#Java serialization data version 5 update
#Java serialization data version 5 software

#Java serialization data version 5 software

For a large project with a pool of developers of different skill levels, and (as always) time pressure, there is almost a 100% chance that youвЂ™ll get bugs in production software releases related to serialization. For a small project with a small team of experienced developers, itвЂ™s doable - with sufficient investment in design, reviewing and testing. Making multiple versions of the same class serialization-compatible is really hard work. For the details of how things can go wrong, see below.ДЇor the third and fourth items, I recommend you reconsider your requirements. Best to just avoid this by not defining serialVersionUID explicitly. But in the second, if you ever do get a mismatch of code, then rather than get a deserialization failure you may just get weird behaviour instead, due to Java вЂњforcingвЂќ old data into a new class or vice-versa. Does setting an explicit serialVersionUID do any harm? Well in the first in-memory-only case, no (and actually is slightly more efficient).

So, assuming your use-case is one of the first two above, do NOT explicitly specify serialVersionUID for the class in question. This is common in web-based systems where the web-tier and business-tier are always updated together. If they are passed between a client and server application, but the client and server are always intended to be the same version (ie are released together) then you do not need an explicit serialVersionUID. An example of this kind of usage is a database cache which stores previously-read objects in their serialized form - which can be compressed to save memory. If an object is just serialized into a memory buffer, then you do not need an explicit serialVersionUID - it is absolutely impossible for the writer and reader of the data to be different versions. Java applications may have different versions of the same serializable class.

the object is being passed across the network to another java application which may have a different release-cycle - ie the two communicating.

the object is being saved to disk for later retrieval - possibly by a different version of the application.

the object is being passed across the network to another java application, and the two applications are always released in sync with each other.

the object is just being stored in-memory and will be read back in by the same process that wrote it out.

There are the following different use-cases: Once youвЂ™ve decided to make a class Serializable, the first question you need to ask now is: how will instances of this class be used?

for an application to save an instance to persistent storage, and read it back later.

two applications that each have a copy of the same java class to transfer instances of that class and.

JavaвЂ™s serialization feature is meant to make it easy for: This has to be the most stupid default setting ever hereвЂ™s why. The Eclipse IDE by default displays a warning for any class which implements Serializable but does not define a serialVersionUID field.

#Java serialization data version 5 update

( update regarding synthetic methods, ) Introduction Java Serialization and the serialVersionUID Property First published on: October 22, 2013