How to create Jar file in using java commands?

Before looking at how, let’s look into, what is a JAR file?

A JAR file bundles multiple .class files, resources (images, properties), and metadata into one compressed package — similar to a .zip — so it’s easier to distribute and run a Java application.

Steps to Create a JAR File (Using Command Line)

1. Compile your Java code

javac HelloWorld.java

-> This will create a HelloWorld.class file.

2. Create a Manifest file (optional but important for executable JAR)

Create a file named manifest.txt with this content:

Main-Class: HelloWorld

-> Ensure there is a blank line at the end of the file (important for correct manifest format).

3. Create the JAR file

Now, use the jar command:

jar cfm MyApp.jar manifest.txt HelloWorld.class

Where:

• c → Create new JAR
• f → Specify output file name
• m → Include manifest file
• MyApp.jar → Name of the jar file
• manifest.txt → Manifest file you created
• HelloWorld.class → Compiled class(es) to include

4. Run the JAR file

java -jar MyApp.jar

Examples of Other Common jar Commands

Purpose	Command
Create JAR without manifest	jar cf MyLib.jar *.class
View contents of a JAR	jar tf MyApp.jar
Extract JAR contents	jar xf MyApp.jar
Update existing JAR	jar uf MyApp.jar NewClass.class