Compare objects in LinkedList.contains()

Question

I want to be able to have LinkedList.contains() return true for a custom comparator.

Suppose that I have 1 LinkedList and 2 objects

LinkedList

        

Answer 1

( a == b ) == true

Did you mean a.equals(b) and b.equals(a) return true? This is not the same as a check for reference equality, nor a check for a.compareTo(b) == 0.

LinkedList.contains() uses equals(), so you have to make sure that the method has been implemented correctly. equals() should also be consistent with compareTo(), though this is not strictly necessary. If you're using a hash-based data structure (e.g. HashSet), you must ensure that hashCode() is implemented correctly.