Java GUI: AWT and Swing

• GUI stands for Graphical User Interface.
• GUI is a visual representation of communication for easy machine interaction.
• GUI includes graphical representations like buttons and icons for communication.
• Program interface uses computer graphics to simplify usage.
• GUI was designed in 1970 at Xerox Corporation's Palo Alto Research Center
• Basic GUI components: Pointer, Pointing device, Icons, Desktop, Windows, Menu.

Java AWT

• It is a platform-independent windowing, graphics, and user-interface widget toolkit.
• It is part of the Java Foundation Classes (JFC)
• It is Standard API for graphical user interfaces in Java
• AWT contains fundamental classes for constructing GUIs.

Java GUI

• Java provides a set of libraries for platform-independent GUI creation.
• JFC encompasses features for building GUIs, adding graphics, and interactivity.
• GUI programs are implemented using javax.swing (Swing classes) and java.awt (AWT classes).
• All GUI classes are based on the Application Windowing Toolkit or AWT.

Java Swing

• Swing is a graphical user interface toolkit in Java and a part of the Java Foundation Classes (JFC).
• Swing includes GUI widgets like text boxes, buttons, split-panes, and tables and runs on all platforms.
• Swing supports pluggable look and feel by emulating native platform facilities.
• Swing classes are lightweight because they don't require allocation of native OS resources.

AWT vs Swing

• AWT is platform dependent while Swing is platform independent.
• AWT classes are heavyweight, Swing classes are lightweight.
• AWT does not follow MVC, while Swing follows MVC.
• AWT has lesser components than swing, which has more powerful components.
• AWT doesn't support pluggable look and feel; Swing supports pluggable look and feel.

Container Class

• Any class with other components is a container class
• At least one container class is needed for building GUI applications.
• Panel is used to organize components on a window.
• Frame is a fully functioning window with icons and titles.
• Dialog is like a pop-up window, but less functional than a frame.

Core aspects of User Interface

• UI Elements: Core visual elements users see and interact with.
• Layouts: Define how UI elements are organized, providing the GUI's look and feel.
• Behavior: The are events occurring when user interacts with UI elements.

