NotSerializableException

NotSerializableException is a runtime exception in Java that occurs when an object is attempted to be serialized, but the object's class or one of its superclasses does not implement the java.io.Serializable interface. Serialization is the process of converting an object's state into a byte stream, which can then be saved to a file or transmitted over a network. Deserialization is the reverse process, where the byte stream is used to reconstruct the object.

For an object to be serializable, its class must explicitly declare that it implements the Serializable interface. This interface is a marker interface, meaning it has no methods to implement. Its presence signifies to the Java runtime that instances of the class are allowed to be serialized. If an object contains references to other objects, those referenced objects must also be serializable for the entire object graph to be serialized successfully.

When an attempt is made to serialize an object that is not serializable, the Java serialization mechanism throws a NotSerializableException. This exception prevents the program from proceeding with the serialization operation. Developers need to ensure that all objects intended for serialization are marked as serializable by implementing the Serializable interface. Alternatively, if an object contains non-serializable fields that should not be part of the serialized state, these fields can be marked with the transient keyword. Transient fields are ignored during the serialization process. Understanding and correctly implementing serialization is crucial for applications that rely on saving object states or inter-process communication.