How to Compare Lists of Objects

Question

Hello All,
I have two lists(self developed; not using Java's inherent list functionality) containing objects of the same class. Now I would like to compare the elements within the lists one on one.
Meaning, I would like to compare the two lists to see whether they contain identical elements or not.
How should I do this.
Please help !!
Thank you.

Answer 1

If there is an implicit order on your objects then
1.) Write a Comparator for your objects
http://java.sun.com/j2se/1.4.2/docs/api/java/util/Comparator.html
2.) Sort both lists
3.) int j = 0;
FOR EACH item IN list1 DO
  WHILE list2.get(j) IS LESS THAN item DO
    ++j;
  OD
  IF item EQUALS list2.get(j) THEN
    PRINT "Found dups " + item + " and " + list2.get(j)
  FI
ODIf there exists no implicit ordering, you can only use the trivial solution:FOR EACH item1 IN list1 DO
  FOR EACH item2 IN list2 DO
    IF item1 EQUALS item2 THEN
      PRINT "Found dups " + item1 + " and " + item2
    FI
  OD
OD(BTW - this is pseudo-code)
... or put you stuff in to Sets and use retainAll ...