Hello! I have two lists and I want to use the methods ListUtils.retainAll and ListUtils.removeAll on them. However, I want to do this several times with comparison methods that are different from the defaul equals-method. I.e I would like to compare the elements in the two lists from several different prespectives.
Consider a class Person that has the attributes firstName and lastName. I could define the equals method to say that two persons equals if they have the same first name. I could also say that they equals if they have the same full name. But what if I want to alternate? So basically what I want to do is this: List<Person> firstList; List<Person> secondList; List<Person> firstNamesThatOccurInBothLists = ListUtils.retainAll(firstList, secondList, [Third equals-comparator argument]); List<Person> fullNamesThatOccurInBothLists = ListUtils.retainAll(firstList, secondList, [Third equals-comparator argument]); Can something of this effect be done with commons collections in any way? /Ludwig
