Map<String,List<String>> capitals = new HashMap(); capitals.put("United States", Arrays.asList("Washington DC")); capitals.put("Canada", Arrays.asList("Ottawa")); capitals.put("South Africa", Arrays.asList("Pretoria", "Cape Down", "Bloemfontein")); for(Map.Entry<String,List<String>> entry: capitals.entrySet()){ if(entry.getValue().size() > 1){ System.out.println(entry.getKey()); } }