serialversionuid

I want Eclipse to generate a serialVersionUID for classes that implement Serializable . However, my Eclipse instance does not throw me a warning or an error when I create a class that implements Serializable . Also, it does not give an suggestion about adding a generated serialVersionUID . Where do I change the required setting? To turn on warning for Serializable class without a serialVersionID, go to Window > Preference > Java > Compiler > Errors/Warnings and search for Serializable class without a serialVersionID . Set that to Error or Warning based on your preference. Once warning for "

A few months back I serialized a java.io.Serializable object into a file. Now I need to read the contents, but since then the serialVersionUID has changed, and now I'm getting a "class incompatible" error. I know for a fact that none of the data members have changed, so the only barrier is the serialVersionUID check. Is there a way to either disable the check or to modify the serialVersionUID in the binary file? CLARIFICATION This question is assuming that I can't edit the source. Is there a way I can hack the .class file or perhaps hack the serialized object file (use a hex editor and change

Although I'm not currently planning to serialize anything, I give all serializable outer classes, as well as static nested classes a SerialVersionUID , because that is the proper way to do it. However, I've read here that Serialization of inner classes (i.e., nested classes that are not static member classes), including local and anonymous classes, is strongly discouraged for several reasons. ... So my question is: Should I give inner and anonymous classes a SerialVersionUID each, or should I add a @SuppressWarnings("serial") to those? Is one way more proper than the other? I will in any case

Eclipse nicely generates the serialVersionUID for me. But this seems to be passive code generation as the id won't be automatically updated as I change the file unless I do the generation again. Is there some way to have the serialVersionUID being generated every time I change the contents? The "Save Actions" don't seem to include such an option - has somebody found some way to do this? It would be nice that it could be combined with the IDE save actions or something similar so that I could revert the change if I were doing that doesn't affect the serialization. Best regards, Touko EDIT:

When you extend a class with class Exception ( for creating new exception) you get a warning to have a serialVersionUID . I know that serialVersionUID plays an important role while serialization and deserialization, but when my Exception needs to be serialized? Can anyone give me a practical case in which I want my custom-exception class to have serialization and deserialization? This is because the root class for all exceptions, Throwable implements the Serializable interface. All exceptions by default are serializable and that's a language design decision because the authors wanted

Is there a way to determine the generated serialVersionUID of a serialized Java object? The problem is that I serialized an object without explicitely specifying the serialVersionUID . Now the deserialization process complains about class incompatibilities. However I didn't change the class in a way which would make it incompatible. So I assume that it is enough to specify the serialVersionUID in the class as it is stored in the object data. In order to do this I need to read the serialVersionUID from the serialized data. You can do this by extending ObjectInputStream : public class PrintUIDs

I want to create a class that, for example, extends HttpServlet? My compiler warns me that my class should have a serialVersionUID. If I know that this object will never be serialized, should I define it or add an annotation to suppress those warnings? What would you do and why? I don't know Java best practices, but it occurs to me that if you are claiming that serialization will never happen, you could add a writeObject method which throws. Then suppress the warning, safe in the knowledge that it cannot possibly apply to you. Otherwise someone might in future serialize your object through the