ClassNotFoundException when trying to execute a jar

Question

I'm working on a project that allows me to easily read and edit a certain type of file from a sort of terminal. It uses two java files, Main.java and Word.java, which have both been compiled into .class files.

In the folder with my com folder, there is also a bin folder containing a manifest file and another com folder containing the class files.

Here's a sort of visualisation of the file paths:

com vvv
    Main.java
    Word.java
bin vvv
    MANIFEST.MF
    com vvv
        Main.class
        Word.class

The manifest file looks like this:

Manifest-Version: 1.0
Class-Path: .
Main-Class: com.Main
Created-By: 19.0.2 (Oracle Corporation)

To compile it, I use the Visual Studio Code terminal and use the command jar cvfm DictionaryParser.jar bin/MANIFEST.MF bin/com/Main.class bin/com/Word.class

This successfully compiles it into a .jar file. However, whenever I run this jar file, using the command java -jar DictionaryParser.jar, it gives me this error.

Error: Could not find or load main class com.Main
Caused by: java.lang.ClassNotFoundException: com.Main

No matter what I do, this error keeps coming up. Java cmd commands in general are really confusing to me, but I just don't get what I'm doing wrong here. Any ideas? Am I just making a stupid mistake? Keep in mind I don't have much experience with Java compared to other programming languages, especially the JVM.

Answer 1

You're putting your classes in the wrong folder. Here is an example.

This is the incorrect way.

jar cf Test.jar junk/com/Broken.class

Which results in:

$jar tf Test.jar 
META-INF/
META-INF/MANIFEST.MF
junk/com/Broken.class

See the folder structure is incorrect. The package should be the root folder.

The correct way.

jar cf Test.jar -C junk com/Broken.class

Then the jar contains:

$jar tf Test.jar 
META-INF/
META-INF/MANIFEST.MF
com/Broken.class