Junilu, Ian, Peter and others pls help

[Amit Kr Kumar]

I am facing a very unusual problem. I have created an executable server jar file. I am able to run it using the java -jar server.jar from the same directory where server.jar file is lying.
However when i go to any other directory from prompt and execute java -jar server.jar it says :

Exception in thread "main" java.util.zip.ZipException: The system cannot find the file specified
at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.<init>(ZipFile.java:110)
at java.util.jar.JarFile.<init>(JarFile.java:115)
at java.util.jar.JarFile.<init>(JarFile.java:57)
I have set the classpath as well in the prompt
using the command
set CLASSPATH=%CLASSPATH%;c:\server\server.jar;
But still not working
Pls Help

[Eduard Jodas]

When using an executable jar the classpath is set inside the manifest file like:
Main-Class: ressa.GestorDatos
Class-Path: ./ lib/common.jar lib/mm.mysql-2.0.11-bin.jar lib/xmlParserAPIs.jar lib/xercesImpl.jar
Remember to press enter at the end of the last line
Note that the classpath is relative to the jar location
This works, at least, in Windows 98

[Amit Kr Kumar]

Thanks Eduard
But for this assignment we dont need to refer to any other jar file in the classpath
Let me explain u using an example:
1) i created a simple test program test.java which has a main method that out puts hello world
This test.java is in package myprogs
2) I create a manifest file for it having value
Main-Class: myprogram.test
3) i made an executable jar file for this as
jar -cfm test.jar mymanifest myprograms\
4) Now i have test.jar file which is excutable.
5) if this file is in c:\amit and i am also in same directory on commnand prompt, i can run java -jar test.jar that works

but when i go to any other folder on the command prompt and run the same command it gives the error java.util.zipexception which means that it is not able to fond the jar file. I setted this file in class path but not working.

Pls Help
test.jar is just an example but same i am doing for running server.jar in this assignment
Amit

[Gurpreet Saini]

Hi Amit,
Suppose you change your directory and place it in d:\sun .Then, Simply give this command:
set classpath=d:\sun
and enter it.
Let me know if it works.

[ July 23, 2002: Message edited by: Gurpreet Saini ]

[Amit Kr Kumar]

Hi Gurpreet
By changing the directory i mean changing the current working directory using cd c:\Program Files and not changing the location of the test.jar file.
The jar file is still in c:\amit
if the current working directory on the command prompt is the same as of the directory in which the test.jar file lying, then it works but if they are not the same then it give this error.
Amit

[Eduard Jodas]

Look at the contents of your jar file using for example:
jar -tf <your-jar-name>
Sample output:
META-INF/
META-INF/MANIFEST.MF
myprogram/test.class

If your test class name and package is not displayed properly that means you haven't created the jar file correctly.
You can try with this command:
jar -cfm test.jar mymanifest -C myprograms\
This should work if myprogam/test.class is inside myprograms folder

[Gurpreet Saini]

Hi,
I got you. What so ever may be the directory whether you are in sub directory or you change the directory. Every time you shift your program from one place to another you are expected to change the classpath that means everytime you have to set the classpath for a reason that you are changing the directories (Whether sub directory or same directory). During run time JVM looks for the all associated files which are to be linked with each other. For this reason it is desirable that you change your classpath.
I dont know which is your platform. So, I cant say which would be actual format of classpath. But if you are using windows then change your classpath w.r.t directory. THIS THING YOU HAVE TO DOCUMENT IN YOUR README.TXT FILE. OTHERWISE PROBLEM !!!

Thank you,

[Amit Kr Kumar]

Thanks Eduard
I have followed all the steps u have written. After creating the jar file i placed in c:\amit
After that
1) i opened a command prompt and executed
cd c:\amit
2) Then i set the classpath as:
set CLASSPATH=%CLASSPATH%;c:\amit\test.jar
3) then i went to folder called nitin
cd c:\nitin
4) i tried
java -jar test.jar
it gave me the follwing error
Exception in thread "main" java.util.zip.ZipException: The system cannot find th
e file specified
at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.<init>(ZipFile.java:110)
at java.util.jar.JarFile.<init>(JarFile.java:115)
at java.util.jar.JarFile.<init>(JarFile.java:57)
Again i changed the current working directory on the command prompt as:
cd c:\amit
and executed java -jar test.jar and it worked
Thus problem is not resolved
REMEMBER : the test.jar file is always in c:\amit
The following lines are taken from javadoc section
**************************************
PS: "When you use -jar option, jar file is the source of all user classes and other classpath settings are ignored".
Found this comment in the java docs..
****************************************
Is this the reason ???
Pls Help
Amit
[ July 24, 2002: Message edited by: Amit Kr Kumar ]

[Eduard Jodas]

I see know! I got confused! Sorry!
The problem is not the classpath. The problem is that Java can't find the jar file. In fact, if all your classes are inside the jar file, then you don't even need a classpath
I'm afraid the only way I know is using the full path like:
java -jar c:\amid\test.jar
If you omit the directory then java looks for the jar file in the current directory.

[Amit Kr Kumar]

Yup u right it works that way
But exam instruction says:
*************************************
How to execute the programs. You must provide exact command-line instructions. If any environmental setup is required, do not just say what needs to be done; provide instructions on how to perform the setup. For example, do not say something like "add server.jar to your classpath". You should document exactly how to add the jar file to the classpath.
Note: your program must run correctly no matter what directory it is installed in.
*****************************************
Read the last line carefully
How to meet this requirement in this case ???
How u started your server and client ??
Amit

[Eduard Jodas]

I don't bother about that. In windows I just have to double click over the application jar file and it works. No need of environment variables like classpath. I'm sure other graphical OS work the same way.
The command lines are very easy:
java -jar <install-dir>/server.jar
java -jar <install-dir>/client.jar
They must provide the installation directory. This way my program works no matter the directory it has been installed in.
However, advice from those who have already uploaded the assignment would be welcomed.