lesson 5 gui programming aubg icoscis team assoc. prof. stoyan bonev march, 23 - 24, 2013 swu,...
TRANSCRIPT
Lesson 5GUI Programming
AUBG ICoSCIS TeamAssoc. Prof. Stoyan Bonev
March, 23 - 24, 2013 SWU, Blagoevgrad
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Lesson Contents:
Building Win apps technologies using Java & class libraries Swing AWT (Abstract Windows Toolkit)
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Java GUI programming
Java GUI programming has its own specific: Terminology Concept Philosophy Ideology Technologies:
• Hand-made programming (project:Java, Java application)• Visual, component programming (project:Java, Java
Desktop application)
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Terminology
Java Microsoft Frame Form Panel
Palette Toolbox
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Concept, Philosophy, Ideology
Based on class libraries, grouped in packagesWhen Java was introduced, GUI classes bundled in
AWT libraryThe AWT UI components were replaced by a more
robust and flexible library, known as Swing components.
To distinguish Swing components to their AWT counterparts, the Swing GUI components are named with a prefixed J.
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The Java GUI API – 3 groups of classes
Component classes – used for creating UI JButton, JLabel, JTextField, …
Container classes – used to contain other components JFrame, JPanel, JApplet
Helper classes – used to support GUI components. Graphics, Color, Font, FontMetrics, Dimension
GUI Class Hierarchy (Swing)
Dimension
Font
FontMetrics
Component
Graphics
Object Color
Container
Panel Applet
Frame
Dialog
Window
JComponent
JApplet
JFrame
JDialog
Swing Components in the javax.swing package
Lightweight
Heavyweight
Classes in the java.awt package
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LayoutManager
*
Swing GUI Components
JMenuItem
JCheckBoxMenuItem
AbstractButton
JComponent
JMenu
JRadioButtonMenuItem
JToggleButton JCheckBox
JRadioButton
JComboBox
JInternalFrame
JLayeredPane
JList
JMenuBar
JOptionPane
JPopupMenu
JProgressBar
JFileChooser
JScrollBar
JScrollPane JSeparator JSplitPane
JSlider
JTabbedPane
JTable JTableHeader
JTextField JTextComponent
JTextArea
JToolBar JToolTip
JTree
JRootPane
JPanel
JPasswordField
JColorChooser
JLabel
JEditorPane
JSpinner
JButton
Frames
To create a UI, you need a container, i.e. a frame.
Frame is a window that is not contained inside another window. Frame is the basis to contain other user interface components in Java GUI applications.
The JFrame class can be used to create windows.
For Swing GUI programs, use JFrame class to create windows.
Frames
import javax.swing.*;
public class 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);
}
}
Frames 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
+pack(): 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.
Automatically sets the frame size to hold the components in the frame.
Frames – To create empty frame
Practice: Recommended IDE: NetBeans Create your own project: sbJavaWinEmptyForm
• Hand-made programming (project:Java, Java application)
Type import javax.swing.*; Type stmt within main() method to create a frame
JFrame mySBForm = new JFrame("Empty Form");
Run the project• No frame appears on the screen
Frames – To create empty frame
Frame not visible if method setVisible() not invoked
Add one more stmt
mySBForm.setVisible(true);
Do you see the form? Look at the top left corner of the screen
Frames – To create empty frame
Frame may move to the center of the screen using method setLocationRelativeTo()
Add one more stmt
mySBForm.setLocationRelativeTo(null);
Do you see the form? Look at the screen center
Frames – To create empty frame
Frame sized to display just the title bar if method setSize() not used
Add one more stmt
mySBForm.setSize(900, 300); // dimensions in pixels
Do you see the effect of the change? Hint: setSize() to invoke before invoking setLocationRelativeTo()
Frames – To create empty frame
How to tell the program to terminate when the frame gets closed?
