Java -D does not work, why?

[Dave Elwood]

A few days ago when trying to get a glassfish database to run It told me to run :

java -Dij.something.something=somesuch

before starting ij.bat

okay, that worked.

Now I wish to set the system property derby.system.home, so in a batch file I write

java -Dderby.system.home=C:\derby

and java spills out the help screen contents

-- Sorry, that command needs to be followed by a class to execute

[Jesper de Jong]

The -D option sets a Java system property, but only for the JVM instance that you're running at that time. It does not save the value somewhere. A line like this is incomplete:

java -Dderby.system.home=C:\derby

It's missing the name of the class that you want to run. It should be something like:

java -Dderby.system.home=C:\derby org.mypackage.MyClass

I'm sure that the line you had to enter for Glassfish also had something else after it, otherwise you'd have gotten the same help information from Java.