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.
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:
Initialization: When the applet loads for the first time, the init() method is called once.
Start: The start() method is called each time the applet activates.
Stop: The stop() method is triggered when the applet is hidden or not in use.
Destroy: The destroy() method is invoked during the process of removing an applet from memory.
Example:
import java.applet.Applet;
import java.awt.Graphics;
public class HelloHeroVide extends Applet {
public void paint(Graphics g) {
g.drawString("Hello, HeroVide!", 20, 20);
}
}
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:
public class MainExample {
public static void main(String[] args) {
int a = 10, b = 20;
int res = a + b;
System.out.println("The sum of the two given numbers is:" + res);
}
}
It is executed in a standalone JVM (Java virtual machine).
Main method
There is no main() method.
It requires main() method.
Security
Runs in a sandbox with restricted permissions.
Full access to system resources
GUI
It uses AWT/Swing; embedded in a webpage.
It can be GUI-based using AWT/Swing/JavaFX.
Lifecycle Methods
It has methods including init(), start(), stop(), and destroy().
It has only the main() method.
Resource Access
It has limited access to the resources of a system.
It has full access to the local file system and network.
Interaction
Embedded in a web page; a user interacts via browser.
A user interacts through GUI or command-line.
Running Context
Needs a web browser or applet viewer to execute.
Executes independently as a standalone program.
Network Access
Restricted network access.
Unrestricted network access.
Programming
We can create Java applets with message displays.
Applications in Java that add two numbers can be created.
Connection
In Java, for applets, creating a connection server is impossible.
In Java, creating a connection server is possible for applications.
Access Level
Applets lack network and local drive connectivity.
Applications written in Java have access to every resource on the system.
Compilation
Java Compiler is used to compile Java applets, and a web browser that supports Java is used to run them.
The Java compiler (Java virtual machine) is used to compile and run Java applications.
Restrictions
These have easy access to any file or data stored on a device or computer system.
These are unable to access any file or data that is stored on local or system computers.
Security
Applets for Java are not particularly reliable. They therefore need security.
Java apps don’t raise any security issues because they are generally reliable.
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.
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.
FAQs
What is the main difference between applets and applications in Java?
Java applications are programs that run on a system without any web browser. Java Applets are the programs that need a Java-supported web browser for their execution.
Why are Applets deprecated in modern browsers?
This is because modern browsers do not support Java plugins anymore, which is what applets need to run in them. The use case for replacing applets with HTML5, JavaScript, or WebAssembly technologies provides interactive web content.
Can Applets access local files?
No, until they have specific authorization, applets operate in a sandbox environment that prevents them from accessing local files or carrying out other potentially dangerous tasks.
What is the entry point of a Java Application?
Java programs begin running from the main() function, which acts as the program's entry point.
What are the use cases for Java Applications today?
Java programs are widely utilised for server-side solutions, desktop applications, and enterprise software, especially in the financial, medical, and e-commerce sectors.
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