import java.util.concurrent.ConcurrentHashMap; public class ConcurrentContainerExample { public static void main(String[] args) { ConcurrentHashMap<String, Integer> concurrentMap = new ConcurrentHashMap<>(); concurrentMap.put("A", 1); concurrentMap.put("B", 2); concurrentMap.put("C", 3); System.out.println("ConcurrentHashMap before modification: " + concurrentMap); concurrentMap.computeIfPresent("A", (key, value) -> value + 1); concurrentMap.computeIfAbsent("D", key -> 4); System.out.println("ConcurrentHashMap after modification: " + concurrentMap); } }