Concurrent Collection:

In Java, concurrent collections are created so that multiple threads can safely access and modify them at the same time. To make sure that operations on these collections are performed in a way that reduces data corruption or errors in a multi-threaded environment, they offer thread safety techniques.

Need of Concurrent Collections:

Standard collections are not thread-safe, such as ArrayList and HashMap. Inconsistent states or data corruption can occur from concurrent thread access to and modification of these collections. Concurrent collections provide integrated safety features to make sure that multiple threads can safely manipulate data at the same time. Concurrent access to shared data in a multi-threaded structure might cause unexpected errors due to the conflicts. In order to make sure that operations on shared data execute predictably, concurrent collections are made to keep data consistency and integrity.

Performance can be affected by using traditional synchronization techniques like locks, which can cause conflicts between threads. Concurrent collections reduce contention and increase performance in concurrent collections by utilizing improved data structures and algorithms like lock-striping and non-blocking procedures.

It might be difficult and prone to errors to manually synchronize concurrent collections in order to make them thread safety. Working with shared data across multiple threads is made easier for developers by concurrent collections, which offer a simpler.

ConcurrentHashMap:

Java's java.util.concurrent package has a thread-safe implementation of the Map interface called ConcurrentHashMap. It is specially made to allow many threads to access it simultaneously without any need for external synchronization. Multiple threads can read and write simultaneously using ConcurrentHashMap without the need for external synchronization. It does this by combining techniques, including internal synchronization methods and lock-striping. As a result, the underlying data is divided into "buckets" or "segments." Because each segment is independently locked, there is less overload because multiple threads can work on various segments at once.

Syntax:

ConcurrentHashMap<KeyType, ValueType> c = new ConcurrentHashMap<>();

Operations:

put(K Key, V Value): Places a key-value pair into the map.

remove(Object key): This function removes the map of a key in the mapping.

putIfAbsent(K key, V Value): Inserts a new key-value pair if the key is not present in the map.

Filename: ConcurrentHashMap.java

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.*;

public class ConcurrentHashMapDemo

{

public static void main(String[] args)

{

ConcurrentHashMap<Integer, String> c = new ConcurrentHashMap<>();

c.put(29, "Bob");

c.put(31, "Alice");

c.put(16, "Eve");

c.putIfAbsent(20, "Mallory"); // It is added into the map because 20 is absent

c.remove(29, "Bob"); // removing the key value and its associated value

c.putIfAbsent(20, "Turdy"); // it cannot be added; already key value is present

c.replace(20, "Mallory", "Turdy"); // replacing the string value

System.out.println(c);

}

}

Output:

{16=Eve, 20=Turdy, 31=Alice}

Conclusion:

Java concurrent collections provide thread safety and effective access to the shared data structure, also reducing major issues related to concurrent programming. They meet the various concurrent requirements in contemporary software development by providing a balance between thread safety, overall performance, and scalability. In order to properly utilize their advantages while resolving any possible drawbacks in concurrent programming, it is essential to understand their properties, take into consideration specific scenarios, and analyze decisions.

Need of Concurrent Collections in Java

Concurrent Collection: