Question

HI guys,

There is an abc.jar under /tomcat_lib. I need use this in my def.java

I tired

javac -classpath /tomcat_lib/ -d
../classes def.java

but it doesn’t work

But if it works if I use

javac -classpath /tomcat_lib/abc.jar
-d ….

Can anyone help explain it?

Answer 1

To add a jar to your classpath, you need to specify the path up to and including the .jar file.

Quoting the official Java SE 6 documentation at Oracle.com:

Each [item in your classpath] should
end with a filename or directory
depending on what you are setting the
class path to:

• For a .jar or .zip file
  that contains .class files, the class
  path ends with the name of the .zip or
  .jar file.
• For .class files in an
  unnamed package, the class path ends
  with the directory that contains the
  .class files.
• For .class files in a
  named package, the class path ends
  with the directory that contains the
  “root” package (the first package in
  the full package name).

…and from the “Folders and Archive Files” section of the same documentation:

When classes are stored in a directory
(folder), like
c:\java\MyClasses\utility\myapp, then
the class path entry points to the
directory that contains the first
element of the package name. (in this
case, C:\java\MyClasses, since the
package name is utility.myapp.)

But when classes are stored in an
archive file (a .zip or .jar file) the
class path entry is the path to and
including the .zip or .jar file.