The Distributed Object Listener methods distributedObjectCreated and distributedObjectDestroyed are invoked when a distributed object is created and destroyed throughout the cluster. To write a Distributed Object Listener class, you implement the DistributedObjectListener interface and its methods.

The following is an example Distributed Object Listener class.

public class SampleDistObjListener implements DistributedObjectListener {
  public static void main(String[] args) {
    SampleDistObjListener sample = new SampleDistObjListener();

    Config config = new Config();
    HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance(config);

    Collection<DistributedObject> distributedObjects = hazelcastInstance.getDistributedObjects();
    for (DistributedObject distributedObject : distributedObjects) {
      System.out.println(distributedObject.getName() + "," + distributedObject.getId());

  public void distributedObjectCreated(DistributedObjectEvent event) {
    DistributedObject instance = event.getDistributedObject();
    System.out.println("Created " + instance.getName() + "," + instance.getId());

  public void distributedObjectDestroyed(DistributedObjectEvent event) {
    DistributedObject instance = event.getDistributedObject();
    System.out.println("Destroyed " + instance.getName() + "," + instance.getId());

When a respective event is fired, the distributed object listener outputs the event type, and the name, service (for example, if a Map service provides the distributed object, than it is a Map object), and ID of the object.

Registering Distributed Object Listeners

After you create your class, you can configure your cluster to include distributed object listeners. Below is an example using the method addDistributedObjectListener. You can also see this portion in the above class creation.

HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();
SampleDistObjListener sample = new SampleDistObjListener();

hazelcastInstance.addDistributedObjectListener( sample );

With the above approach, there is the possibility of missing events between the creation of the instance and registering the listener. To overcome this race condition, Hazelcast allows you to register the listeners in the configuration. You can register listeners using declarative, programmatic, or Spring configuration, as shown below.

The following is an example programmatic configuration.

new ListenerConfig( "com.your-package.SampleDistObjListener" ) );

The following is an example of the equivalent declarative configuration.


The following is an example of the equivalent Spring configuration.

   <hz:listener class-name="com.your-package.SampleDistObjListener"/>
   <hz:listener implementation="DistributedObjectListener"/>