Java Swing - W3spoint

Java Swing is a user interface (UI) toolkit for Java applications. It is a part of the Java Foundation Classes (JFC) and provides a rich set of GUI components for building desktop applications. Swing was developed to provide a more flexible and powerful set of GUI components than the earlier Abstract Window Toolkit (AWT).

Swing provides a wide variety of components, including buttons, labels, text fields, combo boxes, tables, trees, and many others. These components can be customized in terms of appearance and behavior to suit the needs of the application.

Swing is built on top of the Java AWT, and provides a platform-independent implementation of the GUI components. It also includes a comprehensive set of event handling mechanisms for responding to user input and other events.

Swing supports various layout managers to help developers create complex and dynamic layouts for their applications. It also provides support for internationalization and accessibility features.

Overall, Swing is a powerful and flexible UI toolkit that allows developers to create rich and interactive desktop applications in Java.

Difference between AWT and Swing:

AWT (Abstract Window Toolkit) and Swing are both Java GUI toolkits used for building desktop applications, but they differ in several key ways.

Architecture: AWT was the first GUI toolkit developed for Java, and it is built on top of the platform-specific native windowing system. In contrast, Swing is built entirely in Java and provides a platform-independent implementation of the GUI components.
Look and feel: AWT components use the platform-specific look and feel, which can vary depending on the operating system. Swing, on the other hand, provides a consistent look and feel across all platforms, which can be customized using pluggable look and feel (PLAF) classes.
Flexibility: AWT provides a limited set of GUI components, whereas Swing provides a wider variety of components that can be customized in terms of appearance and behavior. Swing also includes more advanced components such as JTree, JTable, and JEditorPane.
Layout management: AWT has a simpler layout management system, while Swing provides a more powerful and flexible system that can be used to create complex and dynamic layouts.
Performance: AWT has better performance than Swing since it uses native platform components. Swing, on the other hand, relies on Java code to implement the components, which can result in slower performance.

Overall, Swing is considered to be a more flexible and powerful GUI toolkit than AWT, although AWT may be a better choice for simple applications where performance is a critical concern.

What is JFC:

JFC stands for Java Foundation Classes, which is a collection of Java class libraries and APIs that are used for building desktop applications with rich graphical user interfaces (GUIs). The JFC includes two main components: Swing and the Abstract Window Toolkit (AWT).

Swing is a GUI toolkit that is built on top of AWT and provides a more flexible and powerful set of GUI components for building desktop applications. It includes a wide variety of components such as buttons, labels, text fields, combo boxes, tables, and trees, and provides a platform-independent implementation of these components.

AWT is the original GUI toolkit for Java and provides a set of native platform-specific components for building GUIs. It includes components such as buttons, checkboxes, and text fields, and relies on the underlying platform’s windowing system to render these components.

The JFC also includes other libraries such as Java 2D for advanced graphics and imaging, Java Sound for audio playback and capture, and Java Accessibility API for creating applications that are accessible to users with disabilities.

Overall, the JFC provides a comprehensive set of tools and APIs for building desktop applications with rich GUIs in Java.

Hierarchy of Java Swing classes:

Java Swing provides a hierarchical class structure to organize its GUI components. The class hierarchy is rooted at the java.awt.Component class, which is the base class for all Swing components. Here’s a brief overview of the Swing class hierarchy:

java.awt.Component: The base class for all Swing components.
- javax.swing.JComponent: A subclass of Component that provides a more powerful and flexible set of GUI components.
  - javax.swing.AbstractButton: A subclass of JComponent that provides a base class for all button-like components.
    - javax.swing.JButton: A subclass of AbstractButton that provides a simple button component.
    - javax.swing.JToggleButton: A subclass of AbstractButton that provides a toggle button component.
    - javax.swing.JCheckBox: A subclass of JToggleButton that provides a checkbox component.
    - javax.swing.JRadioButton: A subclass of JToggleButton that provides a radio button component.
  - javax.swing.JLabel: A subclass of JComponent that provides a component for displaying text or an image.
  - javax.swing.JTextField: A subclass of JComponent that provides a text input field.
  - javax.swing.JComboBox: A subclass of JComponent that provides a dropdown list of options.
  - javax.swing.JList: A subclass of JComponent that provides a list of items.
  - javax.swing.JSpinner: A subclass of JComponent that provides a spinner control for selecting numerical values.
  - javax.swing.JTable: A subclass of JComponent that provides a table component for displaying tabular data.
  - javax.swing.JTree: A subclass of JComponent that provides a tree component for displaying hierarchical data.
  - javax.swing.JToolBar: A subclass of JComponent that provides a toolbar component for grouping related controls.
  - javax.swing.JMenuBar: A subclass of JComponent that provides a menu bar component for displaying menus.
  - javax.swing.JMenu: A subclass of JComponent that provides a menu component for grouping related menu items.
  - javax.swing.JMenuItem: A subclass of JComponent that provides a menu item component.
  - javax.swing.JPopupMenu: A subclass of JComponent that provides a popup menu component.

This is not an exhaustive list, but it covers some of the most commonly used Swing components. The Swing class hierarchy is designed to be extensible, and developers can create their own custom components by subclassing JComponent or one of its subclasses.