Add one more stmt
mySBForm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
If this stmt is not used, the program does not terminate when the frame is closed
Adding components to a frame
Modify the frame constructor argument
JFrame mySBForm = new JFrame("Empty Form");
ToJFrame mySBForm = new JFrame(“My frame with Components");
Adding components to a frame
To add a component, we must :• Create a component
• Add it to the frame (to the content pane of the frame) This may happen in Two steps
• JLabel myLabel1 = new Jlabel(“This is not Empty Frame”);
• mySBForm.add(myLabel1);
Or in one step creating anonymous component• mySBForm.add(new JLabel(“This is not Empty Frame”));
Removing components from a frame To remove a component, we must use method remove():
• mySBForm.remove(myLabel1);
Can we remove anonymous component?
Adding two or more components to a frame
To add more than one component, we must :• JLabel myLabel1 = new Jlabel(“This is not Empty Frame”);• mySBForm.add(myLabel1);• JLabel myLabel2 = new Jlabel(“This is Frame with components”);• mySBForm.add(myLabel2);• //JButton myBtn1 = new JButton(“My Button”);• //mySBForm.add(myBtn1);
Do you see more than one component on the screen? No. What’s the problem?
Adding two or more components to a frame
This is because components are put in the frame by the content pane’s layout manager and the default layout manager if not specified explicitly, allocates all the frame to the current component replacing/substituting the previous component if there is any.
It’s time to introduce several different layout managers to place components in the desired locations
Frames – To create empty frame
Practice: Recommended IDE: NetBeans Create your own project: sbJavaWinEmptyForm
• Visual, component programming (project:Java, Java Desktop application)
Use the toolbox facility to configure your project
Run the project
Layout Managers
For more details open file
LayoutManagersAndMore.ppt
More on GUI programming
04/19/23 Assoc. Prof. Stoyan Bonev 26
Load file dialogs
JFileChooser chooser = new JFileChooser();chooser.setDialogTitle("Load which file?");
int result = chooser.showOpenDialog(enclosingJFrame);if (result != JFileChooser.APPROVE_OPTION) { File file = chooser.getSelectedFile(); // use file}
You could also test for CANCEL_OPTION or ERROR_OPTION
You will get back a File object; to use it, you must know how to do file I/O!
04/19/23 Assoc. Prof. Stoyan Bonev 27
Save file dialogs
JFileChooser chooser = new JFileChooser();chooser.setDialogTitle(“Save file as?");
int result = chooser.showSaveDialog(enclosingJFrame);if (result != JFileChooser.APPROVE_OPTION) { File file = chooser.getSelectedFile(); // use file}
You could also test for CANCEL_OPTION or ERROR_OPTION
You will get back a File object; to use it, you must know how to do file I/O!
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GUI BasicsorWindows Based Applications
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MotivationsTo build Windows application you need a frame (with
title bar and content pane) structured to contain components/controls such as
buttons,
labels,
text fields,
check boxes,
radio buttons,
combo boxes, and others.
See next slide for illustration
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Creating GUI Objects
// Create a button with text OK JButton jbtOK = new JButton("OK");
Button
Label Text field
Check Box
Radio Button
Combo Box
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Creating GUI Objects
// Create a label with text "Enter your name: "JLabel jlblName = new JLabel("Enter your name: ");
Button
Label Text field
Check Box
Radio Button
Combo Box
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Creating GUI Objects
// Create a text field with text "Type Name Here"JTextField jtfName = new JTextField("Type Name Here");
Button
Label Text field
Check Box
Radio Button
Combo Box
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Creating GUI Objects
// Create a check box with text boldJCheckBox jchkBold = new JCheckBox("Bold");
Button
Label Text field
Check Box
Radio Button
Combo Box
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Creating GUI Objects
// Create a radio button with text redJRadioButton jrbRed = new JRadioButton("Red");
Button
Label Text field
Check Box
Radio Button
Combo Box
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Creating GUI Objects
// Create a combo box with choices red, green, and blueJComboBox jcboColor = new JComboBox(new String[]{"Red", "Green", "Blue"});
Button
Label Text field
Check Box
Radio Button
Combo Box
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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 boldJCheckBox jchkBold = new JCheckBox("Bold"); // Create a radio button with text redJRadioButton jrbRed = new JRadioButton("Red"); // Create a combo box with choices red, green, and blueJComboBox jcboColor = new JComboBox(new String[]{"Red", "Green", "Blue"});
Button
Label Text field
Check Box
Radio Button
Combo Box
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Swing vs. AWT
Swing class library
OR
AWT class library(Abstract Windows Toolkit)
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Swing vs. AWTSo why do the GUI component classes have a prefix J? Instead of JButton, why not name it simply Button? In fact, there is a class already named Button in the java.awt package.
