Starting the Instance and Client

Having installed Hazelcast, you can get started.

In this short tutorial, we:

  1. Create a simple Java application using the Hazelcast distributed map and queue.
  2. Run our application twice to have a cluster with two nodes (JVMs).
  3. Connect to our cluster from another Java application by using the Hazelcast Native Java Client API.

Let's begin.

  • The following code starts the first instance (node), and creates and uses the customers map and queue.
import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;

import java.util.Map;
import java.util.Queue;

public class GettingStarted {
  public static void main( String[] args ) {
    HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();
    Map<Integer, String> customers = hazelcastInstance.getMap( "customers" );
    customers.put( 1, "Joe" );
    customers.put( 2, "Ali" );
    customers.put( 3, "Avi" );

    System.out.println( "Customer with key 1: " + customers.get(1) );
    System.out.println( "Map Size:" + customers.size() );

    Queue<String> queueCustomers = hazelcastInstance.getQueue( "customers" );
    queueCustomers.offer( "Tom" );
    queueCustomers.offer( "Mary" );
    queueCustomers.offer( "Jane" );
    System.out.println( "First customer: " + queueCustomers.poll() );
    System.out.println( "Second customer: "+ queueCustomers.peek() );
    System.out.println( "Queue size: " + queueCustomers.size() );
  • Run this GettingStarted class a second time to get the second node started. The nodes form a cluster. You should see something like the following.
Members [2] {
  Member []
  Member [] this
  • Now, add the hazelcast-client-<version>.jar library to your classpath. This is required to use a Hazelcast client.

  • The following code starts a Hazelcast Client, connects to our two node cluster, and prints the size of the customers map.

package com.hazelcast.test;

import com.hazelcast.client.config.ClientConfig;
import com.hazelcast.client.HazelcastClient;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.IMap;

public class GettingStartedClient {
    public static void main( String[] args ) {
        ClientConfig clientConfig = new ClientConfig();
        HazelcastInstance client = HazelcastClient.newHazelcastClient( clientConfig );
        IMap map = client.getMap( "customers" );
        System.out.println( "Map Size:" + map.size() );
  • When you run it, you see the client properly connecting to the cluster and printing the map size as 3.

Hazelcast also offers a tool, Management Center, that enables you to monitor your cluster. To use it, deploy the mancenter-<version>.war included in the ZIP file to your web server. You can use it to monitor your maps, queues, and other distributed data structures and nodes. Please see the Management Center section for usage explanations.

By default, Hazelcast uses Multicast to discover other nodes that can form a cluster. If you are working with other Hazelcast developers on the same network, you may find yourself joining their clusters under the default settings. Hazelcast provides a way to segregate clusters within the same network when using Multicast. Please see the Creating Cluster Groups for more information. Alternatively, if you do not wish to use the default Multicast mechanism, you can provide a fixed list of IP addresses that are allowed to join. Please see the Join Configuration section for more information.


You can also check the video tutorials here.