In this article Components, Hierarchy, and Panes we give the information about Components, Hierarchy, and Panes are the major parts of creating GUI (Graphical User Interface) in Swing.
Components, Hierarchy, and Panes in Swing
Swing is an advanced version of AWT (Abstract Window Toolkit) that provides a richer set of GUI (Graphical User Interface) components. It is platform-independent, lightweight, and flexible, allowing developers to create modern and user-friendly interfaces.
1. Components in Swing
Components are the visible elements of a GUI through which users interact with an application.
All Swing components are subclasses of the JComponent class.
Common Swing Components
| Component | Description | Example |
| JButton | A clickable button used to perform an action. | JButton b = new JButton(“Click Me”); |
| JLabel | Displays static text or an image. | JLabel l = new JLabel(“Welcome to Swing”); |
| JTextField | Accepts text input from the user. | JTextField tf = new JTextField(20); |
| JCheckBox | Allows the user to select/deselect an option. | JCheckBox cb = new JCheckBox(“I Agree”); |
| JRadioButton | Used for mutually exclusive choices. | JRadioButton rb = new JRadioButton(“Male”); |
| JComboBox | A drop-down list of options. | JComboBox cb = new JComboBox(new String[]{“A”,”B”,”C”}); |
| JList | Displays a list of selectable items. | JList list = new JList(new String[]{“One”,”Two”}); |
Advantages of Swing Components
- Platform-Independent Look and Feel – Same appearance on all systems.
- Lightweight Components – Fully implemented in Java.
- Pluggable Look and Feel – Can change appearance dynamically.
2. Hierarchy of Swing Components
Swing follows a component hierarchy, meaning components are arranged within containers in a parent–child relationship.
Top-Level Containers
These act as the main windows that hold other components:
- JFrame – Main application window (with title bar, border, etc.).
- JDialog – Pop-up window for messages or user input.
- JApplet – Used to create applets that run in browsers or viewers.
Intermediate Containers
Used to group and organize components:
- JPanel – Basic container used to hold and manage multiple components.
Basic Components
Actual interface elements (like buttons, labels, etc.) placed inside panels or frames.
Example: Component Hierarchy
import javax.swing.*;
public class SwingHierarchyExample
{
public static void main(String[] args)
{
JFrame frame = new JFrame(“Swing Example”);
JPanel panel = new JPanel();
JButton button = new JButton(“Click Me”);
JLabel label = new JLabel(“Hello”);
panel.add(button);
panel.add(label);
frame.add(panel);
frame.setSize(300, 200);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Hierarchy: JFrame → JPanel → JButton/JLabel
3. Panes in Swing
Every Swing top-level container (like JFrame) contains multiple panes, which help in managing and displaying components efficiently.
Types of Panes
| Pane | Description | Example/Usage |
| Content Pane | The main area where components are added. | frame.getContentPane().add(new JButton(“Click Me”)); |
| Glass Pane | Transparent layer above all components; used for overlays or special effects. | Custom drawing or event tracking. |
| Layered Pane | Allows stacking components on different layers (Z-order). | JLayeredPane lets you overlap components. |
| Root Pane | Base pane that holds Content, Glass, and Layered panes. | Automatically managed by JFrame. |
Example: Glass Pane
frame.setGlassPane(new JPanel()
{
protected void paintComponent(Graphics g)
{
g.setColor(new Color(0, 0, 0, 50)); // Transparent overlay
g.fillRect(0, 0, getWidth(), getHeight());
}
});
frame.getGlassPane().setVisible(true);
4. Simple Swing Application Example
import javax.swing.*;
public class SimpleSwingApp
{
public static void main(String[] args)
{
JFrame frame = new JFrame(“Simple Swing Application”);
JButton button = new JButton(“Click Me”);
JPanel panel = new JPanel();
panel.add(button);
frame.add(panel);
frame.setSize(300, 200);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
5. Summary
| Concept | Description |
| Components | UI elements such as JButton, JLabel, JTextField, etc. derived from JComponent. |
| Hierarchy | Components are arranged in a structured order — top-level containers hold panels and basic components. |
| Panes | Help organize and manage components (Content, Glass, Layered, Root). |
Swing provides a modern, flexible, and lightweight framework for creating powerful and visually appealing desktop applications.
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