slide4.1_2009_r1 - Module Module 4.1 GUI Basics...

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Unformatted text preview: Module Module 4.1 GUI Basics EE3206/EE5805 Java Programming & Applications 1 Intended Intended Learning Outcomes To To distinguish simple GUI components. To To describe the Java GUI API hierarchy. To To create user interfaces using frames, panels, and simple UI components. To To understand the role of layout managers. To To use the FlowLayout, GridLayout, and BorderLayout managers to layout FlowLayout GridLayout BorderLayout components components in a container. To To specify colors and fonts using the Color and Font classes. To To use JPanel as subcontainers. EE3206/EE5805 Java Programming & Applications 2 Creating Creating GUI Objects // Create a button with text OK JButton jbtOK = new JButton("OK"); // Create a label with text "Enter your name: " JLabel jlblName = new JLabel("Enter your name: "); // Create a text field with text "Type Name Here" JTextField jtfName = new JTextField("Type Name Here"); // Create a check box with text bold JCheckBox jchkBold = new JCheckBox("Bold"); // Create a radio button with text red JRadioButton jrbRed = new JRadioButton("Red"); // Create a combo box with choices red, green, and blue JComboBox jcboColor = new JComboBox(new String{"Red", "Green", "Blue"}); Label Text field Check Box Radio Button Combo Box Button EE3206/EE5805 Java Programming & Applications 3 AWT AWT and Swing When When Java was introduced, the GUI classes were bundled in a library known as the Abstract Windows Toolkit (AWT). For every platform on which Java runs, the AWT (AWT). components are automatically mapped to the platform-specific components through platformtheir respective agents, known as peers. AWT AWT is fine for developing simple graphical user interfaces, but not for developing comprehensive GUI projects. Besides, Besides, AWT is prone to platform-specific bugs because its peer-based approach platformpeerrelies heavily on the underlying platform. With With the release of Java 2, the AWT user-interface components were replaced by a usermore robust, versatile, and flexible library known as Swing components. components. Swing Swing components are painted directly on canvases using Java code, except for components that are the subclasses of java.awt.Window or java.awt.Panel, which must be drawn using native GUI on a specific platform. Swing Swing components are less dependent on the target platform and use less of the native GUI resource. For this reason, Swing components that don’t rely on native GUI are referred to as lightweight components, and AWT components are referred to as components, heavyweight components. components. EE3206/EE5805 Java Programming & Applications 4 Heavyweight Heavyweight (AWT) vs. Lightweight (Swing) Dimension Font FontMetrics Object Color Graphics Component * LayoutManager 1 Classes in the java.awt package Heavyweight Panel Applet JApplet Container Window Frame Dialog JFrame JDialog JComponent Swing Components in the javax.swing package Lightweight EE3206/EE5805 Java Programming & Applications 5 GUI GUI Container Classes Dimension Font FontMetrics Object Color Graphics Component * LayoutManager 1 Classes in the java.awt package 1. Container classes can contain other GUI components. 2. Top-level Swing containers such as JFrame, JDialog, and JApplet -- are specialized components that provide a place for other Swing components to paint themselves. Panel Applet JApplet Container Window Frame Dialog JFrame JDialog JComponent Lightweight JPanel Heavyweight Swing Components in the javax.swing package 3. JComponent is the base class for all Swing components except top-level containers. To use a component that inherits from JComponent, you must place the component in a containment hierarchy whose root is a top-level Swing container. EE3206/EE5805 Java Programming & Applications 6 GUI GUI Helper Classes Dimension Font FontMetrics Object Color Graphics Component * LayoutManager 1 Classes in the java.awt package Heavyweight Panel Applet JApplet Container Window Frame Dialog JFrame JDialog JComponent 4. The helper classes are not subclasses of Component. They are used to describe the properties of GUI components such as graphics context, colors, fonts, and dimension. Lightweight JPanel Swing Components in the javax.swing package EE3206/EE5805 Java Programming & Applications 7 Swing Swing GUI Components JCheckBoxMenuItem JMenuItem JMenu JRadioButtonMenuItem JCheckBox JRadioButton AbstractButton JButton JToggleButton JComponent JTextComponent JEditorPane JTextField JTextArea JPasswordField JLabel JList JComboBox JSplitPane JPanel JOptionPane JSeparator JFileChooser JScrollBar JScrollPane JColorChooser JSlider JRootPane JToolTip JTabbedPane JToolBar JTree JLayeredPane JPopupMenu JMenuBar JTable JTableHeader JInternalFrame JProgressBar JSpinner EE3206/EE5805 Java Programming & Applications 8 AWT AWT (Optional) AWTEvent Font FontMetrics Object Color Graphics Component Container Button Label TextComponent Panel Window Applet Frame Dialog FileDialog TextField List Choice CheckBox TextArea LayoutManager CheckBoxGroup Canvas MenuComponent