What is JAR File and How to create JAR File

A JAR File, stands for Java Archive file. Like ZIP file, JAR is compressed file format, which is used to share software resources required for Java Applications. For example Hibernate, Struts, Spring,etc… provide their framework implementation through multiple JAR files. Similarly you can provide Jar files to your clients, or other Teams dependent on your Classes or packages. Even JDBC driver is provided as a Jar file. A Jar file may contain
1. bunch of .class files
2. any other resource files, like images, icons,etc… required by .class files

Also note that a jar file can have multiple packages or sub packages.

How to create JAR file in Eclipse

Below are the steps involved in creating jar file in Eclipse IDE.
1. Create a Java Project
2. Add class Files
3. Build the Project, do Testing
4. Right click on Project, and Select Export

export jar file
export jar file

5. In Export Window, select java, then JAR file, then Next button.
create-jar
create-jar

6. Now Below JAR File Specification window appears. Select various options, based on your requirement.
Select or unselect appropriate checkbox to specify if you want to Export generated class files and resources or Export Java source files and resources as well.

jar-file-specification
jar-file-specification

Browse to select a location for the JAR file, which will get created.

Select or unselect, Compress the contents of the JAR file checkbox.
Select or unselect, Overwrite existing files without warning checkbox. If you unselect this checkbox, then you will be prompted to confirm the replacement of each file that will be overwritten.

In this way you can create JAR file, out of your class files, and other required resources, and distribute it.

You may also like to read:

How to Compress and Uncompress file in Java


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