APPLETS & ABSTRACT WINDOW TOOLKIT - I

Summary

The video script covers key Java technical questions and answers related to applets, focusing on their usage within web pages to enhance interactivity. It explains the lifecycle methods of an applet, such as init, start, paint, stop, and destroy, and how these methods are used for initializing, displaying content, and managing applet execution across web pages. The script also discusses methods for managing the applet's appearance, such as setting foreground and background colors, and the process of embedding an applet within an HTML page using specific tags and parameters.

Takeaways

• 📱 Java applets are small programs embedded in web applications to enhance interactivity with elements like animations and games.
• 🌐 Applets are used to make web pages more interactive and user-friendly, often involving scrolling images and animations.
• 🔄 The life cycle of an applet consists of four key methods: init, start, stop, and destroy, each playing a specific role in applet management.
• 🛠️ The init method is called when the applet starts and is used for initializing variables and components such as labels, buttons, and checkboxes.
• ⚡ The start method is called after the init method, when the applet begins execution or is resumed after being paused.
• 🖼️ The paint method is responsible for rendering output on the applet window using the Graphics class to handle visual elements like lines or text.
• 🚫 The stop method is called to pause the applet when the user switches between web pages, and it resumes when the user returns.
• 🛑 The destroy method is used to release resources and perform cleanup operations before the applet is terminated.
• 💡 The showStatus method displays information on the status bar, while drawString is used to display text at specific coordinates on the applet window.
• 🎨 Methods like setBackground and setForeground are used to control the background and text colors of the applet window.

Q & A

What is an applet in Java?

An applet is a program typically embedded within another application, such as a web tool, to make web pages more interactive. It can include elements like animations, games, and scrolling images.

What are the four life cycle methods of an applet?

The four life cycle methods of an applet are `init()`, `start()`, `stop()`, and `destroy()`. These methods manage the different stages of the applet's execution.

What is the purpose of the `init()` method in an applet?

The `init()` method is called when the applet begins execution. It is used to initialize variables and components like labels, buttons, and checkboxes. This method is called only once during the applet's life cycle.

What does the `start()` method do in an applet?

The `start()` method is called after the `init()` method when the applet first starts. It can also restart the applet if the user navigates away and then returns to the applet’s page.

When is the `stop()` method used in an applet?

The `stop()` method is called to suspend the execution of the applet, such as when a user navigates away from the web page where the applet is running. It pauses the applet until the user returns.

What is the function of the `destroy()` method in an applet?

The `destroy()` method is used to release any resources held by the applet before it is terminated. It is called when the applet is about to be closed, and cleanup operations can be performed here.

What is the `paint()` method used for in an applet?

The `paint()` method is used to display output on the applet window, such as text or graphics. It takes a `Graphics` parameter, which contains the graphics context that can be used to draw lines, shapes, and text.

Which method is used to display information in the status window of an applet?

The `showStatus()` method is used to display information in the applet’s status bar, typically located at the bottom of the window.

How do you change the background color of an applet window?

The `setBackground(Color color)` method is used to change the background color of an applet window. For example, `setBackground(Color.green)` sets the background to green.

What is the purpose of the `param` tag in an applet?

The `param` tag is used to pass parameters to the applet. These parameters can be accessed within the applet using the `getParameter(String name)` method. Each `param` tag contains a name and a value.