serialization is a process to store an object in secondary storage device, u know that, in simple term its storing information (structure) of an object (class) with its (class level) variable's value. Primitive data type (int, char,....) are by default eligible for this, and if your (main) object have reference to another (contained) object that object should be serializable, by implementing serializable interface or by other mean. In case object contains reference to another object and that object is not serializable then while deserialization (when you are reading object from secondary storage to memory) that (contained) object included in (main) object will be available but the value of (contained) object will be lost, because it was never stored.
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