Using Hazelcast distributed sets in Java applications

21 Sep 2023

Hazelcast is an open-source, distributed in-memory data grid solution that provides highly scalable and fault-tolerant data structures. One of these powerful data structures is the Distributed Set which allows you to store a collection of unique elements across multiple nodes in a cluster. In this blog post, we will explore how to use Hazelcast distributed sets in Java applications.

Setting up Hazelcast

To get started with Hazelcast, you will need to add the Hazelcast dependency to your Java project. You can do this by either manually downloading the Hazelcast JAR file and adding it to your project’s classpath or by using a build tool like Maven or Gradle to manage the dependency.

Maven Dependency

<dependency>
  <groupId>com.hazelcast</groupId>
  <artifactId>hazelcast</artifactId>
  <version>4.5</version>
</dependency>

Gradle Dependency

implementation 'com.hazelcast:hazelcast:4.5'

Creating a Distributed Set

Once you have added the Hazelcast dependency to your project, you can create a Hazelcast instance and a distributed set as follows:

import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.ISet;

public class DistributedSetExample {

    public static void main(String[] args) {
        // Create a Hazelcast instance
        HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();

        // Create a distributed set
        ISet<String> distributedSet = hazelcastInstance.getSet("my-distributed-set");
    }
}

In the code snippet above, we first create a Hazelcast instance using the Hazelcast.newHazelcastInstance() method. This will create a new instance of Hazelcast using the default configuration.

We then obtain a reference to a distributed set by calling the getSet() method on the Hazelcast instance. We pass a unique identifier string (“my-distributed-set”) to identify our set.

Performing Operations on Distributed Set

The distributed set provides a rich set of operations that enable you to manipulate the set in a distributed manner. Some of the commonly used operations include:

add(element): Adds an element to the set.
remove(element): Removes an element from the set.
contains(element): Checks if an element exists in the set.
size(): Returns the size of the set.
getAll(): Returns all the elements in the set.

Here’s an example that demonstrates using these operations:

public class DistributedSetExample {

    public static void main(String[] args) {
        HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();
        ISet<String> distributedSet = hazelcastInstance.getSet("my-distributed-set");

        distributedSet.add("element1");
        distributedSet.add("element2");
        distributedSet.add("element3");

        System.out.println("Set size: " + distributedSet.size());  // Output: Set size: 3

        distributedSet.remove("element2");

        System.out.println("Set contains element2: " + distributedSet.contains("element2"));  // Output: Set contains element2: false

        Set<String> allElements = distributedSet.getAll();
        System.out.println("All elements: " + allElements);  // Output: All elements: [element1, element3]
    }
}

Conclusion

Distributed sets in Hazelcast provide a simple and efficient way to store and manipulate a collection of elements across a distributed environment. By following the steps outlined in this blog post, you can easily integrate Hazelcast distributed sets into your Java applications and benefit from their scalability and fault-tolerance. So go ahead, give it a try and unlock the power of Hazelcast distributed sets in your applications!

#Java #DistributedSets #Hazelcast