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What is Swing in Java?
What is Swing in Java?
Swing is a user interface toolkit that provides a rich set of user interface elements and allows for platform-independent GUI development.
What class in Swing is used to create a top-level window?
What class in Swing is used to create a top-level window?
JFrame
Which method is used to change the size of a JFrame?
Which method is used to change the size of a JFrame?
Swing components are configured on the event dispatch thread.
Swing components are configured on the event dispatch thread.
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How do you set the JFrame to be not resizable?
How do you set the JFrame to be not resizable?
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The command to set the default close operation for a JFrame to exit the application is: frame.setDefaultCloseOperation(JFrame.___);
The command to set the default close operation for a JFrame to exit the application is: frame.setDefaultCloseOperation(JFrame.___);
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What does the setLocation(int x, int y) method do in JFrame?
What does the setLocation(int x, int y) method do in JFrame?
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Which class is used to draw graphics in Java 2D?
Which class is used to draw graphics in Java 2D?
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Match the following methods to their descriptions:
Match the following methods to their descriptions:
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To display an image in a JFrame, use the command: frame.setIconImage(new ImageIcon("______").getImage());
To display an image in a JFrame, use the command: frame.setIconImage(new ImageIcon("______").getImage());
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How do you construct an ellipse in Java?
How do you construct an ellipse in Java?
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What method is used to select a color in the Graphics2D class?
What method is used to select a color in the Graphics2D class?
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Which class defines standard colors such as BLACK, RED, and GREEN?
Which class defines standard colors such as BLACK, RED, and GREEN?
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The Color constructor allows RGB values from 0 to 255.
The Color constructor allows RGB values from 0 to 255.
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How can you fill a shape with color?
How can you fill a shape with color?
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What is the purpose of the getAvailableFontFamilyNames method?
What is the purpose of the getAvailableFontFamilyNames method?
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What methods does the MenuListener interface define?
What methods does the MenuListener interface define?
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The method used to obtain the string bounds is called getString____.
The method used to obtain the string bounds is called getString____.
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What action does the menuSelected method perform when the Read Only checkbox menu item is selected?
What action does the menuSelected method perform when the Read Only checkbox menu item is selected?
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Match the following classes with their descriptions:
Match the following classes with their descriptions:
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How do you create a toolbar in Swing?
How do you create a toolbar in Swing?
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What is the function of the JPanel class?
What is the function of the JPanel class?
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What does the second parameter of the JTextField constructor set?
What does the second parameter of the JTextField constructor set?
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How do you structure a Font object?
How do you structure a Font object?
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How do you change the text of a JTextField?
How do you change the text of a JTextField?
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What method is used to add a button to a JToolBar?
What method is used to add a button to a JToolBar?
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Which layout manager makes components fill the available space?
Which layout manager makes components fill the available space?
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By default, toolbars in Swing are vertical.
By default, toolbars in Swing are vertical.
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What class does Swing provide for password fields?
What class does Swing provide for password fields?
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What method do you use to enable line wrapping in a JTextArea?
What method do you use to enable line wrapping in a JTextArea?
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What method is used to set a tooltip text for a button in Swing?
What method is used to set a tooltip text for a button in Swing?
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What is a disadvantage of toolbars?
What is a disadvantage of toolbars?
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What is a ButtonGroup responsible for?
What is a ButtonGroup responsible for?
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How can you specify a title for a JToolBar?
How can you specify a title for a JToolBar?
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How can you create a combo box in Swing?
How can you create a combo box in Swing?
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What constant is used to create a vertical JToolBar?
What constant is used to create a vertical JToolBar?
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What method adds a new item to a JComboBox?
What method adds a new item to a JComboBox?
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What constructor should be used to create a JSlider?
What constructor should be used to create a JSlider?
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What does the setEnabled method do for a menu item?
What does the setEnabled method do for a menu item?
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Which of the following methods are used to create menus in Swing? (Select all that apply)
Which of the following methods are used to create menus in Swing? (Select all that apply)
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A JCheckBox can hold multiple selection states.
A JCheckBox can hold multiple selection states.
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You can add icons to menu items in Swing.
You can add icons to menu items in Swing.
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What is the purpose of adding an action listener to menu items?
What is the purpose of adding an action listener to menu items?
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Study Notes
Graphics Programming Overview
- Introduces Java graphical user interfaces (GUIs), focusing on window creation, frame positioning, text display, and image handling.
Introducing Swing
- Swing is an extension to Java 1.1, included in Java SE 1.2, providing a robust GUI toolkit.
- Developed to address the limitations of AWT which often led to platform-specific bugs.
