16.8 - Handling Inheritance
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Understanding Inheritance and Serialization
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Today, we'll discuss how inheritance affects serialization in Java. Can anyone tell me what happens if a superclass is non-serializable but the subclass is?
I think the fields from the superclass wouldn't get serialized.
Exactly! If the superclass is not serializable, its fields are not serialized. Remember this interaction with the acronym 'NSF'—'Non-Serializable Fields'. Can anyone provide an example?
Maybe if you have a class called `Person` that has a nationality field and another class `Employee` that extends it?
Great example! Now, if you serialize `Employee`, what about the nationality of `Person`?
It won't be stored, so it would be lost during deserialization.
That's correct! Understanding this can help prevent data loss in application development.
Impacts of Serialization on Object Integrity
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Now, let’s explore the consequences of losing superclass fields. Why is it critical to ensure all classes in the hierarchy are serializable?
It can lead to an incomplete or erroneous object state if fields are lost.
Precisely! We must ensure a uniform approach to serialization. If `Employee` loses the nationality, how might this affect business logic?
It could cause user data issues, especially if nationality affects how an employee is treated in the system!
Excellent point! Keeping an object’s state intact is essential for integrity in systems. Always check for serializability in class hierarchies.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
In handling inheritance during serialization, if the superclass of a serializable class is not serializable, its fields will not be serialized. This leads to loss of state for those fields upon deserialization, which can significantly impact object integrity.
Detailed
Handling Inheritance in Serialization
Manipulating serialization in Java has specific rules when dealing with inheritance. If a class (subclass) implements the Serializable interface but its superclass does not, the fields defined in the superclass will not be part of the serialization process. This means that upon deserialization, these fields will not maintain their previous states, as they were never written to the byte stream.
Example:
Suppose we have a class Person that is not serializable, containing a field for nationality, and another class Employee that extends Person and is serializable. When we serialize an instance of Employee, the nationality field from Person is ignored and lost. It is critical for developers to ensure that any superclass of a serializable class must also implement Serializable to retain the full object state during serialization processes.
In conclusion, managing inheritance in serialization is an essential aspect of designing robust Java applications, especially when object state consistency is crucial in distributed systems.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Impact of Non-Serializable Superclass
Chapter 1 of 2
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
If a superclass is not serializable, its fields will not be serialized.
Detailed Explanation
When you create a class in Java, it can extend another class (a superclass). If the superclass does not implement the Serializable interface, any fields (variables) defined in that superclass will not be included when an object of the subclass is serialized. This means that when you convert the subclass object into a byte stream and later reconstruct it (deserialize), those fields from the superclass are essentially lost.
Examples & Analogies
Think of a vehicle that has a mandatory inspection before it's allowed on the road. If the vehicle is not inspected, it cannot be registered, and all the features like the engine and wheels can't be considered valid. Similarly, if a superclass isn’t marked as serializable, its properties just won’t be part of the serialization process.
Example of Serialization with Non-Serializable Superclass
Chapter 2 of 2
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Example:
class Person {
String nationality = "Indian";
}
class Employee extends Person implements Serializable {
int id;
}
• On deserialization, nationality will not retain its state.
Detailed Explanation
In the example, the Person class represents a general entity with a nationality. It does not implement the Serializable interface, so when you create an Employee object that extends Person, even though Employee is serializable, the nationality field from Person will not be serialized. When you deserialize an Employee, the nationality field will not have the value "Indian" anymore; it will simply be null or the default value for that field type.
Examples & Analogies
Imagine an employee who comes from a country (like nationality), but when you move their records to a new system (deserialization), you only get their employee ID without any information about their nationality since that part was never recorded. It’s like giving someone a suitcase but forgetting to pack their important travel documents inside.
Key Concepts
-
Inheritance: A relationship where one class derives from another, potentially losing superclass fields during serialization if the superclass isn't serializable.
-
Serialization: The process of converting an object into a format that can be easily stored or transmitted.
Examples & Applications
An Employee class extending a Person class that is not serializable leads to missing the nationality attribute during serialization.
When deserializing an Employee object, the nationality will be null if the superclass is not serializable.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
If parent’s not saved, its fields, they won’t be, resulting in data you’ll never see.
Stories
Imagine a family heirloom guarded by a strict grandparent. If the grandparent is not trusted (non-serializable), the valuable heirloom (the data) won't be passed down. Thus, the family legacy is lost.
Memory Tools
Think of NSF—'Non-Serializable Fields' to remember that these fields fail to serialize.
Acronyms
Use SIKS—'Serializable Inherited Key States' to recall that all class states must be serializable.
Flash Cards
Glossary
- Inheritance
A mechanism in object-oriented programming where a new class derives properties and behaviors from an existing class.
- Serialization
The process of converting an object into a byte stream for storage or transmission.
- Deserialization
The reverse process of serialization, where a byte stream is converted back into an object.
Reference links
Supplementary resources to enhance your learning experience.