java -fastIf you're new to programming, I HIGHLY RECOMMEND solving challenges ... ... <看更多>

should we always override the equals and hashCode even if we don't intent at that point to use the class with any Collection classes? ... <看更多>