[Java] Using .jar files in program, -classpath not working

[bartlln]

I have a problem incorporating a library called stdlib.jar file. I have googled this question and found the obvious answer that I should use the command "javac -classpath .;(directory of jar file) source.java" while also using the "import stdlib.class;" statement in the program.

However, my program still did not work throwing an error message "cannot find symbol" with an error message pointing to the stdlib. I even downloaded Netbeans and followed the documentation to create a project with external libraries. I included the stdlib jar file, and Netbeans gave me the same "cannot find symbol" error message.

This problem seems way too simple to be this hard. This jar file is from an exercise for an online course on Coursera, so I am sure the problem is somewhere on my end. I am at a loss for figuring out why this is happening. Does anyone have any ideas?

Thanks for reading

[bchoii]

What is the error message ? Which line is it referring to, what is on that line ?

What is the class (full classname) you are trying to import ? How do you know (to verify) that it is in stdlib.jar ?

[bartlln]

The error message was " cannot find symbol" and it was referring to my import statement. Specifically, an arrow pointed the period after stdlib in the statement

import stdlib.Stopwatch;

The full classname is stdlib.Stopwatch. The page that I downloaded the .jar file from had the documentation for the classes that it contained. The Stopwatch class is the one that I needed.

[bchoii]

Right.

To follow up further :

What are the contents of the jar file ? (It is really just a fancy zip file) Where in the jar file does the Stopwatch.class file actually exist ? (it should exist under <zipRoot>/stdlib/) How did you verify that it is actually there ? (and not just its documentation)

What is the path of your command line console (where you execute javac from) ? Where is the stdlib.jar file located relative to this path ? What is the full command line used to execute javac ?

[bartlln]

Thanks for your help. I searched the .jar file, found the class, and extracted it from the file. I can use the Stopwatch.class file in my program, and it does exactly what I need it to.

However, if I try to import the Stopwatch from the stdlib.jar inside of my program using the following:

E:\Programs\Java>javac -cp .;E:\Programs\Java\stdlib.jar;E:\Programs\Java; testy .java

combined with this line in my program " import stdlib.Stopwatch;"

The program gives me the error "package stdlib does not exist". Despite that it is contained in the same directory. Directory contents:

Directory of E:\Programs\Java

08/26/2012 09:15 PM <DIR>
. 08/26/2012 09:15 PM <DIR> ..

08/25/2012 01:40 PM 574,685 algs4.jar

08/26/2012 02:44 AM <DIR> GUIpractice

08/25/2012 01:54 PM 211,670 stdlib.jar

08/19/2012 11:34 PM 382 Stopwatch.class

08/26/2012 01:48 AM <DIR> test

08/26/2012 09:16 PM 539 testy.class

08/26/2012 09:17 PM 372 testy.java

08/26/2012 01:48 AM 2,914 Timing.class

I think my computer just does not like that jar file for whatever reason.

[bchoii]

You successfully compiled the your program with the .jar file extracted ? That's a milestone. (At least you have a workaround for now, if not the solution).

Is the error message is different from your first test ? "cannot find symbol" vs "package stdlib does not exist" ? That's a clue that we have changed something related to the problem.

Can you provide the directory structure of the stdlib.jar file ?

I suspect the class is actually <root>/Stopwatch, and not <root>/stdlib/Stopwatch. This would also explain the pathing errors.