How can I return the difference between two lists?

Question

I have two array lists e.g.

List a;
contains : 10/10/2014, 10/11/2016

List b;
contains : 10/10/2016

How can i do

Answer 1

If you only want find missing values in b, you can do:

List toReturn = new ArrayList(a);
toReturn.removeAll(b);

return toReturn;

If you want to find out values which are present in either list you can execute upper code twice. With changed lists.