GUI Components: Frames

• Frames are windows with a title bar, menu bar, maximize, minimize, and close buttons.
• Use a superclass constructor to set frame title and other settings.
• Set frame window size by specifying width and height in pixels.
• Decide the action when the user closes the window and display the frame.
• JFrame class constructors: JFrame() and JFrame(String).
• JFrame(String) sets the frame's title, setTitle(String) method can also set the title.
• Frame size is established using setSize(int, int) with width and height arguments.
• pack() method resizes frame based on size of contained components.
• Frames are invisible when created; setVisible(boolean) makes them visible.
• By default, a displayed frame is positioned in the upper-left corner of the desktop.
• setBounds(int, int, int, int) method specifies the (x, y) position of the frame's upper-left corner on the desktop and also sets the width and height of the frame.
• setDefaultCloseOperation() method is used to set the action when a frame is closed.
• EXIT_ON_CLOSE exits the application.
• DISPOSE_ON_CLOSE closes the frame and removes it from memory.
• DO_NOTHING_ON_CLOSE keeps the frame open.
• HIDE_ON_CLOSE closes the frame and continues running.
• Component: Abstract base class for non-menu user-interface controls of SWING.
• Component: Represents an object with graphical representation.
• Container: Interface elements that can hold other components.
• Container: It is a component that can contain other SWING components.
• JComponent: Base class for all Swing UI components. A swing component inheriting from JComponent must be in a containment hierarchy with a top-level Swing container.
• JLabel: Text or graphics providing information. A JLabel object is a component for placing text in a container.
• To create a label, use:
• JLabel(String): Label with specified text.
• JLabel(String, int): Label with specified text and alignment.
• JLabel(String, Icon, int): Label with text, icon, and alignment.
• JButton: Clickable regions with text or graphics indicating their purpose. Creates a labeled button.
• Constructors for buttons:
• JButton(String): Button labeled with specified text.
• JButton(Icon): Button displaying a graphical icon.
• JButton(String, Icon): Button has specified text and graphical icon.
• JTextField: Windows that accept and allow for edit of keyboard input.
• Text field is location where a user can enter/modify using a keyboard.
• Constructors include:
• JTextField(): An empty text field.
• JTextField(int): Text field with specified width.
• JTextField(String, int): Text field with specified text and width.
• Password fields hide characters typed; represented by JPasswordField class (subclass of JTextField).
• JPasswordField constructor methods take same arguments as parent class. Use setEchoChar(char) to obscure input.
• JTextArea: Text areas are editable and allow for more than one line of input.
• Constructor: JTextArea (String, int, int)—Text area with specified text, rows, and columns.
• setLineWrap(boolean) determines if text wraps to next line (true).
• setWrapStyleWord(boolean) sets wrap to word (true) or character (false).
• JScrollPane: Swing supports scrollbars through JScrollPane container for holding scrollable components.
• A scrolling pane is associated with a component in the pane's constructors
• JScrollPane(Component) —A scrolling pane that contains the specified component
• JScrollPane(Component, int, int) —A scrolling pane with the specified component, vertical scrollbar configuration, and horizontal scrollbar configuration
• Scrollbars are configured using static class variables of the ScrollPaneConstants interface.
• for vertical scrollbars:
• VERTICAL_SCROLLBAR_ALWAYS
• VERTICAL_SCROLLBAR_AS_NEEDED
• VERTICAL_SCROLLBAR_NEVER
• JColorChooser provides a pane of controls designed to allow a user to manipulate and select a color.
• Check boxes and radio buttons: Small squares (check boxes) or circles (radio buttons) for selection.
• Check boxes (JCheckBox class) display a check mark when selected, nothing otherwise.
• Radio buttons (JRadioButton class) appear as circles with a dot when selected, empty otherwise.
• JCheck Box: Graphical component in either true (on) or false (off) state.
• The following constructors are available for the JCheckBox class:
• JCheckBox(String) — A check box with the specified text label
• JCheckBox(String, boolean) — A check box with the specified text label that is selected if the second argument is true
• JCheckBox(Icon) - A check box with the specified graphical icon
• JCheckBox(Icon, boolean) -A check box with the specified graphical icon that is selected if the second argument is true
• JCheckBox(String, Icon) A check box with the specified text label and graphical icon
• JCheckBox(String, Icon, boolean)-A check box with the specified text label and graphical icon that is selected if the third argument is true
• JRadioButton: A graphical component in either true (on) or false (off) state in a group.
• To organize several radio buttons into a group, allowing only one to be selected at a time, create a ButtonGroup class object, as demonstrated in the following statement:
  • ButtonGroup choice = new ButtonGroup();
• The ButtonGroup object keeps track of all radio buttons in its group. Call the group’s add(Component) method to add the specified component to the group.
• Drop-down lists: Groups of related items that can be selected from drop-down menus or scrolling windows

Combo Boxes

• Swing class JComboBox creates combo boxes that present a drop-down menu for single value selection.

Steps to Create a Combo Box:

• Create a default JComboBox
• Add items using comboBox.addItem(Object)

Lists

• Lists can be created and filled with the contents of an array or a vector.

Constructors:

• JList(): Create an empty list.
• JList(Object[]): Create list containing specified class array (like String).
• JList(Vector): Create list containing java.util.Vector object.

Swing Layout

• Layout: Arrangement of components within the container.
• A layout manager determines how components will be arranged when they are added to a container.

Layouts

• BorderLayout: Arranges components in five regions: east, west, north, south, center.
• CardLayout: Treats components as cards; only one is visible at a time.
• FlowLayout: Default layout; arranges components in a directional flow.
• GridLayout: Manages components in a rectangular grid.
• GridBagLayout: Most flexible; aligns components vertically, horizontally, or along their baseline.
• GroupLayout: Hierarchically groups components to position them in a container.
• SpringLayout: Positions children of a container according to constraints.

Commonly Used Static Methods for JOptionPane Dialogs:

• showConfirmDialog: Asks a confirming question (yes/no/cancel).
• showInputDialog: Prompts for input, with text field or combo-box style list and OK/CANCEL buttons.
• showMessageDialog: Informs user, allows for a message and an OK button
• showOptionDialog: Grand unification, allows control over buttons' text choices.

Option Type

• DEFAULT_OPTION
• YES_NO_OPTION
• YES_NO_CANCEL_OPTION
• OK_CANCEL_OPTION