GUI Programming with Swing

- July 18, 2025

Chapter 13: GUI Programming with Swing in Java

Java Swing is a part of Java Foundation Classes (JFC) that allows you to create rich graphical user interfaces (GUIs). It is built on top of AWT (Abstract Window Toolkit) but provides a more flexible and modern approach.

🌟 Why Use Swing?

Lightweight and platform-independent
Highly customizable
Supports pluggable look and feel

📌 Common Swing Components

JFrame – Main window
JPanel – Container to group components
JButton – Button
JLabel – Text display
JTextField – Single-line text input
JTextArea – Multi-line text input

🔳 Example: Simple GUI


import javax.swing.*;

public class SimpleGUI {
    public static void main(String[] args) {
        JFrame frame = new JFrame("My First Swing App");
        JButton button = new JButton("Click Me");

        frame.add(button);
        frame.setSize(300, 200);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

📦 Layout Managers

Layout Managers control the size and position of components.

FlowLayout – Left to right, line by line
BorderLayout – Divides into 5 regions (N, S, E, W, Center)
GridLayout – Grid of equal-sized cells

🎛️ Event Handling

Event handling is what makes GUIs interactive. You listen for user actions like button clicks or text input.

Example: Button Click Event


import javax.swing.*;
import java.awt.event.*;

public class EventDemo {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Event Example");
        JButton button = new JButton("Click Here");

        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.out.println("Button Clicked!");
            }
        });

        frame.add(button);
        frame.setSize(300, 150);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

🧾 Summary Table

Component	Purpose
JFrame	Main application window
JPanel	Panel to hold UI elements
JButton	Button for actions
JTextField	Single-line input
JTextArea	Multi-line input
JLabel	Displays text

❓ FAQs with Answers:

Q1: What is Swing in Java?

A: Swing is a GUI widget toolkit for Java that provides a rich set of components for building window-based applications.

Q2: How is Swing different from AWT?

A: AWT is heavyweight and platform-dependent, while Swing is lightweight and more versatile. Swing components are written entirely in Java and provide better look and feel.

Q3: What is JFrame?

A: JFrame is the main window container used to create a GUI window in Swing.

Q4: How do you handle button click events in Swing?

A: By adding an ActionListener to the JButton using the addActionListener() method.

Q5: What is a layout manager in Swing?

A: Layout managers automatically position and size components within a container (e.g., FlowLayout, BorderLayout, GridLayout).

Q6: Can we add multiple panels in a JFrame?

A: Yes, you can add multiple JPanel instances to a JFrame and organize them using layout managers.

Q7: Is Swing still used in modern Java apps?

A: While newer frameworks like JavaFX exist, Swing is still widely used for lightweight and educational GUI applications.

📘 Conclusion

Swing empowers Java developers to build feature-rich, responsive desktop applications. With proper use of layout managers and event handling, creating interactive programs becomes easy and powerful.

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