ConcurrentMapmap = new ConcurrentHashMap<>(); map.put("key1", 1); map.put("key2", 2); map.put("key3", 3); int size = map.size(); System.out.println(size); //Output: 3
ConcurrentMapIn this example, we create a new ConcurrentHashMap and add three key-value pairs to it. We then use the computeIfAbsent() method to add a new key-value pair to the map only if the key does not already exist. We then retrieve the value associated with the "key4" key and output it to the console. Overall, the ConcurrentMap interface provides a convenient way to handle thread-safe maps in Java, and its methods can be useful in concurrent programming.map = new ConcurrentHashMap<>(); map.put("key1", "value1"); map.put("key2", "value2"); map.put("key3", "value3"); map.computeIfAbsent("key4", key -> "value4"); String value4 = map.get("key4"); System.out.println(value4); //Output: value4