ConcurrentHashMapscores = new ConcurrentHashMap<>();
ConcurrentHashMapscores = new ConcurrentHashMap<>(); scores.putIfAbsent("John", 10);
ConcurrentHashMapThis operation replaces the value of the key "John" with 20. In conclusion, ConcurrentHashMap is a useful class that provides thread-safe operations on a hash table. Its package library is java.util.concurrent.scores = new ConcurrentHashMap<>(); scores.put("John", 10); scores.replace("John", 20);