uniq

**mac** · 04-06-2010, 06:29 PM

In one word, what's wrong with this method?
Idea is that it should return a list that contains no duplicates

Java Code:

private List<String> uniqueArguments(ArrayList<String> arrayList) {
   List<String> noDups = (List<String>) new HashSet<String>(arrayList);
		return noDups;
}

In anticipation of why i think there is something wrong with it, the following is a warning i get "Type safety: Unchecked cast from HashSet<String> to List<String>"

And also, it does not work :(
Exception in thread "main" java.lang.ClassCastException: java.util.HashSet cannot be cast to java.util.List

Java Code:

private List<String> uniqueArguments(ArrayList<String> arrayList) {
	System.out.println(arrayList);
	HashSet<String> noDups = new HashSet<String>(arrayList);
	System.out.println(noDups);
	return (List<String>) noDups;
}

1 more comment, sysouts work and print what's expected, but still
Exception in thread "main" java.lang.ClassCastException: java.util.HashSet cannot be cast to java.util.List