List<String> list = new ArrayList(); list.add("Washington"); list.add("Nevada"); list.add("California"); list.add("New York"); list.add("New Jersey"); // <String> long org.apache.commons.collections4.IterableUtils.countMatches(Iterable<String> input, Predicate<? super String> predicate) System.out.println(IterableUtils.countMatches(list, p->((String)p).startsWith("N")));