MenuItem MenuBar Menu Scrollbar EE3206/EE5805 Java Programming & Applications 9 Frames Frames and JFrame Class Frame Frame is a window that is not contained inside another window. Frame Frame is the basis to contain other user interface components in Java GUI applications. For For Swing GUI programs, use JFrame class to create widows. javax.swing.JFrame +JFrame() +JFrame(title: String) +setSize(width: int, height: int): void +setLocation(x: int, y: int): void +setVisible(visible: boolean): void +setDefaultCloseOperation(mode: int): void +setLocationRelativeTo (c: Component): void Creates a default frame with no title. Creates a frame with the specified title. Specifies the size of the frame. Specifies the upper-left corner location of the frame. Sets true to display the frame. Specifies the operation when the frame is closed. Sets the location of the frame relative to the specified component. If the component is null, the frame is centered on the screen. EE3206/EE5805 Java Programming & Applications 10 Creating Creating Frames import javax.swing.*; public class MyFrame { MyFrame public static void main(String args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(400, 300); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } } To add a button into the frame frame.add(new JButton("OK")); MyFrameWithComponents EE3206/EE5805 Java Programming & Applications 11 Layout Layout Managers Java Java’s layout managers provide a level of abstraction to automatically map your user interface on all window systems. systems. The The UI components are placed in containers. Each container has a layout manager to arrange the UI components within the container. Layout Layout managers are set in containers using the setLayout(LayoutManager) setLayout(LayoutManager) method in a container. Three Three simple Layout Managers FlowLayout FlowLayout GridLayout GridLayout BorderLayout BorderLayout EE3206/EE5805 Java Programming & Applications 12 FlowLayout FlowLayout Example java.awt.FlowLayout -alignment: int -hgap: int -vgap: int +FlowLayout() +FlowLayout(alignment: int) +FlowLayout(alignment: int, hgap: int, vgap: int) The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity. The alignment of this layout manager (default: CENTER). The horizontal gap of this layout manager (default: 5 pixels). The vertical gap of this layout manager (default: 5 pixels). Creates a default FlowLayout manager. Creates a FlowLayout manager with a specified alignment. Creates a FlowLayout manager with a specified alignment, horizontal gap, and vertical gap. Write a program that adds three labels and text fields into the content pane of a frame with a FlowLayout manager. ShowFlowLayout EE3206/EE5805 Java Programming & Applications Run 13 GridLayout GridLayout Example java.awt.GridLayout -rows: int -columns: int -hgap: int -vgap: int +GridLayout() The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity. The number of rows in this layout manager (default: 1). The number of columns in this layout manager (default: 1). The horizontal gap of this layout manager (default: 0). The vertical gap of this layout manager (default: 0). Creates a default GridLayout manager. +GridLayout(rows: int, columns: int) Creates a GridLayout with a specified number of rows and columns. +GridLayout(rows: int, columns: int, Creates a GridLayout manager with a specified number of rows and hgap: int, vgap: int) columns, horizontal gap, and vertical gap. Rewrite the program in the preceding example using a GridLayout manager instead of a FlowLayout manager to display the labels and text fields. ShowGridLayout EE3206/EE5805 Java Programming & Applications Run 14 The BorderLayout The BorderLayout Manager The BorderLayout manager divides the container into five areas: East, South, BorderLayout West, North, and Center. Components are added to a BorderLayout by using Center. BorderLayout the add method. add(Component, constraint); constraint) where constraint is constraint BorderLayout.EAST BorderLayout.SOUTH BorderLayout.EAST, BorderLayout.SOUTH, BorderLayout.WEST BorderLayout.NORTH BorderLayout.WEST, BorderLayout.NORTH, or BorderLayout.CENTER BorderLayout.CENTER. The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity. The horizontal gap of this layout manager (default: 0). The vertical gap of this layout manager (default: 0). Creates a default BorderLayout manager. java.awt.BorderLayout -hgap: int -vgap: int +BorderLayout() +BorderLayout(hgap: int, vgap: int) Creates a BorderLayout manager with a specified number of horizontal gap, and vertical gap. EE3206/EE5805 Java Programming & Applications 15 BorderLayout BorderLayout Example ShowBorderLayout Run 16 EE3206/EE5805 Java Programming & Applications The Color The Color Class You You can set colors for GUI components by using the java.awt.Color class. Colors are made of red, green, and blue components, each of which is represented by a byte value that describes its intensity, ranging from 0 (darkest shade) to 255 (lightest shade). This is known as the RGB model. RGB Color Color c = new Color(r, g, b); r, g, and b specify a color by its red, green, and blue components. Example: Color c = new Color(228, 