Custom GUI Components

Creating custom GUI components in Swing allows you to extend the functionality of existing components or build entirely new components tailored to your application's specific needs. Custom components can enhance the user interface and provide unique features not available in standard Swing components. Here's how you can create custom GUI components in Swing:

Extending Existing Components

You can create custom components by extending existing Swing classes and overriding their methods to provide custom behavior or appearance.

Example: Custom JButton with Customized Appearance

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

public class CustomButton extends JButton {

    public CustomButton(String text) {
        super(text);
        setForeground(Color.RED);
        setBackground(Color.WHITE);
        setBorder(BorderFactory.createLineBorder(Color.BLUE));
        setFont(new Font("Arial", Font.BOLD, 12));
    }
}

In this example, `CustomButton` extends `JButton` and customizes its appearance by setting the foreground color, background color, border, and font.

Creating Composite Components

Composite components are made up of multiple existing Swing components arranged together to create a new component with unique functionality.

Example: Custom PasswordField with Show/Hide Password Button

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

public class PasswordFieldWithButton extends JPanel {

    private JPasswordField passwordField;
    private JButton showHideButton;

    public PasswordFieldWithButton() {
        setLayout(new BorderLayout());

        passwordField = new JPasswordField();
        add(passwordField, BorderLayout.CENTER);

        showHideButton = new JButton("Show");
        showHideButton.addActionListener(e -> togglePasswordVisibility());
        add(showHideButton, BorderLayout.EAST);
    }

    private void togglePasswordVisibility() {
        if (passwordField.getEchoChar() == '\u2022') {
            passwordField.setEchoChar((char) 0);
            showHideButton.setText("Hide");
        } else {
            passwordField.setEchoChar('\u2022');
            showHideButton.setText("Show");
        }
    }
}

In this example, `PasswordFieldWithButton` extends `JPanel` and contains a `JPasswordField` for entering passwords and a `JButton` for toggling password visibility.

Custom Painting

You can perform custom painting by subclassing `JComponent` and overriding its `paintComponent()` method to draw custom graphics or render custom content.

Example: Custom Painted Circle Component

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

public class CircleComponent extends JComponent {

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        int centerX = getWidth() / 2;
        int centerY = getHeight() / 2;
        int radius = Math.min(getWidth(), getHeight()) / 2;
        g.setColor(Color.RED);
        g.fillOval(centerX - radius, centerY - radius, 2 * radius, 2 * radius);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(100, 100);
    }
}

In this example, `CircleComponent` extends `JComponent` and overrides its `paintComponent()` method to draw a red circle at the center of the component.

Conclusion

Creating custom GUI components in Swing allows you to extend the functionality and appearance of existing components or build entirely new components from scratch. Whether you're customizing the appearance of standard components, creating composite components, or performing custom painting, Swing provides the flexibility and extensibility to create rich and interactive user interfaces tailored to your application's requirements.