Run class in Jar file


If you have a jar file called myJar.jar located in /myfolder and you want to use the class called myClass from it, how do you go about doing it from the command line?

I thought it would be to go into the directory and say java -cp myJar.jar.myClass but that isn't working. Any help would be appreciated.

4/13/2017 7:31:26 PM

Accepted Answer

Use java -cp myjar.jar com.mypackage.myClass.

  1. If the class is not in a package then simply java -cp myjar.jar myClass.

  2. If you are not within the directory where myJar.jar is located, then you can do:

    1. On Unix or Linux platforms:

      java -cp /location_of_jar/myjar.jar com.mypackage.myClass

    2. On Windows:

      java -cp c:\location_of_jar\myjar.jar com.mypackage.myClass

2/10/2014 6:49:18 PM

You want:

java -cp myJar.jar myClass

The Documentation gives the following example:

C:> java -classpath C:\java\MyClasses\myclasses.jar utility.myapp.Cool

There are two types of JAR files available in Java:

  1. Runnable/Executable jar file which contains manifest file. To run a Runnable jar you can use java -jar fileName.jar or java -jar -classpath abc.jar fileName.jar

  2. Simple jar file that does not contain a manifest file so you simply run your main class by giving its path java -cp ./fileName.jar MainClass


Assuming you are in the directory where myJar.jar file is and that myClass has a public static void main() method on it:

You use the following command line:

java -cp ./myJar.jar myClass


  1. myJar.jar is in the current path, note that . isn't in the current path on most systems. A fully qualified path is preferred here as well.

  2. myClass is a fully qualified package path to the class, the example assumes that myClass is in the default package which is bad practice, if it is in a nested package it would be com.mycompany.mycode.myClass.


This is the right way to execute a .jar, and whatever one class in that .jar should have main() and the following are the parameters to it :

java -DLB="uk" -DType="CLIENT_IND" -jar com.fbi.rrm.rrm-batchy-1.5.jar

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