There’s no built in type for ConcurrentHashSet because you can always derive a set from a map. Since there are many types of maps, you use a method to produce a set from a given map (or map class). Prior to Java 8, you produce a concurrent hash set backed by a concurrent hash map, … Read more
map.put(key, map.get(key) + 1); should be fine. It will update the value for the existing mapping. Note that this uses auto-boxing. With the help of map.get(key) we get the value of corresponding key, then you can update with your requirement. Here I am updating to increment value by 1.
If you’re only interested in the keys, you can iterate through the keySet() of the map: Map<String, Object> map = …; for (String key : map.keySet()) { // … } If you only need the values, use values(): for (Object value : map.values()) { // … } Finally, if you want both the key and … Read more