Package Problem?Pls Help

[Azam Bukhari]

Dear Java Community
If you find my directory structure confusing from the paras below please refer to Dig. below:-
-----------------------------------------------------------------Part-I
-----------------------------------------------------------------I am using Windows 98 & facing problem with Packages or better to say at the time of compilation.,
I have three programs (1) Line.java (2) Point.java and the main() one (3)TryPackage.java stored as follow
C:\MYWORK\Packages\Geometry> contains Line.java & Point.java
C:\MYWORK\Packages\TryPackage> contains TryPackage.java
now when i compile TryPack like this:-
C:\MYWORK\Packages\TryPackage>javac -classpath "C:\MYWORK\Packages" TryPackage.java
it compiles fine but when i try to run the program like this
C:\MYWORK\Packages\TryPackage>java -classpath "C:\MYWORK\Packages" TryPackage
the following error ocurs
Exception in thread "main" java.lang.NoClassDefFoundError: TryPackage
Now how i over come the problem is that cut both my *.java & *.class file from the TryPackage folder delete the folder and paste both the files in the packages folder along with Geometry folder....compile them & run the application again it runs fine.
-----------------------------------------------------------------Part-II
-----------------------------------------------------------------Why do we need to compile our program when workin with package using the classpath stuff, i mean when i tried to compile TryPackage.java like
C:\MYWORK\Packages>javac TryPackage.java
and run it like
C:\MYWORK\Packages>java TryPackage
it works fine then also....so whats the purpose
Please if possible, refer me some easy to understand tutorial or just HELP ME OUT!
Regards
Azam Bukhari
[email protected]
-----------------------------------------------------------------Diagramatic View
-----------------------------------------------------------------
finally my directory structure looks like this @ the time of error free execution:-

C:\>MyWork__
            \____>Packages
                      __/ \___
                  ___/        \__ 
 TryPackage.java /               \__>Geometry
                                                                                                         ___/ \___
                             Line.java /         \ Point.java

[This message has been edited by Cindy Glass (edited December 03, 2001).]

[Jane Griscti]

Hi Azam,
Packages relate to the directory structure. When you are compiling, the JVM will search for the corresponding directory starting from the current directory.
Assuming that:

• Line.java and Point.java both contain the package statement: <code>package Geometry;</code> and have <code>public</code> access
  
• TryPackage.java contains the package statement <code>package TryPackage;</code> and has public access and contains an import statement <code>import Geometry.*;</code>
  

Make sure you are in the directory <code>c:\mywork\packages</code> and compile using the following command:
<code>javac -d . Geometry\*.java</code>
Followed by
<code>javac -d . TryPackage\*.java</code>
The '-d' tells the compiler to place the class files in the the package directory. The '.' tells it to begin its directory search from the current directory.

Hope that helps.
------------------
Jane Griscti
Sun Certified Programmer for the Java� 2 Platform
Co-author Mike Meyers' Java 2 Certification Passport
[This message has been edited by Jane Griscti (edited December 02, 2001).]