Why do I get the message: "The serializable class Input Exception does not declare a static final serial Verison UID field of type long"?

Question

I have a public class that extends Exception. It is my custom Exception class that looks like this:

package com.yahoo.chris511026.paragraphcount;

    public class InputException extends Exception {

    public String getMessage() {

        return "Error: No text entered.";

    }

}

Underneath InputException is a yellow line indicating that the class InputException does not declare a static final version UID field of type long. Why is it saying this if my class doesn't implement the Serialiazble interface? What do I do to clear resolve this issue. I don't want to have to modify or add anything to my code.

possible duplicate of [What does it mean: The serializable class does not declare a static final serialVersionUID field?](http://stackoverflow.com/questions/2288937/what-does-it-mean-the-serializable-class-does-not-declare-a-static-final-serial) — T.J. Crowder, Feb 11 '13 at 15:36
Your class *does* implement the Serializable interface, by inheritance. — user207421, Feb 11 '13 at 17:06

Stephen C · Answer 1 · 2013-02-12T01:27:40.647

This is a warning not an error. It is pointing out that it is good practice to add a serialVersionUID field to any serializable class. And your exception class is already serializable because it indirectly extends Throwable and Throwable implements Serializable.

(If you don't define a serialVersionUID field, then the JVM computes one on the fly based on the current API definition of the class. This makes you more vulnerable to problems with serial version UID mismatches due to class changes.)

Why is it saying this if my class doesn't implement the Serialiazble interface?

No. It is not saying that.

What do I do to clear resolve this issue. I don't want to have to modify or add anything to my code.

There are three ways to deal with this:

If you don't want to change any code, modify your IDE's compiler settings to disable this warning.
Add a serialVersionUID field; e.g. using your IDE's accelerator which should offer you the option of computing it using the standard algorithm.
Add an appropriate @SuppressWarning annotation. This would be appropriate if there is zero chance that your exception objects would need to be serialized in the future.

Simon Verhoeven · Answer 2 · 2013-02-11T15:47:55.513

1

You extend Exception which itself extends Throwable which implements Serializable.

Update since a bit too much is ending up in comments:

Options:

add the id
@SuppressWarning("serial")
configure your IDE to ignore it
ignore it alltogether

edited Feb 11 '13 at 15:47

answered Feb 11 '13 at 15:37

Simon Verhoeven

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so is this a natural cosequence or did i make a mistake? – Chris Olszewski Feb 11 '13 at 15:40
how can i circumvent this issue I don't want to extend serializable if I'm not using it. – Chris Olszewski Feb 11 '13 at 15:40
Natural consequence, and since you want to extend Exception you can't really circumvent it. But it is a warning not an error so you can ignore it although I would not recommend it. An interesting read for you: http://java.dzone.com/articles/dont-ignore-serialversionuid – Simon Verhoeven Feb 11 '13 at 15:42
@ChrisOlszewski You have no choice here. But still: it is just a warning, not even an error and you can even configure your IDE to not report it as a warning. – Mark Rotteveel Feb 11 '13 at 15:43
Which IDE? Or just add: @SuppressWarning("serial") – Simon Verhoeven Feb 11 '13 at 15:45
@ChrisOlszewski You can't this is standard in Throwable... when you extend from Exception you get the warning that you need to declare the serial version uid. But why not just declare it – Lyrion Feb 11 '13 at 15:45
•Recommended: add the id Slightly ? – Chris Olszewski Feb 11 '13 at 15:49
what does it mean to add the id Slightly? – Chris Olszewski Feb 11 '13 at 15:50
@Chris my bad. Updated it. And removed personal preference in this case. If you really know what you're doing it doesn't matter all that much which you pick. – Simon Verhoeven Feb 11 '13 at 15:50

score 0 · Answer 3 · answered Feb 11 '13 at 15:38

The Exception class implements the Serializable interface and, through inheritance, so does your class.

The serial version unique id exists so that you can distinguish between versions of the same class when de-serialising it (e.g. if you later want to add a new member to your class that would make it incompatible with older versions without that member).

score 0 · Answer 4 · answered Feb 11 '13 at 15:42

Because the java exception class implements the Serializable interface . And thus you must declare the static final version UID in the child classe of the class exception.

If you don`t declare it, the program will automatically generate one. This is ok for most situation but may cause problem if two exception classes generate the same UID or if the class change and you happen to desirialize an old exception with the old UID.

Why do I get the message: "The serializable class Input Exception does not declare a static final serial Verison UID field of type long"?

4 Answers4