- Swing components are not peer-based; they use Java's code to render UI elements, resulting in portability ("Write Once, Run Anywhere").
- Provides a consistent user experience across platforms but may differ visually from native controls.
Creating a Frame
- JFrame serves as a top-level window in Swing, extending the AWT Frame class, and supports JFC/SWING component architecture.
- Multiple constructors available for JFrame allows for flexibility in creation:
- Invisible frame, frame with a title, frame with specific graphics configurations.
- Set frame dimensions and visibility using
JFrame.setSize(width, height)
andJFrame.setVisible(true)
. - Frame resizing can be toggled using
JFrame.setResizable(true/false)
, controlling user resizing options. - Position frames on screen using
JFrame.setLocation(x, y)
with (0, 0) being the top-left corner. - Closing behavior can be managed with
JFrame.setDefaultCloseOperation(int)
, with options for exiting or disposing.
Positioning a Frame
- Key methods for positioning and customizing frames:
-
setLocation(int x, int y)
andsetBounds(int x, int y, int width, int height)
to specify location and size. -
setIconImage(Image img)
for the title bar icon andsetTitle(String title)
for frame text.
-
Frame Properties
- Getter/setter methods implement properties for frame customization, like
getTitle()
andsetTitle(String title)
.
Determining a Good Frame Size
- Use
Toolkit.getDefaultToolkit().getScreenSize()
to obtain screen dimensions. - Ideal frame size often set to 50% of screen size, positioning automatically can be done with
setLocationByPlatform(true)
. -
ImageIcon
class simplifies image loading for icons. -
frame.setExtendedState(Frame.MAXIMIZED_BOTH)
to maximize the frame.
Displaying Information in a Component
- Information is displayed within a frame by adding components to the content pane via
Container contentPane = frame.getContentPane()
. - Custom components extend
JComponent
, requiring implementation ofpaintComponent(Graphics g)
for custom painting. - Use
g.drawString(text, x, y)
for text display; overridegetPreferredSize
for suggested component dimensions.
Working with 2D Shapes
- Java 2D library offers advanced shape drawing capabilities, requiring a
Graphics2D
object for drawing operations. - Uses Object-Oriented principles organizing shapes like
Line2D
,Rectangle2D
,Ellipse2D
and providing aShape
interface. - Includes methods to create shapes (e.g.,
Graphics2D.draw(shape)
) with appropriate casting for type consistency. - For rectangles, use
setFrameFromDiagonal(p1, p2)
and for ellipses,setFrameFromCenter(center, width, height)
.
Using Color
-
Graphics2D.setPaint(Color)
to select drawing colors andfill
method to paint closed shapes. - Java's
Color
class provides predefined constants for common colors and allows custom colors through RGB values. - Backgrounds and foregrounds for components are set using
setBackground(Color)
andsetForeground(Color)
methods.### System Colors and Fonts - Use
p.setBackground(SystemColor.window)
to set the default window color. - The available system color names and their meanings are listed in a specific table (Table 10.1).
- To discover available fonts, use the
getAvailableFontFamilyNames
method from theGraphicsEnvironment
class. - Create font objects using the
Font
class, specifying face name, style, and size:Font sansbold14 = new Font("SansSerif", Font.BOLD, 14);
. - Font styles include
Font.PLAIN
,Font.BOLD
,Font.ITALIC
, andFont.BOLD + Font.ITALIC
.
Font Handling
- Load font files in various formats like TrueType, OpenType, or PostScript using an input stream.
- To create a font from a file, use:
Font f1 = Font.createFont(Font.TRUETYPE_FONT, in);
- Adjust font size with
deriveFont
:Font f = f1.deriveFont(14.0F);
.
String Measurement and Rendering
- Measure string dimensions with
getStringBounds
andgetFontRenderContext
fromGraphics2D
. - Obtain the width, height, and ascent of a string using
Rectangle2D bounds
. -
getLineMetrics
provides descent and leading information.
Image Display
- Load images using
ImageIcon
and display with thedrawImage
method. - Tiling images across a window can be achieved by drawing and copying areas in the
paintComponent
method.
Java Adapter Classes
- Java provides adapter classes to simplify listener interface implementation:
-
WindowAdapter
forWindowListener
-
KeyAdapter
forKeyListener
-
MouseAdapter
forMouseListener
-
MouseMotionAdapter
forMouseMotionListener
-
FocusAdapter
forFocusListener
-
ComponentAdapter
forComponentListener
-
ContainerAdapter
forContainerListener
-
Model-View-Controller (MVC) Design Pattern
- MVC is integral to designing the Swing framework:
- Model: Stores content/state (e.g., ButtonModel).
