What is the purpose of serialization?

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Serialization is the conversion of an object to a series of bytes, so that the object can be easily saved to persistent storage or streamed across a communication link. The byte stream can then be deserialised – converted into a replica of the original object.

In Core Java, serialization refers to the process of converting an object’s state (fields and data) into a byte stream, which can be easily saved to a file or transmitted over a network. The primary purpose of serialization is to enable the persistence of objects, allowing them to be stored and later reconstructed. This is particularly useful in scenarios such as:

  1. Object Persistence: Serialization allows objects to be saved to a file or a database, preserving their state. This is useful for applications that need to store and retrieve complex data structures.
  2. Network Communication: Serialization is essential for sending objects over a network. By converting an object into a byte stream, it can be transmitted to another system where it can be deserialized to reconstruct the original object.
  3. Distributed Systems: In distributed computing environments, objects often need to be passed between different processes or even across different machines. Serialization facilitates this communication by converting objects into a format that can be easily transmitted and reconstructed on the receiving end.

Java provides the Serializable interface, which is a marker interface (an interface with no methods) that classes can implement to indicate that their objects can be serialized. The serialization process in Java is handled by the ObjectOutputStream class for writing objects to a stream and the ObjectInputStream class for reading objects from a stream.

It’s important to note that not all objects are serializable by default. Certain classes may need to implement custom serialization methods (writeObject and readObject) to handle special cases or to exclude specific fields from the serialization process. Additionally, some classes may opt-out of serialization by not implementing the Serializable interface.