100, 255); Color(228, 100, 255) EE3206/EE5805 Java Programming & Applications 17 Standard Standard Colors There There are thirteen standard color constants: BLACK BLACK, BLUE, CYAN, DARK_GRAY, GRAY, GREEN, LIGHT_GRAY, MAGENTA, ORANGE, PINK, RED, WHITE, and YELLOW. You You can use these two methods to set the component’s background and foreground colors: setBackground(Color setBackground(Color c) setForeground setForeground(Color c) Example: // jbt is an instance of JButton jbt jbt.setBackground(Color.YELLOW); jbt.setBackground(Color.YELLOW); jbt.setBackground(Color.LIGHT_GRAY); jbt.setBackground(Color.LIGHT_GRAY); EE3206/EE5805 Java Programming & Applications 18 The Font The Font Class Font Font Names Standard font names that are supported in all platforms are: SansSerif, Serif, Monospaced, Dialog, or DialogInput. Font Font Style Font.PLAIN, Font.BOLD, Font.ITALIC Font myFont = new Font(name, style, size); Example: Font myFont = new Font("SansSerif", Font.BOLD, 16); Font myFont = new Font("Serif", Font.BOLD|Font.ITALIC, 12); JButton jbtOK = new JButton("OK"); jbtOK.setFont(myFont); EE3206/EE5805 Java Programming & Applications a bitwise union 19 Using Using Panels as Sub-Containers SubPanels Panels act as sub-containers for grouping user interface components. subIt is recommended that you place the user interface components in panels and It place the panels in a frame. You can also place panels in a panel. Decompose Decompose into manageable sub-interface subEasy Easy for management You You can use new JPanel() to create a panel with a default FlowLayout manager or new JPanel default FlowLayout new JPanel( new JPanel(LayoutManager layout) to create a panel with the specified layout manager. Use Use the add(Component) method to add a component to the panel. For example, JPanel p = new JPanel(); JPanel(); p.add(new JButton("OK")); p.add(new JButton("OK")); EE3206/EE5805 Java Programming & Applications 20 // FlowLayout by default Testing Testing Panels Example This example uses panels to organize components. The program creates a user interface for a Microwave oven. frame A textfield p2 A button 12 buttons p1 TestPanels Run EE3206/EE5805 Java Programming & Applications 21 Common Common Features of Swing Components java.awt.Component -font: java.awt.Font -background: java.awt.Color -foreground: java.awt.Color -preferredSize: Dimension -visible: boolean +getWidth(): int +getHeight(): int +getX(): int +getY(): int The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity. The font of this component. The background color of this component. The foreground color of this component. The preferred size of this component. Indicates whether this component is visible. Returns the width of this component. Returns the height of this component. getX() and getY() return the coordinate of the component’s upper-left corner within its parent component. java.awt.Container +add(comp: Component): Component Adds a component to the container. +add(comp: Component, index: int): Component Adds a component to the container with the specified index. Removes the component from the container. +remove(comp: Component): void +getLayout(): LayoutManager +setLayout(l: LayoutManager): void +paintComponents(g: Graphics): void Returns the layout manager for this container. Sets the layout manager for this container. Paints each of the components in this container. The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity. javax.swing.JComponent The tool tip text for this component. Tool tip text is displayed when the mouse points on the component without clicking. EE3206/EE5805 Java Programming & Applications The border for this component. -border: javax.swing.border.Border -toolTipText: String 22 Borders Borders You You can set a border on any object of the JComponent class. Swing has several types of borders. To create a titled border, use new new TitledBorder(String title); To To create a line border, use new new LineBorder(Color color, int width); where width specifies the thickness of the line. For For example, the following code displays a titled border on a panel: JPanel JPanel panel = new JPanel(); panel.setBorder(new panel.setBorder(new TitleBorder(“My Panel”)); EE3206/EE5805 Java Programming & Applications 23 Test Test Swing Common Features Example Component Properties font font background background foreground foreground preferredSize preferredSize minimumSize minimumSize maximumSize maximumSize JComponent Properties toolTipText toolTipText border border TestSwingCommonFeatures Run EE3206/EE5805 Java Programming & Applications 24 Image Image Icons Java Java uses the javax.swing.ImageIcon class to represent an icon. An icon is a fixed-size picture; typically it is small and used to decorate fixedcomponents. Images are normally stored in image files. You You can use new ImageIcon(filename) to construct an image icon. For example, the following statement creates an icon from an image file us.gif in the image directory under the current class path: ImageIcon icon = new ImageIcon("image/us.gif"); TestImageIcon Run EE3206/EE5805 Java Programming & Applications 25 ...
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