- View: Displays content (e.g., button appearance).
- Controller: Handles user input events.
Layout Management
- Components are placed in containers managed by layout managers.
- Default layout managers include:
- BorderLayout: Positions components in five areas (N, S, E, W, CENTER).
- GridLayout: Arranges components in a grid with equal cell sizes.
Text Input Components
- JTextField: Accepts a single line of text.
-
JTextArea: Accepts multiple lines, can be wrapped with
setLineWrap(true)
. - JPasswordField: Masks user input with asterisks.
- JScrollPane: Enables scrollable views for text components.
Choice Components
-
Checkboxes: Represent binary choices (
JCheckBox
). UsesetSelected()
to manage state. -
Radio Buttons: Are exclusive selections, grouped for mutual exclusivity. Managed by a
ButtonGroup
.
Event Handling
- Attach listeners to components (e.g., ActionListeners to buttons) to define behaviors based on user actions.
- Retrieve states of components (e.g., selected state of checkboxes) to change component properties dynamically.### Button Group and Action Listener
- Create a
ButtonGroup
to groupJRadioButton
components, allowing only one button to be selected at a time. - Each button can be created with an initial selection state, e.g.,
mediumButton
initially selected. - Utilize
ActionListener
to handle button actions by setting the font size based on the selected radio button. - Prefer separate action listeners for buttons to tightly couple size values to specific buttons rather than a single listener managing all conditions.
Borders in Swing
- Borders visually separate components in user interfaces, useful for grouping sets of radio buttons.
- Create borders using
BorderFactory
methods, selecting from styles like Lowered Bevel, Raised Bevel, or Etched. - A title can be added to borders using
BorderFactory.createTitledBorder
. - Combine multiple borders by calling
BorderFactory.createCompoundBorder
. - Apply a border to a component using
setBorder
method ofJComponent
.
Combo Boxes
- Use
JComboBox
when multiple options are available, allowing for compact display compared to radio buttons. - Make the combo box editable with
setEditable
to permit text entry in addition to selection. - Add items to a combo box with
addItem
, and useinsertItemAt
to place items at specific positions. - Remove items dynamically with
removeItem
orremoveItemAt
, and clear all items withremoveAllItems
. - Handle selections with an
ActionListener
to update the UI based on the selected item.
Sliders
-
JSlider
allows selection from a continuous range of numbers, with parameters for min, max, and initial values. - Vertical sliders can be created with the
SwingConstants.VERTICAL
parameter. - Configure tick mark spacing with
setMajorTickSpacing
andsetMinorTickSpacing
, with visible tick marks enabled bysetPaintTicks
. - Attach labels to tick marks using a
Hashtable
for clear value representation. - Customize slider appearance by enabling/disabling track display with
setPaintTrack
and adjusting direction withsetInverted
.
Menus
- Menus provide an organized way to access application commands, typically implemented with a
JMenuBar
. - Construct menus by creating
JMenu
objects and adding them to the menu bar; populate menus withJMenuItem
. - Use
ActionListener
to handle actions for each menu item, providing interactivity when items are selected. - Create class-based action handlers using
AbstractAction
for tailored behavior linking to menu items.
Icons in Menu Items
- Menu items can have icons using constructors that accept
Icon
, similar to buttons. - Use
setHorizontalTextPosition
to manage the positioning of text relative to icons.
Checkbox and Radio Button Menu Items
- Implement checkbox items with
JCheckBoxMenuItem
, allowing toggled states. - Group radio button menu items using
ButtonGroup
to ensure one selection at a time.
Pop-Up Menus
- Create floating menus with
JPopupMenu
, without requiring a title. - Use
setComponentPopupMenu
for attaching pop-up menus to components, enabling context-sensitive interactions.
Keyboard Shortcuts and Mnemonics
- Enhance usability by implementing keyboard mnemonics, which are easily specified when creating
JMenuItem
. - Connect keyboard accelerators (e.g., Ctrl+O) to menu items with
setAccelerator
.
Enabling/Disabling Menu Items
- Control menu item availability with
setEnabled
, making it context-sensitive. - Monitor menu events using
MenuListener
to dynamically enable/disable items based on conditions.
Toolbars
- Toolbars provide a user-friendly interface for common commands, implemented with
JToolBar
. - Populate toolbars with buttons or Action objects, and organize groups using separators.
Tooltips
- Add informative tooltips to components using
setToolTipText
for improved user guidance. - Associate tooltips using the
Action.SHORT_DESCRIPTION
key for actions representing buttons.
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