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 components are automatically mapped to the platform-specific components through their respective agents, known as peers. AWT is fine for developing simple graphical user interfaces, but not for developing comprehensive GUI projects. Besides, AWT is prone to platform-specific bugs because its peer-based approach relies heavily on the underlying platform. With the release of Java 2, the AWT user-interface components were replaced by a more robust, versatile, and flexible library known as Swing components. Swing components are painted directly on canvases using Java code, except for components that are subclasses of java.awt.Window or java.awt.Panel, which must be drawn using native GUI on a specific platform. 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 heavyweight components.
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GUI Class Hierarchy (Swing)
Dimension
Font
FontMetrics
Component
Graphics
Object Color
Container
Panel Applet
Frame
Dialog
Window
JComponent
JApplet
JFrame
JDialog
Swing Components in the javax.swing package
Lightweight
Heavyweight
Classes in the java.awt package
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LayoutManager
*
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The Java GUI API
The Java GUI API contains classes that may classify in three groups:
Component classes Used to create interface
Container classes Used to contain components
Helper classes Used to support components
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AWT (Optional)AWTEvent
Font
FontMetrics
Component
Graphics
Object Color
Canvas
Button
TextComponent
Label
List
CheckBoxGroup
CheckBox
Choice
Container Panel Applet
Frame
Dialog FileDialog
Window
TextField
TextArea
MenuComponent MenuItem
MenuBar
Menu
Scrollbar
LayoutManager
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FramesTo create a user interface, you need to create a frame.
Frame is a window that is not contained inside another window. Frame is the basis to contain other user interface components in Java GUI applications.
The JFrame class can be used to create windows.
For Swing GUI programs, use JFrame class to create windows.
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Creating Frames(open file ProgPureFrame.java)
import javax.swing.*;public class MyFrame { public static void main(String[] args) { JFrame frame = new JFrame("Test Frame"); frame.setSize(400,300); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }
}
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Adding Components into a Frame// Add a button into the frameframe.getContentPane().add( new JButton("OK"));
Title bar
Content pane
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Content Pane Delegation in JDK 1.5// Add a button into the frameframe.getContentPane().add( new JButton("OK"));
Title bar
Content pane
// Add a button into the frameframe.add( new JButton("OK") );
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JFrame Class 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
+pack(): 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.
Automatically sets the frame size to hold the components in the frame.
Demo: Open file ProgFrameAndControls.java
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Demo – different source text structure – same functionality
Open file ProgFrameAndControls.javaOpen file ProgFrameAndControlsStyleStandard.javaOpen file
ProgFrameAndControlsStyleRecommended.javaOpen file
ProgFrameAndControlsStyleSeparateClasses.java
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Demo Open file ProgFrameAndControls.javaYou cannot visualize more than one component.Each new component replaces the previous oneThe component occupies all the frame space
How to proceed with more components?You need a layout manager to associate with the
container using method setLayout() incontext <container>.setLayout(<arg>);
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Layout Managers Java’s layout managers provide a level of abstraction to
automatically map your user interface on all window systems.
The UI components are placed in containers. Each container has a layout manager to arrange the UI components within the container.
Layout managers are set in containers using the setLayout(LayoutManager) method in a container.
