How do I create a jar file via the command line?

Question

Lets say I have these .java files:

Then I turn them into .class files:

How would I make it a jar file, and have MainClass.class be the first to be loaded?

You would not. You would first compile your .java files to .class files. You would then create a [manifest file](https://docs.oracle.com/javase/tutorial/deployment/jar/manifestindex.html). Finally you would jar the class files and specify the manifest file. Documentation is at the link provided. — Elliott Frisch, Jul 07 '21 at 23:41
I would suggest you to check Maven or Gradle, that will help you like nothing else — Alberto Sinigaglia, Jul 07 '21 at 23:42
Please, check this [answer](https://stackoverflow.com/a/10132818/8370915). It might be helpful for you. — invzbl3, Jul 07 '21 at 23:55

score 3 · Accepted Answer · answered Jul 07 '21 at 23:58

Observing what Elliott said about class files, you can create (in recent versions of jar) the manifest implicitly with

jar cvfe m.jar MainClass *.class

That assumes that MainClass is in the default package ('no package') (not good practice). That will then run with

java -jar m.jar

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