Key Project

December 1998

Troubleshooting

some hints and tips about how to fix common problems

Key not starting properly

if the socket seems not to initialise (ie, you get 'boot completed', but never '0.0.0.0 2809 initialised' in your startup messages, perhaps your Linux box is trying to lookup DNS for 0.0.0.0. Make sure you have an entry in your hosts for it. For some reason Java assumes that 0.0.0.0 is the localhost.

java.lang.ClassNotFoundException

if you get:

[key.Key]: loading global configuration...
key.UnexpectedResult: java.lang.ClassNotFoundException: key.AliasCollection not found
while loading algorithm for collection ''
        at key.Container.loadFrom(Container.java:492)
        at key.Key.loadObject(Key.java:834)
        at key.Tag.loadFrom(Tag.java:231)
        at key.Key.loadObject(Key.java:834)
        at key.StringKeyCollection.loadFrom(StringKeyCollection.java:201)
        at key.Container.readContents(Container.java:628)
		...

(or something similar), then add the type to the bottom of Type.java

java.io.InvalidClassException

If you get a message like:

java.io.InvalidClassException: key.Atom; Local class not compatible: stream classdesc
serialVersionUID=-345254969110657475 local class serialVersionUID=5859663123945492677
        at java.io.ObjectStreamClass.setClass(ObjectStreamClass.java)
        at java.io.ObjectInputStream.inputClassDescriptor(ObjectInputStream.java)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java)
        at java.io.ObjectInputStream.inputClassDescriptor(ObjectInputStream.java)
        at java.io.ObjectInputStream.inputObject(ObjectInputStream.java)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java)
        at key.Registry.readExternal(Registry.java:101)
        at java.io.ObjectInputStream.inputObject(ObjectInputStream.java)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java)
        at key.Key.loadObject(Key.java:725)
        at key.Main.main(Main.java:61)
[boot]: string -FATAL- java.io.InvalidClassException: key.Atom; Local class not
compatible: stream classdesc serialVersionUID=-345254969110657475 local class
serialVersionUID=5859663123945492677 while loading from file 'database'

When you start the program, it's because a class file has changed, and it's serial version id isn't the same anymore. All you need to do is edit the file and put in the new serial id, recompile, and it will work. In this case, I edit "Atom.java", and at the very top of the class, I add:

private static final long serialVersionUID = -345254969110657475L;

The "L" at the end of the number is very important.

modifying classes with pfiles intact

When you add a field, it's initial value is null - it is never initialised to the defaults supplied with =, regardless of how desirable that would be. In readObject() a hack can be made (if newfield == null, newfield = blah) that would ensure pfiles are still loaded correctly.