Serialization

All your distributed objects such as your key and value objects, objects you offer into distributed queue and your distributed callable/runnable objects have to be Serializable.

Hazelcast serializes all your objects into an instance of com.hazelcast.nio.serialization.Data. Data is the binary representation of an object.

When Hazelcast serializes an object into Data, it first checks whether the object is an instance of com.hazelcast.nio.serialization.DataSerializable, if not it checks if it is an instance of com.hazelcast.nio.serialization.Portable and serializes it accordingly.

Hazelcast optimizes the serialization for the below types, and the user cannot override this behavior:

• Byte
• Boolean
• Character
• Short
• Integer
• Long
• Float
• Double
• byte[]
• char[]
• short[]
• int[]
• long[]
• float[]
• double[]
• String

Hazelcast also optimizes the following types. However, you can override them by creating a custom serializer and registering it. See Custom Serialization for more information.

• Date
• BigInteger
• BigDecimal
• Class
• Externalizable
• Serializable

Note that, if the object is not an instance of any explicit type, Hazelcast uses Java Serialization for Serializable and Externalizable objects. The default behavior can be changed using a Custom Serialization.