Swing Components

✅ What is Swing?

• Swing is a part of Java Foundation Classes (JFC) used to create Graphical User Interfaces (GUIs).

• It is platform-independent, lightweight, and more flexible than the older AWT.

🧩 Commonly Used Swing Components

🧠 Note

• All Swing components are part of the javax.swing package.

• They are lightweight and written entirely in Java.

• You can customize components using colors, fonts, tooltips, icons, etc.

🧪 Example: Simple Registration Form

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

public class RegistrationForm {
    public static void main(String[] args) {
        // Create the frame
        JFrame frame = new JFrame("Registration Form");

        // Create components
        JLabel nameLabel = new JLabel("Name:");
        nameLabel.setBounds(30, 30, 80, 25);
        JTextField nameField = new JTextField();
        nameField.setBounds(120, 30, 150, 25);

        JLabel genderLabel = new JLabel("Gender:");
        genderLabel.setBounds(30, 70, 80, 25);
        JRadioButton male = new JRadioButton("Male");
        male.setBounds(120, 70, 60, 25);
        JRadioButton female = new JRadioButton("Female");
        female.setBounds(180, 70, 80, 25);
        ButtonGroup genderGroup = new ButtonGroup();
        genderGroup.add(male);
        genderGroup.add(female);

        JCheckBox agreeBox = new JCheckBox("I agree to the terms.");
        agreeBox.setBounds(30, 110, 200, 25);

        JButton submitButton = new JButton("Submit");
        submitButton.setBounds(100, 150, 100, 30);

        // Add action to button
        submitButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (agreeBox.isSelected()) {
                    String name = nameField.getText();
                    String gender = male.isSelected() ? "Male" : female.isSelected() ? "Female" : "Not selected";
                    JOptionPane.showMessageDialog(frame,
                        "Name: " + name + "\\nGender: " + gender,
                        "Registration Successful",
                        JOptionPane.INFORMATION_MESSAGE);
                } else {
                    JOptionPane.showMessageDialog(frame, "Please agree to the terms.");
                }
            }
        });

        // Add components to frame
        frame.add(nameLabel);
        frame.add(nameField);
        frame.add(genderLabel);
        frame.add(male);
        frame.add(female);
        frame.add(agreeBox);
        frame.add(submitButton);

        // Frame settings
        frame.setSize(350, 250);
        frame.setLayout(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

🧠Explanation of the code:

📥 Import Statements

• import java.awt.event.*;

  • import javax.swing.*;

    ➤ Imports all the Swing classes like JFrame, JLabel, JTextField, JRadioButton, JCheckBox, JButton, JOptionPane.

  ➤ Imports event-handling classes such as ActionEvent and ActionListener used to respond to user actions like button clicks.

🔧 Basic Setup

• JFrame frame = new JFrame("Registration Form");

  ➤ Creates the main window titled "Registration Form", which serves as the container for all UI components.

🏷️ UI Components

• JLabel nameLabel = new JLabel("Name:");

  ➤ Displays a label prompting the user to enter their name.

• JTextField nameField = new JTextField();

  ➤ Allows the user to enter a single-line text input (their name).

• JLabel genderLabel = new JLabel("Gender:");

  ➤ Displays a label for gender selection.

• JRadioButton male = new JRadioButton("Male");

  ➤ Radio button option to select Male as gender.

• JRadioButton female = new JRadioButton("Female");

  ➤ Radio button option to select Female as gender.

• ButtonGroup genderGroup = new ButtonGroup();

  ➤ Groups the gender radio buttons to ensure only one can be selected at a time.

• JCheckBox agreeBox = new JCheckBox("I agree to the terms.");

  ➤ Checkbox that the user must check to agree to the terms and conditions.

• JButton submitButton = new JButton("Submit");

  ➤ Button that, when clicked, performs input validation and displays results.

🎯 Positioning Components

• setBounds(x, y, width, height);

  ➤ Manually positions and sizes each component on the frame using absolute pixel-based layout.

🖱️ Button Click Logic

• submitButton.addActionListener(...)

  ➤ Adds an event listener to handle the click event on the Submit button.

• Inside the ActionListener:

  • agreeBox.isSelected()

    ➤ Checks if the user has agreed to the terms.

  • nameField.getText()

    ➤ Retrieves the name entered by the user.

  • male.isSelected() / female.isSelected()

    ➤ Checks which gender option is selected.

  • JOptionPane.showMessageDialog(...)

    ➤ Displays a popup showing the entered name and selected gender if terms are accepted.

    ➤ If the terms are not accepted, it shows a warning popup.

🖼️ Final Frame Configuration

• frame.setSize(350, 250);

  ➤ Sets the overall width and height of the frame.

• frame.setLayout(null);

  ➤ Disables layout managers; components are manually positioned.

• frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

  ➤ Exits the application when the window is closed.

• frame.setVisible(true);

  ➤ Makes the frame and its contents visible to the user.