How to Create JAR file in Java and also using Eclipse

Let us see how to create a JAR file using Java’s jar command as well as using Eclipse IDE. The JAR file format is based on the popular ZIP file format. Usually these file are used for archiving and distribution the files and implementing various libraries, components and plug-ins in java applications. Compiler and JVMs (Java Virtual Machine) can understand and implement these formats for java application.

Create a JAR file

jar cf JAR_FILE_NAME FILE_NAMES_OR_DIRECTORY_NAME   Eg: jar cf MyApp1.jar C:\MyProject\MyApp

View contents of a JAR file

jar tf JAR_FILE_NAME   e.g. jar tf MyProject.jar

View contents with detail of a JAR file

jar tvf JAR_FILE_NAME e.g. jar tvf MyProject.jar

Note that we have used v (verbose) option to see the detail of JAR.

Extract content of JAR file

jar xf JAR_FILE_NAME e.g. jar xf MyProject.jar

Extract specific file from JAR file

jar xf JAR_FILE_NAME FILE_NAME(S)_FROM_JAR_FILE e.g. jar xf MyProject.jar Test1.class

Update a JAR file

jar uf JAR_FILE_NAME FILE_NAMES_FROM_JAR_FILE e.g. jar uf MyProject.jar Test1.class

Executing a JAR file

java -jar JAR_FILE_NAMEe.g. java -jar MyProject.jar

Create an executable JAR file

In order to create an executable JAR, one of the classes that we include in our JAR must be a main class.
Create a text file called MANIFEST.MF using any text editor and copy following content in it.

Manifest-Version: 1.0 Main-Class: MyMainClass

Where MyMainClass is the name of the class that contents main method. Also note that you have to specify fully qualified class name here.
Use following command to create an executable JAR file.

jar cvfm MyProject.jar MANIFEST.MF FILE_NAMES_OR_DIRECTORY_NAME