Serialization

It’s a mechanism by which you can save or transfer the state of an object by converting it to a byte stream.

It’s required to send the state of an object over a network through a socket.

Serialization in Java

It can be done by implementing Serialiazable interface.

Note: Serialiazable interface is a marker interface.

Serializable vs Externalizable

SerializableExternalizable
Marker interfaceContains methods readExternal() and writeExternal()
Inbuilt serialization mechanismSerialization mechanism can be defined using readExternal() and writeExternal().

Serialization performance optimization

Unwanted or non Serializable attributes should be marked as transient.

Save only the state of the object, not the derived attributes.

Don’t serialize objects with default values.

Serial Version UID

It represents class version. During serialization it is associated with serialized class and thus it is required at the time of deserialization for checking of compatibility. If not declared, Java compiler will make one by creating hash code using most of your class attributes and features.

Transient variables

The transient keyword in Java is used to indicate that a field should not be serialized.

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