How to run a java class with a jar in the classpath?

Question

So, I can do this very well:

java mypackage.MyClass

if ./mypackage/MyClass.class exists. I can also happily do this:

java -cp myjar.jar mypackage.MyClass

if the class file exists in the appropriate part of the jar. Easy stuff. But I can't for the life of me manage to do something like this:

java -cp utilities.jar mypackage.MyClass

where ./mypackage/MyClass.class exists, and where ./utilities.jar exists (not containing MyClass, of course).

Am I about to feel stupid?

Answer 1

Possibly :)

# On Unix
java -cp utilities.jar:. mypackage.MyClass

# On Windows
java -cp utilities.jar;. mypackage.MyClass

Basically that's just including . (the current directory) on the classpath as well as the jar file.

Answer 2

Try this if you're on Windows:

java -cp .;utilities.jar mypackage.MyClass

Or this if you're on Linux:

java -cp .:utilities.jar mypackage.MyClass

The current directory is not in the CLASSPATH by default when you specify a value for -cp.

Answer 3

You should include the mypackage.MyClass into the CLASSPATH or the -cp parameter. For example:

java -cp utilities.jar;myjar.jar mypackage.MyClass

The path separator is ; on windows and : on Unix/Linux