I can't figure out to create a .jar file without having a ClassNotFound Exception

[fervent jolt]

I have some code that is finished and I wanted to create an jar file to use it outside IDE and I looked and created an .jar file to execute my code with an MANIFEST.mf file to include the main class but even with this I still get that exception how can I do to make it works? Thanks in advance

[quiet stream]

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[gleaming sequoia]

what is inside of manifest.mf?
how do you run the jar file?

[fervent jolt]

what is inside the manifest file is :

Main-Class: Derivative.class

with an \n at the end

and the command is :

jar -cvfm work.jar MANIFEST.mf C:\Users\HP\Desktop\Programs\Java\Math\Calculus\cal\out\cal\*.class

and for running the jar file I use:

java -jar work.jar

[gleaming sequoia]

no need to have .class in name of the main class

[fervent jolt]

gives me an header error if I don

header field error*

[gleaming sequoia]

maybe you deleted \n?

[fervent jolt]

no

[gleaming sequoia]

manifest usually has ```
Manifest-Version: 1.0
Main-Class: MainClasName

[fervent jolt]

Main-Class: Derivative

[fervent jolt]

it still give me the error

it's suppose to only have .class file right

with the other classes

[gleaming sequoia]

it can contain whatever you want

just there should be thesame structure of the packages (directories) with including class files

andMETA-INF dir for maniifest file

and MANIFEST.MF file in it

[fervent jolt]

so I need to to the command out of the package directory

[gleaming sequoia]

sorry?

[fervent jolt]

so you see in cmd I can be in different directories and since a package is just a folder should I perform the command out of the package directory or inside of it

[gleaming sequoia]

no

java will be looking for the needed class inside of jar as separate classpath

you run the jar file correctly

just make sure that you have right structure

like ```

• Derivative.class
• META-INF
  -- MANIFEST.MF

[fervent jolt]

but command with jar first does I need to have the other class with the main class

[gleaming sequoia]

if main class uses another specific classes (not a part of standard jre set of classes), then yes, it has to be in the jar file as well

Is Derivative class in a package?

[fervent jolt]

yeah in the package cal with Render

[gleaming sequoia]

then you need to set it correctly in manifest file:```
Main-Class: Render.Derivative

java will be looking for the main class starting from the root of jar file

so if main class is in ./Render/Derivative.class, then you set the main class in manifest as I wrote above

[fervent jolt]

no Render is a class

cal is the package

[gleaming sequoia]

ah, so cal.Derivative

[fervent jolt]

I try

but still give me an header field error

jar cvfm MANIFEST.txt Derivative.class Render.class look for yourself

oh

[gleaming sequoia]

manifest.mf, not txt

and, since classes are in packages, you need to add them including packages

[fervent jolt]

jar cvfm work.jar MANIFEST.mf cal.Derivative.class cal.Render.class like this

try this : jar cvfm work.jar cal\MANIFEST.mf cal cal\Derivative.class cal\Render.class

but now there is no manifest attribute

[gleaming sequoia]

best would be using
jar cfe JarExample.jar cal.Derivative cal/*.class

[fervent jolt]

but there is no manifest

[gleaming sequoia]

option e automatically creates it and put as main class the second argument

m if you want to copy existing manifest file

but if only thing you need is to specify the main class, e option is better

since it creates manifest itself, and put as main class the class name, that you specify

[fervent jolt]

but the frame is poping out

[gleaming sequoia]

what frame?

[fervent jolt]

the frame in my program in Render.class

[gleaming sequoia]

and?

[fervent jolt]

even if there is no error if the frame doesnt appear I can't to do anything

with the program

[gleaming sequoia]

at the moment, does jar file work? no errors like main class not found or manifest field error etc?

[fervent jolt]

yeah

[gleaming sequoia]

good, problem is solved, now you know how to create it manually and run it

[fervent jolt]

but the frame

[gleaming sequoia]

now you should show the code

of your classes

[fervent jolt]

import java.lang.Math;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import java.awt.*;
public class Derivative
{
    public static void main(String[] args){
        new Render();
        
      
    

    }
   
  
   
}```

it works

in my ide

so they should not be a problem

[gleaming sequoia]

it works for me

from cmd

[fervent jolt]

what did you do

[gleaming sequoia]

compiled
put in jar as I wrote above
and run

[fervent jolt]

can you write the command please

[gleaming sequoia]

when you are in project root (suppose it's test directory) you run:```
javac cal/.java
jar cfe my.jar cal.Derivative cal/.class
java -jar my.jar

[fervent jolt]

Yes it works thank you so much

[quiet stream]

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[gleaming sequoia]

np 😉