Commonly used Methods of Component class:

The Component class is the base class for all Swing components in Java, and it provides a large number of methods for working with GUI components. Here are some commonly used methods of the Component class:

void setVisible(boolean visible): Sets the visibility of the component.
void setEnabled(boolean enabled): Sets the enabled state of the component.
void setSize(int width, int height): Sets the size of the component.
void setLocation(int x, int y): Sets the location of the component.
void setPreferredSize(Dimension preferredSize): Sets the preferred size of the component.
void setMinimumSize(Dimension minimumSize): Sets the minimum size of the component.
void setMaximumSize(Dimension maximumSize): Sets the maximum size of the component.
void setToolTipText(String text): Sets the tooltip text for the component.
void setBackground(Color color): Sets the background color of the component.
void setForeground(Color color): Sets the foreground color of the component.
void setFont(Font font): Sets the font used to display text in the component.
Dimension getSize(): Returns the current size of the component.
Point getLocation(): Returns the current location of the component.
String getName(): Returns the name of the component.
String getToolTipText(): Returns the tooltip text for the component.
Color getBackground(): Returns the current background color of the component.
Color getForeground(): Returns the current foreground color of the component.
Font getFont(): Returns the current font used to display text in the component.
void addMouseListener(MouseListener listener): Adds a MouseListener to the component.
void removeMouseListener(MouseListener listener): Removes a MouseListener from the component.

These are just a few examples of the methods available in the Component class. There are many more methods available for working with GUI components, depending on the specific needs of your application.

Java Swing Examples:

Here are some examples of Java Swing applications:

Calculator: A simple calculator application that performs basic arithmetic operations, such as addition, subtraction, multiplication, and division.
Notepad: A basic text editor application that allows users to create, edit, and save plain text documents.
Image Viewer: An application that allows users to view and manipulate images, such as resizing, rotating, and cropping.
File Explorer: An application that allows users to navigate and manage files and directories on their system.
Chat Application: A real-time chat application that allows users to communicate with each other over a network.
Music Player: An application that allows users to play and manage their music library.
Video Player: An application that allows users to play and manage their video library.
Drawing Application: An application that allows users to draw and create images using a variety of tools and shapes.
Paint Application: An application that allows users to create and edit images using a variety of painting tools.
Calendar: An application that allows users to view and manage their schedules and appointments.

These are just a few examples of the many types of applications that can be built using Java Swing. With its rich set of GUI components and easy-to-use API, Java Swing is a popular choice for building desktop applications in Java.

Simple Java Swing Example:

Here is a simple Java Swing example that creates a window with a label:

import javax.swing.*;

public class HelloWorldSwing {
    private static void createAndShowGUI() {
        //Create and set up the window
        JFrame frame = new JFrame("HelloWorldSwing");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Add the label
        JLabel label = new JLabel("Hello World");
        frame.getContentPane().add(label);

        //Display the window
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event dispatch thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

This code creates a JFrame window with a title “HelloWorldSwing” and sets the default close operation to JFrame.EXIT_ON_CLOSE. It then creates a JLabel with the text “Hello World” and adds it to the content pane of the JFrame. Finally, it packs and displays the window.

The main method schedules a job for the event dispatch thread to create and show the GUI. The event dispatch thread is responsible for handling all GUI events, such as mouse clicks and keyboard inputs, and updating the user interface accordingly. By using the SwingUtilities.invokeLater method, the code ensures that the GUI is created and shown on the event dispatch thread.

Example of Swing by Association inside constructor:

Here is an example of how Swing components can be created and associated with each other inside a constructor:

import javax.swing.*;

public class MyFrame extends JFrame {
    private JLabel label;
    private JButton button;

    public MyFrame() {
        super("My Frame");
        
        // Create a label with text "Hello, World!"
        label = new JLabel("Hello, World!");
        
        // Create a button with text "Click Me"
        button = new JButton("Click Me");
        
        // Associate the label with the button
        button.addActionListener(e -> {
            label.setText("Button Clicked!");
        });
        
        // Add the label and button to the frame's content pane
        getContentPane().add(label);
        getContentPane().add(button);

        // Set the frame properties
        setSize(300, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    }
    
    public static void main(String[] args) {
        MyFrame frame = new MyFrame();
    }
}

This code creates a JLabel with the text “Hello, World!” and a JButton with the text “Click Me” inside the constructor of the MyFrame class. It then associates the label with the button by adding an action listener to the button that changes the label’s text to “Button Clicked!” when the button is clicked.

The label and button variables are declared as instance variables of the MyFrame class, so they can be accessed and manipulated from within other methods of the class.

Finally, the label and button are added to the frame’s content pane using the getContentPane() method, and the frame’s properties are set before making it visible.

When the main method is called, a new instance of MyFrame is created and displayed.

Simple example of Swing by inheritance:

Here is a simple example of how Swing components can be created by inheritance:

import javax.swing.*;

public class MyFrame extends JFrame {
    private JLabel label;
    private JButton button;

    public MyFrame() {
        super("My Frame");
        
        // Create a label with text "Hello, World!"
        label = new JLabel("Hello, World!");
        
        // Create a button with text "Click Me"
        button = new JButton("Click Me");
        
        // Add the label and button to the frame's content pane
        getContentPane().add(label);
        getContentPane().add(button);
        
        // Set the frame properties
        setSize(300, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    }
    
    public static void main(String[] args) {
        MyFrame frame = new MyFrame();
    }
}

In this example, MyFrame class extends JFrame, so it inherits all the properties and methods of JFrame. In the constructor of MyFrame, it creates a JLabel with the text “Hello, World!” and a JButton with the text “Click Me”, and adds them to the frame’s content pane using the getContentPane() method.

The setSize(), setDefaultCloseOperation(), setLocationRelativeTo(), and setVisible() methods are called to set the frame properties and make it visible.

When the main method is called, a new instance of MyFrame is created and displayed.