<dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-collections4</artifactId> <version>4.4</version> </dependency> List<String> myList = new ArrayList<>(); boolean isEmpty = CollectionUtils.isEmpty(myList); List<String> myList = new ArrayList<>(); myList.add("Hello"); boolean isNotEmpty = CollectionUtils.isNotEmpty(myList); List<String> myList = Arrays.asList("Apple", "Banana", "Orange"); boolean containsAny = CollectionUtils.containsAny(myList, "Banana"); Map<String, Integer> myMap = new HashMap<>(); boolean isEmpty = MapUtils.isEmpty(myMap); Map<String, Integer> myMap = new HashMap<>(); myMap.put("Apple", 1); boolean isNotEmpty = MapUtils.isNotEmpty(myMap); Map<String, Integer> myMap = new HashMap<>(); myMap.put("Apple", 1); String key = MapUtils.getKey(myMap, 1);