Create Executable Jar File
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Create Executable Jar File


When you try to run the JAR file with below command, lets assume that the JAR file is named as example-0.0.1.jar.

java -jar example-0.0.1.jar

no main manifest attribute, in example-0.0.1.jar

Let's extract the contents of the JAR file as this is just a ZIP file with below command. You may see some output like below as every project is quite different.

unzip example-0.0.1.jar

Archive:  example-0.0.1.jar
   creating: META-INF/
  inflating: META-INF/MANIFEST.MF    
   creating: META-INF/maven/
   creating: META-INF/maven/com.codingjump/
   creating: META-INF/maven/com.codingjump/hello-world/
  inflating: HelloWorld.class        
  inflating: META-INF/maven/com.codingjump/hello-world/pom.xml  
  inflating: META-INF/maven/com.codingjump/hello-world/  

To fix this we need to add a manifest file which points to the Main class. We can make use of the maven-jar-plugin for adding META-INF/MANIFEST.MF file so that when we run the JAR directly it works.

Currently it is almost blank.

Manifest-Version: 1.0
Created-By: Maven JAR Plugin 3.3.0
Build-Jdk-Spec: 20

Now lets use the maven-jar-plugin and define the mainClass as below.


Now if you build your JAR file should have following contents in META-INF/MANIFEST.MF

Manifest-Version: 1.0
Created-By: Apache Maven 3.9.4
Built-By: snrahul11
Build-Jdk: 20.0.2
Main-Class: HelloWorld

Now we have a attribute called Main-Class which defines our starting point for JAR file. Now if you run the JAR file you should see some output on the console.

java -jar example-0.0.1.jar

Hello World!!!

Similarly we can make use of spring-boot-maven-plugin with the below syntax.

          <mainClass> com.codingjump.Program</mainClass>

It works quite similar to the maven-jar-plugin. You can follow this post if you want to learn more about Spring Boot Command Line Application.


Hope this has gives you some basic understanding of how you can create a executable JAR file. There are many things which we need to learn about JAR packaging, etc. But I believe this is enough to give you a head start towards Java Development.