What Is Applet in Java? A Comprehensive Guide

What Is Applet In Java? 

A Java application that is integrated into a webpage is called an applet. It functions as a front-end and is run within the web computer. It makes a page more interactive and dynamic by operating inside the web browser. Applets are hosted on web servers and inserted into HTML pages via the OBJECT or APPLET tags.

It can be compared to a tiny application that runs on the address bar. In addition to updating content in real-time and responding to human input, it may also play basic puzzles or graphics.

The Life Cycle Of An Applet

The process by which an object is developed, launched, halted, and demolished throughout an application's implementation is known as the applet life cycle in Java. In essence, it has five main methods: paint(), destroy(), stop(), init(), and start().The browser calls these methods in order to perform their 

actions.

1. Init()- The init() function is the first to be executed and is responsible for initializing the applet. It can only be called once throughout the startup process. The initialized objects are created by the web browser, which executes the init() function located inside the applet after confirming the authentication setting.

2. Start()- This function launches the applet and includes the applet's real code. It begins directly following the call to the init() function. The start() function is called each time the browser loads or refreshes. Additionally, it is triggered when the applet is relaunched, improved, or switched across tabs in the web interface. Until the init() function is used, it is in an idle state.

3. Stop()- The applet's execution is terminated by using the stop() function. Every time the applet is minimized, paused, or switched between tabs on the web page, the stop() function is triggered. Again, the start() function is called when we return to that page.

4. Destroy()- Once the applet completes its task, the destroy() function terminates it. When the webpage-containing tab closes, or the applet window closes, it is triggered. It is performed just once and expunges the applet data from RAM. We can't restart the applet after it's been deleted.

5. Paint()- The Java Graphics class contains the paint() function. It is employed in the applet to draw forms like squares, circles, trapeziums, and so on. It runs following the call to the start() function and whenever the web page or applet display resizes.

Types of Applets

Java applets can be classified as either local or remote, depending on where they are stored and how easily they can be accessed.

1. Local Applet

We will write the Local Applet ourselves and then integrate it into websites. A local applet is created locally and kept on the local machine. When a web page detects a local applet in the Java system's memory, it does not need to obtain data directly from the internet in order to function. It is defined or provided by the pathname or folder name. When constructing an applet, two properties are used: the source folder, which defines the path name, and the code itself, which defines the filename containing the applet's programming.

2. Remote Applet

The remote applet is stored or accessible on another computer that is linked to the world over the internet. We must have internet access on the system to be able to obtain and use the applet that resides on the other machine. We need to be familiar with a remote applet's Uniform Resource Locator (URL) or web location in order to find and download it.

Simple Applet Program In Java

"Hello, World" is a well-known illustration of a basic applet program in Java. The code is as follows:

Java

import java. applet.*;
import java. awt.*;
public class HelloWorld extends
Applet
{
  public
void
init()
{
    setBackground(Color.white);
  }
  public
void
paint(Graphics g)
{
    g.setColor(Color.black);
    g.drawString("Hello, world!", 50, 50);
  }
}

Advantages Of Java Applets

1. Interaction With Browsers

Through a smooth integration with online sites, applets let viewers engage with dynamic information without exiting the browser. This results in improved customer service while eliminating the need to obtain and set up separate programs.

2. Diminished Server Traffic

Local execution of the applet's code allows functionality to occur on the front end or the user's workstation. In doing so, the server's workload is lessened, and it can process more inquiries and users at once.

3. Availability

Applets may adjust to changing frequency bands and computing power. They can be compact and quick to load for users with poorer interactions while providing more capability for those with greater capabilities.

Disadvantages Of Java Applets

1. Utilizing Excessive Performance And Resources

A common complaint about Java applets is their resource use, particularly with complicated ones. In certain situations, they can even cause crashes, hinder browser performance, and deplete the gadget's batteries. This slowness and waste of resources are not acceptable in today's performance-driven online environment.

2. Insufficient Development Support

Application interest declined when major browsers discontinued supporting applets. Suppose you compare applet programming to contemporary website creation tools. In that case, it becomes less appealing and more difficult due to the decreased availability of programming frameworks, libraries, and debugging resources.

3. Security Flaws

Because of their architecture, applications operate inside the user's browser and provide access to a greater variety of resources than web pages. But this authority has a cost: possible security lapses. Fraudulent applets might exploit vulnerabilities to get access to private information, download malware, or interfere with system functions.

How To Run An Applet Through An HTML File?

Despite their popularity on the web, Java applets still need to be rendered obsolete by security flaws. Most browsers no longer support them, making them a hazardous and obsolete technology. 

Here's a brief overview if you must run an applet, however:

• Prepare your applet as follows: Ensure that you have the Java Running Environment installed, then compile your code and include it within the HTML code file.
• Make the HTML: Enter the parameters, required resources, and. class name using the <applet> tag.
• Execute the HTML: Check if it works by opening it in a browser that remains compatible with applets and accepting prompts.

How To Run An Applet Using The Appletviewer Tool?

Though they are no longer as popular on the web, Java applets may still be used with the help of the handy applet viewer application. It can be used as follows:

• Prepare to Install Java and locate the—class file from your generated applet.
• Gather around, command line! To access the directory containing the.class file, open your terminal, browse there, and write an applet viewer. The applet window pops up!
• Run applets from HTML files using applet viewer, see troubleshooting information with -debug, and customize with the -J switch.

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Conclusion

To summarize, the Java applet idea has played an important part in the development of the web. When applets were first introduced, they offered a method to add dynamic and lightweight elements to web pages. They also allowed users to add interactive and eye-catching material straight into their browsers. But as web technologies have advanced and security concerns have grown, applets have lost some of their luster in contemporary Java programming. 

While the world of Java applets is gone, the invaluable lessons learned from its time are carried forward by developers who continue to seek out fresh and creative ways to solve problems as technology progresses.

If you are looking to enhance your Java skills further, we would highly recommend you to check Simplilearn’s Full Stack Java Developer program. In collaboration with IBM, this program can help you gain all the right skills and make you job-ready. 

If you have any questions or queries, feel free to post them in the comments section below. Our team will get back to you at the earliest.

FAQs

1. What are the alternatives to Java applets for web development?

The alternatives to applet in Java for web development are:

• JavaScript
• WebAssembly
• WebGL
• Web Components
• SVG and Canvas

2. Are Java applets still used today?

Java applets have seen a considerable decrease in application and acceptance over the years. Several causes, including safety-related issues, can be attributed to the fall.

3. Are there any security risks associated with Java applets?

Java applets have indeed been linked to vulnerabilities in security. They contain flaws that bad players could use to inject illegal code into an individual's computer. 

4. Can I run Java applets on mobile devices?

It may not be easy to run Java applets promptly on contemporary mobile devices. Many mobile phones, such as iOS and Android, do not support Java applets because of safety considerations and the move toward enhanced security and efficiency technologies.