A Detailed Guide To The Applet Life Cycle In Java

An applet is a Java program that can be embedded into a webpage. It runs inside the web browser and helps generate dynamic content. This is embedded in an HTML page using the APPLET or OBJECT tag from the web server. It makes the webpage more interactive and updates the content in real-time. Along with its function to respond to human input, it can also play basic puzzles and graphics. It functions as a front end and can be compared to an application running in the address bar. This article will explain the life cycle of applets in Java for those who are unfamiliar.

What is the life cycle of an applet in Java?

The applet life cycle in Java encompasses the entire execution process of an application. This process involves the development, launching, termination, and destruction of an object. It has five core methods, namely, init(), start(), stop(), paint(), and destroy(). The browser uses these five main methods to perform actions. Additionally, the applet also works on the client side and has less processing time.

Types of applets in Java

The Java language has two types of applets: the local applet and the remote applet.

1. Local Applet

A local applet is an applet that developers write separately and then embed into web pages. The distinguishing feature of local applets is that developers create them locally and store them on the local system, and these applets do not fetch information from the internet. Rather, it is specified by the local file name. 

2. Remote Applet

A remote applet means one designed by a developer and not the Java team. On the other hand, some applets are stored remotely on another computer. To download and run these applets, you need a consistent internet connection. You can load these applets only if you know their URL on the web.

To make a normal Java class into an applet class, you need to extend the applets.

Also read – I Hate Computer Science: Why Some Students Struggle With Coding?

Stages in the Life Cycle of Java Applet

The five main stages in the life cycle of an applet in Java are mentioned below.

Init()

public void init()
 {
 // To initialize objects
 }

The Init() function, which initializes the applet, is the first function to execute in this life cycle. After execution, web browsers create these initialized objects. The web browser executes this Init() function inside the applet, confirming the authentication setting.

Start()

public void start()
 {
 // To start the applet code
 }

This function launches the applet and has its real code. The Start() function takes over after the Init() function. It launches the applet and contains its real code. Every time you load or refresh the browser, this function executes. Furthermore, the function also activates whenever the applet is relaunched, or improved, or when you switch tabs in the web interface. However, until the Init() function is used, the Start() function remains inactive.

Stop()

public void stop()
 {
 // To stop the applet code
 }

Once the Start() function is running, the Stop() function can terminate an applet’s execution. This termination happens every time you minimize, pause, or switch between tabs. Furthermore, when you return to the previous page, the Start() function is triggered once again.

Destroy()

public void destroy()
 {
 // To destroy the applet
 }

After completing all necessary tasks, the Destroy() function terminates the applet permanently. This function triggers whenever you close the tab of a particular web page or the applet window. Notably, it removes all applet data from RAM, and you cannot restart an applet once deleted.

Paint()

public void paint(Graphics graphics)
 {
 // Any shape's code
 }

Lastly, the Paint() function, part of the Java Graphics class, helps to draw shapes such as squares, circles, etc., in the applets. The Start() function triggers the running of the Paint() function. It also operates whenever you resize the web page or applet display.

Understanding the life cycle of an applet in a Java diagram is way easier. With the creation of an applet class, users can utilize all the methods of that specific class. Additionally, users don’t need to manually call the methods of the applets, as the web browser triggers them automatically.

Conclusion

It is necessary to understand the applet life cycle in Java to understand and develop Java applets. With a thorough understanding and utilization of these methods of the life cycle, one can handle user interactions and perform cleanup tasks.

The methods listed above form the applet life cycle and provide hooks for managing the behavior and functions of the applets. Proper utilization of these features will create dynamic and interactive apps to improve the overall experience of the users.