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Kinds of Layout ManagersFlowLayout
GridLayout
BorderLayout
Several other layout managers will be introduced in Chapter 33, “Containers, Layout Managers, and Borders”
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FlowLayout Example
The simplest layout manager. Components arranged from left to right row by
row in the order in which they were added.Possible alignment controlDemo: file ProgFrameAndLayout.java
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NetBeans – functionality Introduction to GUI Building
Contents Exercise 1: Creating a Project Exercise 2: Building the Front End Exercise 3: Adding Functionality Exercise 4: Running the Program How Event Handling Works
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Exercises/Tasks
Try to run ProgFrameAndLayout.java program
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FlowLayout ExampleRun the ProgFrameAndLayout.java program as it is set
without layout manager:
// with and/or without layout manager
// frame.setLayout(new FlowLayout(FlowLayout.LEFT,10,20));
// frame.setLayout(new GridLayout( 3, 2, 10, 15));
// frame.setLayout(new BorderLayout( 10, 20));
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FlowLayout ExampleRun the ProgFrameAndLayout.java program as it is set
with FlowLayout layout manager:
// with and/or without layout manager
frame.setLayout(new FlowLayout(FlowLayout.LEFT,10,20));
// frame.setLayout(new GridLayout( 3, 2, 10, 15));
// frame.setLayout(new BorderLayout( 10, 20));
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FlowLayout Example
Write a program that adds three labels and text fields into the content pane of a frame with a FlowLayout manager.
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The FlowLayout Class
java.awt.FlowLayout
-alignment: int
-hgap: int
-vgap: int
+FlowLayout()
+FlowLayout(alignment: int)
+FlowLayout(alignment: int, hgap: int, vgap: int)
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.
The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity.
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GridLayout Example
Components arranged in a grid (matrix)
formation. from left to right row by row in the order in which they were added.
Demo: file ProgFrameAndLayout.java
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GridLayout Example
Run the ProgFrameAndLayout.java program as it is set with GridLayout layout manager:
// with and/or without layout manager// frame.setLayout(new FlowLayout(FlowLayout.LEFT,10,20)); frame.setLayout(new GridLayout( 3, 2, 10, 15));
// frame.setLayout(new BorderLayout( 10, 20));
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GridLayout Example
Rewrite the program in the preceding example using a GridLayout manager instead of a FlowLayout manager to display the labels and text fields.
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The GridLayout Class
java.awt.GridLayout
-rows: int
-columns: int
-hgap: int
-vgap: int
+GridLayout()
+GridLayout(rows: int, columns: int)
+GridLayout(rows: int, columns: int, hgap: int, vgap: int)
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.
Creates a GridLayout with a specified number of rows and columns.
Creates a GridLayout manager with a specified number of rows and columns, horizontal gap, and vertical gap.
The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity.
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The BorderLayout Manager
The BorderLayout manager divides the container into five areas: East, South, West, North, and Center. Components are added to a BorderLayout by using the add method.
add(Component, constraint), where constraint is BorderLayout.EAST, BorderLayout.SOUTH, BorderLayout.WEST, BorderLayout.NORTH, or BorderLayout.CENTER.
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BorderLayout ExampleFile ProgFrameAndLayout.java
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BorderLayout Example
Run the ProgFrameAndLayout.java program as it is set with BorderLayout layout manager:
// with and/or without layout manager// frame.setLayout(new FlowLayout(FlowLayout.LEFT,10,20));// frame.setLayout(new GridLayout( 3, 2, 10, 15)); frame.setLayout(new BorderLayout( 10, 20));
// uncomment this textframe.add(jbtOK1, BorderLayout.EAST);frame.add(jbtOK2, BorderLayout.CENTER);frame.add(jbtOK3, BorderLayout.WEST);frame.add(jbtOK4, BorderLayout.NORTH);frame.add(jbtOK5, BorderLayout.SOUTH);
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The BorderLayout Class
java.awt.BorderLayout
-hgap: int
-vgap: int
+BorderLayout()
+BorderLayout(hgap: int, vgap: int)
The horizontal gap of this layout manager (default: 0).
The vertical gap of this layout manager (default: 0).
Creates a default BorderLayout manager.
Creates a BorderLayout manager with a specified number of horizontal gap, and vertical gap.
The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity.
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The Color ClassYou 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.
