Java Applets vs. Java Applications: Key Differences Explained

Java is a versatile and widely-used programming language, and its applications can vary in their design and execution environments. Two primary forms of Java programs are Java applets and Java applications. This article delves into the differences between these two types of Java programs, highlighting their distinct characteristics and environments.

Key Differences

1. Execution Environment

Java Applet: Runs inside a web browser or an applet viewer. Designed to be embedded in web pages, enabling interactive features on websites.
Java Application: Runs as a standalone program, which can be executed directly from the command line or through a graphical user interface (GUI) without the need for a web browser.

2. User Interface

Java Applet: Typically has a graphical user interface (GUI) that is rendered within the web page. However, it faces security restrictions that limit its access to system resources.
Java Application: Can have a more complex and rich GUI using libraries like Swing or JavaFX. It has full access to the system's resources, allowing for more extensive functionality.

3. Lifecycle

Java Applet: Has a defined lifecycle with methods such as init(), start(), stop(), and destroy() to manage its execution. The applet is loaded and executed by the browser, which manages its lifecycle.
Java Application: Typically has a main() method that serves as the entry point for execution. The application runs until the main() method completes or the user closes it.

4. Deployment

Java Applet: Requires a web server to host the HTML page that includes the applet. Users need a Java-enabled browser or Java plugin to run the applet.
Java Application: Can be distributed as a standalone JAR file or executable. Users need to have the Java Runtime Environment (JRE) installed, but it does not depend on a web browser.

5. Security Restrictions

Java Applet: Runs in a sandboxed environment to prevent malicious actions. This limits its access to the local file system and network.
Java Application: Generally has fewer restrictions and can access system resources more freely provided the user has granted the necessary permissions.

Conclusion

In summary, Java applets are designed for web integration and run in a browser with security restrictions, while Java applications are standalone programs that can leverage the full capabilities of the Java platform, including deeper system access and more complex user interfaces. While the use of applets has declined significantly due to security concerns and the rise of alternative web technologies like JavaScript and HTML5, understanding the fundamental differences between applets and applications remains crucial for developers working with Java.