[java] 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.

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

You want:

java -cp myJar.jar myClass

The Documentation gives the following example:

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

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

Where:

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