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);
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Standard Colors
Thirteen standard colors (black, blue, cyan, darkGray, gray, green, lightGray, magenta, orange, pink, red, white, yellow) are defined as constants in java.awt.Color.
The standard color names are constants, but they are named as variables with lowercase for the first word and uppercase for the first letters of subsequent words. Thus the color names violate the Java naming convention. Since JDK 1.4, you can also use the new constants: BLACK, BLUE, CYAN, DARK_GRAY, GRAY, GREEN, LIGHT_GRAY, MAGENTA, ORANGE, PINK, RED, WHITE, and YELLOW.
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Setting ColorsYou can use the following methods to set the component’s background and foreground colors:
setBackground(Color c)
setForeground(Color c)
Example:
jbt.setBackground(Color.yellow);
jbt.setForeground(Color.red);
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The Font Class
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);
Font NamesStandard font names that are supported in all platforms are: SansSerif, Serif, Monospaced, Dialog, or DialogInput.
Font StyleFont.PLAIN (0), Font.BOLD (1), Font.ITALIC (2), and Font.BOLD + Font.ITALIC (3)
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Finding All Available Font Names
GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment();
String[] fontnames = e.getAvailableFontFamilyNames();
for (int i = 0; i < fontnames.length; i++)
System.out.println(fontnames[i]);
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Using Panels as Sub-ContainersPanels act as sub-containers for grouping user interface
components.
It is recommended that you place the user interface components in panels and place the panels in a frame. You can also place panels in a panel.
To add a component to JFrame, you actually add it to the content pane of JFrame.
To add a component to a panel, you add it directly to the panel using the .add method.
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Creating a JPanel
You can use new JPanel() to create a panel with a default FlowLayout manager or
new JPanel(LayoutManager) to create a panel with the specified layout manager. Use the add(Component) method to add a component to the panel. For example,
JPanel p = new JPanel();
p.add(new JButton("OK"));
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Demo
Open file ProgTestPanels.java
Open file ProgTestPanels2.java
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Testing Panels ExampleThis example uses panels to organize components. The program creates a user interface for a Microwave oven.
A button
A textfield
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buttons
frame
p2
p1
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Common Features of Swing Components
java.awt.Container
+add(comp: Component): Component
+add(comp: Component, index: int): Component
+remove(comp: Component): void
+getLayout(): LayoutManager
+setLayout(l: LayoutManager): void
+paintComponents(g: Graphics): void
Adds a component to the container.
Adds a component to the container with the specified index.
Removes the component from the container.
Returns the layout manager for this container.
Sets the layout manager for this container.
Paints each of the components in this container.
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 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.
javax.swing.JComponent
-toolTipText: String
-border: javax.swing.border.Border
The tool tip text for this component. Tool tip text is displayed when the mouse points on the component without clicking.
The border for this component.
The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity.
The get and set methods for these data fields are provided in the class, but omitted in the UML diagram for brevity.
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BordersYou can set a border on any object of the JComponent class. Swing has several types of borders. To create a titled border, use
new TitledBorder(String title).
To create a line border, use new LineBorder(Color color, int width),
where width specifies the thickness of the line. For example, the following code displays a titled border on a panel:
JPanel panel = new JPanel();panel.setBorder(new TitledBorder(“My Panel”));
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Test Swing Common FeaturesComponent Properties
font backgroundforegroundpreferredSizeminimumSizemaximumSize
JComponent Properties
toolTipTextborder
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Image IconsJava 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 components. Images are normally stored in image files. 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");
TestImageIconTestImageIcon RunRun
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Splash Screen
A splash screen is an image that is displayed while the application is starting up. If your program takes a long time to load, you may display a splash screen to alert the user. For example, the following command:
java –splash:image/us.gf TestImageIcon
displays an image while the program TestImageIcon is being loaded.
Task
Write JAVA program to support a frame with three labels Three text fields Two buttons
Scheme of the pane:label1 textfield1label2 textfield2label3 textfield3button1 button2
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Questions? And/Or
Thank You For
Your Attention!