Set
Hazelcast Set is distributed and concurrent implementation of java.util.Set.
- Hazelcast Set does not allow duplicate elements.
- Hazelcast Set does not preserve the order of elements.
- Hazelcast Set is non-partitioned data structure where values and each backup is represented by its own single partition.
- Hazelcast Set cannot be scaled beyond the capacity of a single machine.
- Equals method implementation of Hazelcast Set uses serialized byte version of objects compared to
java.util.HashSet.
Sample Set Code
import com.hazelcast.core.Hazelcast;
import java.util.Set;
import java.util.Iterator;
import com.hazelcast.config.Config;
Config cfg = new Config();
HazelcastInstance hz = Hazelcast.newHazelcastInstance(cfg);
java.util.Set set = hz.getSet("IBM-Quote-History");
set.add(new Price(10, time1));
set.add(new Price(11, time2));
set.add(new Price(12, time3));
set.add(new Price(11, time4));
//....
Iterator it = set.iterator();
while (it.hasNext()) {
Price price = (Price) it.next();
//analyze
}
Event Registration and Configuration
Hazelcast Set uses ItemListener to listen to events which occur when items are added and removed.
import java.util.Queue;
import java.util.Map;
import java.util.Set;
import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.ItemListener;
import com.hazelcast.core.EntryListener;
import com.hazelcast.core.EntryEvent;
import com.hazelcast.config.Config;
public class Sample implements ItemListener{
public static void main(String[] args) {
Sample sample = new Sample();
Config cfg = new Config();
HazelcastInstance hz = Hazelcast.newHazelcastInstance(cfg);
ISet set = hz.getSet ("default");
set.addItemListener (sample, true);
Price price = new Price(10, time1)
set.add(price);
set.remove(price);
}
public void itemAdded(Object item) {
System.out.println("Item added = " + item);
}
public void itemRemoved(Object item) {
System.out.println("Item removed = " + item);
}
}
Please refer to Listener Configurations.