Difference between WAR and JAR in Java

1. Introduction

In Java, both WAR and JAR files are used to package components. A JAR (Java ARchive) is a package file format used to aggregate many Java class files and associated metadata and resources into one file for distribution. A WAR (Web Application aRchive) is a file format used specifically to package web applications.

2. Key Points

1. JAR files are used to aggregate Java classes for libraries, utilities, and console applications.

2. WAR files are specifically designed to package web applications so that they can be deployed on any servlet/JSP container.

3. JAR files contain .class files and optionally a manifest file and other resources.

4. WAR files contain JSPs, HTML, JavaScript, and other files necessary for web applications, including a WEB-INF directory with a web.xml file.

3. Difference between WAR and JAR in Java

Used for packaging libraries and console applications. Used for packaging web applications.
Does not have a specific internal structure for application components. Has a specific structure, with a WEB-INF folder for deployment descriptors.
Can be used as a library and included in WARs. Is deployed to servlet containers and includes JAR libraries.

4. When to use?

- Use JAR files when you need to distribute your Java application or library for use in other Java projects.

- Use WAR files when you are developing web applications that you want to deploy to any servlet/JSP container.