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- Because inner classes declared in non-static contexts contain implicit non-transient references to enclosing class instances, serializing such an inner class instance will result results in serialization of its associated outer class instance as well.
- Synthetic fields generated by javac (or other JavaTM Java^superscript^TM compilers) to implement inner classes are implementation dependent and may vary between compilers; differences in such fields can disrupt compatibility as well as result in conflicting default serialVersionUID values. The names assigned to local and anonymous inner classes are also implementation dependent and may differ between compilers.
- Since Because inner classes cannot declare static members other than compile-time constant fields, they cannot use the serialPersistentFields mechanism to designate serializable fields.
- Finally, because inner classes associated with outer instances do not have zero-argument constructors (constructors of such inner classes implicitly accept the enclosing instance as a prepended parameter), they cannot implement Externalizable.
None of the these issues listed above, however, apply to static member classes.
Noncompliant Code Example
In this non compliant noncompliant code example, the fields contained within the outer class are also serialized when the inner class is serialized.
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