JDate and GDate

[Ian Lubelsky]

I am currently working on the assignment DaysOld.
I wanted to make sure I had the jr.jar properly set up and wrote the following to test it:

import com.javaranch.common.*;

public class DateTest
{
    public static void main(String args[])
    {
        int year = 2010;
        int month = 4;
        int day = 27;
        JDate toto = new JDate(year, month, day);
        GDate tata = new GDate(year, month, day);
        System.out.println(toto);
        System.out.println(tata);
    }
}

It compiles without any problem (javac -cp "C:\Program Files\Java\jr.jar" DateTest.java). The problem arises when I try to run it, I get the following error:

d:\JavaWorkspace\Test_Dir>java DateTest
Exception in thread "main" java.lang.NoClassDefFoundError: com/javaranch/common/JDate
        at DateTest.main(DateTest.java:10)
Caused by: java.lang.ClassNotFoundException: com.javaranch.common.JDate
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 1 more

Is there something I am doing wrong or do I have the jr.jar file not properly setup?

Thanks

[Gary Ba]

The code itself looks good. My thought is the jar file was not integrated correctly. You might want to try it again.

this or this might help.

Good luck,
Gary

[Ian Lubelsky]

Thanks Gary; but the fault was mine why it wasn't working.
I went back to double check to see if I had properly set the CLASSPATH, when I saw that I had actually set it in the Path by mistake. Fixed that and abredacabra it worked.

[Gary Ba]

Good job.

Now the interesting question is why did it compile?
Because if you are using a collection and you forget to import it, it won't compile at all. What is the difference?

I'll wait until one of the smarter folks answer to this thread.

[Ian Lubelsky]

My thinking why it compiled was because it was able to find the jar file in the path, but when I tried to run the script, it was looking in the CLASSPATH and couldn't find anything and gave the error message. Of course I may be wrong, but then again I may be right. I think I just quoted a a Billy Joel song.

[Mike Simmons]

It compiled because you told the compiler where the jar was, using the -cp option:

    javac -cp "C:\Program Files\Java\jr.jar" DateTest.java

When you specify the -cp option (or -classpath option, same thing) it ignores your CLASSPATH system property entirely, and just uses whatever path you gave after the -cp.

You can also use a -cp option when you run the program:

    java -cp ".;C:\Program Files\Java\jr.jar" DateTest

When you do this, again, it will ignore your CLASSPATH system property, and just use the path you give it. Note that I added ".;" at the beginning, so that it also finds the current directory. That's usually a good idea.

[Gary Ba]

Now it makes sense.
Thanks Mike!

[Ian Lubelsky]

Thanks for the info Mike.