Short Answer
An applet is a small program that runs inside a web browser. It’s like a tiny app you can use without having to install it on your computer. Applets are written in Java, so they can run on any type of computer or device that has Java. They’re used for simple games, calculators, and other interactive tools on websites. However, modern web development has moved away from applets because of security concerns and the rise of more versatile technologies.
Applets have a special life cycle, which means they go through specific stages from starting up to shutting down. When an applet starts, it initializes, then begins to run. If it needs to stop, like when you close the web page, it pauses. Later, it can start running again if the page is reopened. Finally, when it’s no longer needed, the applet is destroyed. This cycle helps manage the applet’s resources and ensures it runs smoothly without taking up too much memory or processing power.
Detailed Answer
What is an Applet?
An applet is a small Java program that is embedded in a web page and runs in the web browser. It allows users to have an interactive experience while browsing the web. Unlike standalone applications, applets do not require installation on a computer; they are automatically loaded and executed by the browser when the user visits a page containing an applet.
Life Cycle of an Applet
The life cycle of an applet is governed by four main methods defined in the Applet class:
- init(): This method is called first. It is used for initialization purposes. When an applet begins,
init()sets up the environment, such as loading images or fonts. It’s like setting up your desk before starting work. - start(): After
init(), thestart()method is called. This method kicks off the applet’s execution, often starting animations or threads. It’s like actually starting your workday after setting up your desk. - stop(): If a user leaves the page or the applet needs to pause for any reason, the
stop()method is called. This method pauses the applet, saving resources. It’s similar to taking a break during work. - destroy(): This method is called when the applet is no longer needed. It cleans up resources and prepares the applet to be removed. Think of it as cleaning up your desk and shutting down your computer at the end of the day.
Examples in Real Life
A common example of an applet could be a game like a small puzzle or chess that you play on a webpage. Another example is a financial applet that calculates loan interest in real-time as you input different values.
Important Points with Examples
- Security and Applets: Applets run in a secure environment called a “sandbox,” which limits what they can do for security reasons. For example, an applet might display a graph of data but cannot access the files on your computer.
- Usage Examples: In the past, applets were commonly used for interactive content like games, chat applications, and complex calculators. A website with a mortgage calculator might have used an applet to let users input different interest rates and loan amounts.
- Decline of Applets: With the advancement of web technologies such as HTML5, CSS3, and JavaScript frameworks, the use of applets has significantly declined. These technologies offer similar functionalities without requiring Java to be installed on the client’s machine, making them more accessible and secure.
In conclusion, applets were a pioneering technology for interactive web content, demonstrating the power of Java for web applications. Despite their decline in use due to newer web technologies, understanding applets and their life cycle is important for grasping the evolution of web development and the concept of running applications within a browser.