Question

What is the meaning of purpose of this command java -jar some jar file jar

Answer 1

java -jar <name>

I think this is used when that particular JAR file is needed as part of the execution of a command. 

Comments

You are partially right @Vardhan. This command is used to execute a JAR file. But JAR itself is a Java application in a compressed format.

Answer 2

JAR (Java Archive) file is a package file format that contains many classes, metadata, and resources like image, audio etc., that is necessary for a Java application. A JAR file is a Java application compressed in a single file which contains all the resources required to run a Java application. 

The command mentioned in the question is used to run a JAR file. When you have written a Java program, the command to execute it is:

java <name of the java program file>

Similarly, when you want to execute a Java application that is present as a JAR file, you use the below command:

java -jar <some jar file>.jar

Here, you have to replace <some jar file> with the name of the JAR file. Suppose you want to execute Example.jar, then the command would be:

java -jar Example.jar