Java Utililty Methods Map Add

void addOne(Map map, K key)
Increment a Map of K->Integer for a given key.

if (map != null) {
 if (map.get(key) != null) {
 map.put(key, map.get(key) + 1);
 } else {
 map.put(key, 1l);

void addOne(Map map, T key)
given a map of ?

Integer count = map.get(key);
if (count == null)
 count = 0;
map.put(key, count + 1);

Map> addTo(Map> map, K key, T value)
Add a value to a map containing a list of values mapped to a key.

List<T> tl = map.get(key);
tl.add(value);
map.put(key, tl);
return map;

void addTo(Map map, N key, E element, Class collectionClass)
Adds element to the value-collection of key in map.

C collection = map.get(key);
if (collection == null) {
 try {
 collection = (C) collectionClass.newInstance();
 } catch (Exception e) {
 e.printStackTrace();
 map.put(key, collection);
...

T addToAnd(T target, Map... items)
add To And

for (Map item : items)
 ((List) target.get("$and")).add(item);
return target;

List addToList(Map> map, X key, Y value)
add To List

List<Y> values;
if (map.containsKey(key)) {
 values = map.get(key);
 values.add(value);
} else {
 values = new ArrayList<Y>();
 values.add(value);
 map.put(key, values);
...

void addToListMap(Map map, Object key, Object value)
Add a value to a Map from keys to Set of values, creating the value list as needed.

if (map == null) {
 throw new IllegalArgumentException("invalid map");
if (key == null) {
 throw new IllegalArgumentException("invalid map key");
List valuesList = (List) map.get(key);
if (valuesList == null) {
...

boolean addToListMap(Map> map, K key, V value)
Populated a (key,value) pair in a map of lists.

if (map == null) {
 return false;
List<V> list = map.get(key);
if (list == null) {
 list = new ArrayList<V>();
 map.put(key, list);
if (!list.contains(value)) {
 list.add(value);
 return true;
return false;

void addToListMap(Map> map, String key, String value)
Adds another element to the Map: The list of strings is enlarged

List<String> currentList;
if (map.containsKey(key)) {
 currentList = map.get(key);
} else {
 currentList = new ArrayList<String>();
currentList.add(value);
map.put(key, currentList);
...

Map> addToListMap(Map> map, T key, T value)
add To List Map

if (map == null)
 return null;
if (key == null || value == null)
 return map;
List<T> set = map.get(key);
if (set == null)
 set = new ArrayList<T>();
set.add(value);
...