Difference Between Applet and Application in Java

Java is a multi-purpose and multi-faceted language as it contains different types of programs. Two major types of programs that can be written in Java are Applets and Applications. Although both can be developed in the Java language, they have or will serve different purposes, have varied features, and will target different audiences and scenarios. For Java developers, knowing the difference between an Applet and an Application is very important.

In this article, we will compare the differences between the Applet and Application in Java, learn the key differences, execution environment, security features, examples, and more.

Introduction to Java Programs

Java is a multi-paradigm, multi-environment language which makes it applicable in cases of many applications. In Java, programs are broadly categorized into two types depending on how they are executed: Applets and Applications.

• Applications: They are self-contained or stand-alone programs that are run on the client machine or the user’s local machine. It utilises the entire system resources available.
• Applets: They are small Java programs that are contained within another document or web page and can be run within a browser or in an applet viewer.

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An Applet is defined as a Java application meant to be executed within a web browser or embedded within web pages. Unlike traditional Java applications, java applets are contained in a controlled environment that restricts operations like accessing files and making network calls to unidentified services. This environment is usually a browser, an applet viewer, or an HTML webpage using <APPLET> tag. The Java Virtual Machine on the computer is used by a web browser that supports Java to compile and execute the Applet code. The following methods are executed by a Java applet: init(), start(), and paint().

Characteristics of Applet

• Web-based execution: An online page loads and launches an applet.
• Limited access: Applets have restricted access to the host system’s resources like OS, etc., because they operate in a sandbox.
• Interface Graphical: Button, form, and other interactive elements are common graphical features found in applets.
• Absence of a main() method: Applets operate without a main() method, in contrast to standard Java applications.

How does Applet Work in Java?

Applet has a lifecycle in Java, which means they are initialized first, then start, stop, and finally destroyed to complete the lifecycle. Here is the working of an Applet:

1. Initialization: When the applet loads for the first time, the init() method is called once.
2. Start: The start() method is called each time the applet activates.
3. Stop: The stop() method is triggered when the applet is hidden or not in use.
4. Destroy: The destroy() method is invoked during the process of removing an applet from memory.

Example:

To run the applet program, we have to compile the Java file by running the below javac command in the terminal:

javac HelloHeroVide.java

What is a Java Application?

A Java application is a standalone software that functions on a user’s computer without assistance. It could be a backend server application, a desktop GUI program (like Swing or JavaFX), or even a command-line tool. Java Virtual Machine, or JVM, is used to compile and execute the code. It is often stored in the system on which it is operating and uses the system’s resources following the Java security paradigm. Applications can access memory, files, and network connections without any limitations.

Characteristics of Java Application

• Java applications are not reliant on web browsers as they are standalone applications and are launched via the Java Virtual Machine (JVM).
• Applications have complete access to all system resources, including databases, local files, and network resources.
• Java applications need to have a main() method as their entry point for execution.
• Java programs have the option of being console-based or graphical user interface (GUI)-based.

Example:

Output:

Key Differences Between Applet and Application

Execution Environment

Applet Environment

There are two means by which applets can be executed i.e., using web browsers or special viewers (like the appletviewer tool). Whenever an HTML page containing an applet is opened, the class file of the applet is fetched from the server and run by the web browser in a restricted area termed a sandbox. The meaning of sandboxing is that any applet downloaded from the network cannot carry out any operations such as reading a local directory structure or opening network connections to computers other than the one from which the applet was downloaded.

Application Environment

Java applications run on the user’s system in conformity with the installed JVM. There is no web page required for such a process to be effective. Command line or by the use of a double click on a given executable .jar which runs it automatically can be used by users to execute Java applications. The system resources that are accessible by applications include but are not limited to local files, network connections, printers.

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Conclusion

Applets and applications have their different roles in Java programming, however, due to the growth of web technologies and the extinction of Java browser plugins, the use of applets is no longer feasible. On the other hand, Java applications are very much used today, especially when it comes to enterprise software and backend systems. Developers need to be aware of the difference between an applet and an application so that they can opt for what fits well with their projects.