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Core Java® Volume II—Advanced Features, Ninth Edition by Gary Cornell, Cay S. Horstmann

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1.5.4. Versioning

If you use serialization to save objects, you will need to consider what happens when your program evolves. Can version 1.1 read the old files? Can the users who still use 1.0 read the files that the new version is producing? Clearly, it would be desirable if object files could cope with the evolution of classes.

At first glance, it seems that this would not be possible. When a class definition changes in any way, its SHA fingerprint also changes, and you know that object streams will refuse to read in objects with different fingerprints. However, a class can indicate that it is compatible with an earlier version of itself. To do this, you must first obtain the fingerprint of the earlier version of the class. Use the stand-alone ...

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