SerialVersionUID Guide 📖

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The serialVersionUID is a unique identifier that helps with version control of serialized objects in Java. When
an object is serialized, it generates a unique identifier based on various factors such as class name, interfaces
implemented, methods, etc. This identifier is stored along with the serialized data.

If you change the class definition (e.g., adding or removing fields, methods) and attempt to deserialize an old
version of the serialized object using the new class definition, Java will compare the serialVersionUID of both
versions:

1. Compatibility: If the serialVersionUIDs match, Java assumes that the class definitions are compatible,
   and deserialization proceeds smoothly.
2. Incompatibility: If they don't match, a InvalidClassException is thrown.

By explicitly declaring a serialVersionUID, you ensure consistent behavior across different versions of your
class:

• The same ID guarantees compatibility between old and new serialized data unless significant changes are made to
  the class structure that would require special handling.
• Prevents accidental mismatches if the default generated ID happens to change due to minor modifications.

Let's look at an example to illustrate this:

Suppose you have a class with version 1:

public class Example implements Serializable {
    private static final long serialVersionUID = 1L;
    // fields and methods...
}

Now, if you make a minor update (e.g., adding a comment) without changing the serialVersionUID,
serialization/deserialization will still work as expected:

public class Example implements Serializable {
    private static final long serialVersionUID = 1L;
    // fields and methods...
}

If, however, you add or remove significant parts of the class (e.g., a new field) without updating the
serialVersionUID, deserialization might fail because the default-generated ID has changed:

public class Example implements Serializable {
    private static final long serialVersionUID = 2L; // Changed to indicate incompatible changes
    private int newField;
    // fields and methods...
}

In this case, if you're careful with your serialVersionUID, you can decide whether old serialized objects are
still compatible or should throw an exception.