The static methods of Hazelcast class reaching hazelcast data components have been removed. The functionality of these methods can be reached from HazelcastInstance interface. Namely you should replace following:

Map<Integer, String> mapCustomers = Hazelcast.getMap("customers");

with

HazelcastInstance instance = Hazelcast.newHazelcastInstance(cfg);
// or if you already started an instance
// HazelcastInstance instance = Hazelcast.getHazelcastInstanceByName("instance1");
Map<Integer, String> mapCustomers = instance.getMap("customers");

With 3.0 there will be no member type as lite member. As 3.0 clients are smart client that they know in which node the data is located, you can replace your lite members with native clients.

Before 3.0 there was a confusion for the term "instance". It was used for both the cluster members and the distributed objects (map, queue, topic etc. instances). Starting 3.0, the term instance will be only used for hazelcast instances, namely cluster members. We will use the term "distributed object" for map, queue etc. instances. So you should replace the related methods with the new renamed ones: As 3.0 clients are smart client that they know in which node the data is located, you can replace your lite members with native clients.

public static void main(String[] args) throws InterruptedException {
    Config cfg = new Config();
    HazelcastInstance hz = Hazelcast.newHazelcastInstance(cfg);
    IMap map = hz.getMap("test");
    Collection<Instance> instances = hz.getInstances();
    for (Instance instance : instances) {
        if(instance.getInstanceType() == Instance.InstanceType.MAP) {
        System.out.println("there is a map with name:"+instance.getId());
        }
    }
}
    

with

public static void main(String[] args) throws InterruptedException {
    Config cfg = new Config();
    HazelcastInstance hz = Hazelcast.newHazelcastInstance(cfg);
    IMap map = hz.getMap("test");
    Collection<DistributedObject> distributedObjects = hz.getDistributedObjects();
        for (DistributedObject distributedObject : distributedObjects) {
            if(distributedObject instanceof IMap)
            System.out.println("there is a map with name:"+distributedObject.getName());
        }
}
                            

PartitionService has been moved to package "com.hazelcast.core" from "com.hazelcast.partition"

Before 3.0, you can removeListener methods was taking the Listener object as parameter. But it causes confusion as same listener object may be used as parameter for different listener registrations. So we have changed the listener API. Anymore, addListener methods return you an unique id and you can remove listener by using this id. So you should do following replacement if needed:

IMap map = instance.getMap("map");
map.addEntryListener(listener,true);
map.removeEntryListener(listener);
    

with

IMap map = instance.getMap("map");
String listenerId = map.addEntryListener(listener, true);
map.removeEntryListener(listenerId);
    

There is no change on IQueue API but there are changes on how IQueue is configured. With Hazelcast 3.0 there will not be backing map configuration for queue. Settings like backup count will be directly configured on queue config. For queue configuration details, see Distributed Queue page.

In Hazelcast 3.0, transaction API is completely different. See transactions part for the new API: Distributed Transactions

Classes MultiTask and DistributedTask have been removed. All the functionality is supported by the newly presented interface IExecutorService. See distributed execution part for detailed usage example: Distributed Execution