how to delete last element in java.util.Set?
You will need to cast back to TreeSet, as Set's don't have any order.
listOfSources.remove( ((TreeSet) listOfSources).last() );
As an alternative you can set listOfSources as a SortedSet
SortedSet<String> listOfSources = new TreeSet<String>();
Then you can use last()
method without casting to TreeSet
listOfSources.remove(listOfSources.last());
I think that this is a preferred approach since you suppose that your Set has an order.
For TreeSet you can use pollLast
function.
listOfSources.pollLast();
See : http://docs.oracle.com/javase/7/docs/api/java/util/TreeSet.html#pollLast()