Question

I have List<Custom> where Custom is

class Custom {
    public int id;
    public String name;
}

How to get number how many items have different names ? Is there any easier way than put all in set and get set size ?

Answer 1

Put names to set:

Set<String> set = new HashSet<String>();
for (Custom c : list) {
    set.add(c.name);
}
System.out.println(set.size());

You can also fill set with your Custom objects if you use appropriate Comparator that compares names only:

int nDifferentNames = new HashSet<Custom>(list, new Comparator<Custom>() {
    public int compare(Custom one, Custom two) {
        return one.name.compareTo(two.name);
    }
}).size();