Lesson 5 GUI Programming AUBG ICoSCIS Team Assoc. Prof. Stoyan Bonev March, , 2013 SWU, Blagoevgrad

3 Lesson Contents: §Building Win apps technologies using Java & class libraries l Swing l AWT (Abstract Windows Toolkit)

4 Java GUI programming §Java GUI programming has its own specific: l Terminology l Concept l Philosophy l Ideology l Technologies: Hand-made programming (project:Java, Java application) Visual, component programming (project:Java, Java Desktop application)

5 Terminology §Java Microsoft l Frame Form l Panel l Palette Toolbox

6 Concept, Philosophy, Ideology §Based on class libraries, grouped in packages §When Java was introduced, GUI classes bundled in AWT library §The 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.

7 The Java GUI API – 3 groups of classes §Component classes – used for creating UI l JButton, JLabel, JTextField, … §Container classes – used to contain other components l JFrame, JPanel, JApplet §Helper classes – used to support GUI components. l Graphics, Color, Font, FontMetrics, Dimension

GUI Class Hierarchy (Swing)

Swing GUI Components

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

Frames – To create empty frame l Practice: Recommended IDE: NetBeans l Create your own project: sbJavaWinEmptyForm Hand-made programming (project:Java, Java application) l Type import javax.swing.*; l Type stmt within main() method to create a frame JFrame mySBForm = new JFrame("Empty Form"); l Run the project No frame appears on the screen

Frames – To create empty frame l Frame not visible if method setVisible() not invoked l Add one more stmt mySBForm.setVisible(true); l Do you see the form? Look at the top left corner of the screen

Frames – To create empty frame l Frame may move to the center of the screen using method setLocationRelativeTo() l Add one more stmt mySBForm.setLocationRelativeTo(null); l Do you see the form? Look at the screen center

Frames – To create empty frame l Frame sized to display just the title bar if method setSize() not used l Add one more stmt mySBForm.setSize(900, 300); // dimensions in pixels l Do you see the effect of the change? l Hint: setSize() to invoke before invoking setLocationRelativeTo()

Frames – To create empty frame l How to tell the program to terminate when the frame gets closed? l Add one more stmt mySBForm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); l If this stmt is not used, the program does not terminate when the frame is closed

Adding components to a frame l Modify the frame constructor argument JFrame mySBForm = new JFrame("Empty Form"); To JFrame mySBForm = new JFrame(“My frame with Components");

Adding components to a frame l To add a component, we must : Create a component Add it to the frame (to the content pane of the frame) l This may happen in l Two steps JLabel myLabel1 = new Jlabel(“This is not Empty Frame”); mySBForm.add(myLabel1); l Or in one step creating anonymous component mySBForm.add(new JLabel(“This is not Empty Frame”));

Removing components from a frame l To remove a component, we must use method remove(): mySBForm.remove(myLabel1); l Can we remove anonymous component?

Adding two or more components to a frame l 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); l Do you see more than one component on the screen? l No. l What’s the problem?

Adding two or more components to a frame l 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. l It’s time to introduce several different layout managers to place components in the desired locations

Frames – To create empty frame l Practice: Recommended IDE: NetBeans Create your own project: sbJavaWinEmptyForm Visual, component programming (project:Java, Java Desktop application) l Use the toolbox facility to configure your project l Run the project

Layout Managers l For more details open file l LayoutManagersAndMore.ppt

More on GUI programming

10/7/2015Assoc. 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!

10/7/2015Assoc. 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!

28 GUI Basics or Windows Based Applications

29 Motivations To 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

30 Creating GUI Objects // Create a button with text OK JButton jbtOK = new JButton("OK"); Button LabelText field Check Box Radio Button Combo Box

31 Creating GUI Objects // Create a label with text "Enter your name: " JLabel jlblName = new JLabel("Enter your name: "); Button LabelText field Check Box Radio Button Combo Box

32 Creating GUI Objects // Create a text field with text "Type Name Here" JTextField jtfName = new JTextField("Type Name Here"); Button LabelText field Check Box Radio Button Combo Box

33 Creating GUI Objects // Create a check box with text bold JCheckBox jchkBold = new JCheckBox("Bold"); Button LabelText field Check Box Radio Button Combo Box

34 Creating GUI Objects // Create a radio button with text red JRadioButton jrbRed = new JRadioButton("Red"); Button LabelText field Check Box Radio Button Combo Box

35 Creating GUI Objects // Create a combo box with choices red, green, and blue JComboBox jcboColor = new JComboBox(new String[]{"Red", "Green", "Blue"}); Button LabelText field Check Box Radio Button Combo Box

36 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"}); Button LabelText field Check Box Radio Button Combo Box

37 Swing vs. AWT Swing class library OR AWT class library (Abstract Windows Toolkit)

38 Swing vs. AWT So 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.

39 GUI Class Hierarchy (Swing)

40 The Java GUI API §The Java GUI API contains classes that may classify in three groups: §Component classes l Used to create interface §Container classes l Used to contain components §Helper classes l Used to support components

41 AWT (Optional)

42 Frames §To 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.

43 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); }

44 Adding Components into a Frame // Add a button into the frame frame.getContentPane().add( new JButton("OK")); Title bar Content pane

45 Content Pane Delegation in JDK 1.5 // Add a button into the frame frame.getContentPane().add( new JButton("OK")); Title bar Content pane // Add a button into the frame frame.add( new JButton("OK") );

46 JFrame Class Demo: Open file ProgFrameAndControls.java

47 Demo – different source text structure – same functionality § Open file ProgFrameAndControls.java §Open file ProgFrameAndControlsStyleStandard.java §Open file ProgFrameAndControlsStyleRecommended.java §Open file ProgFrameAndControlsStyleSeparateClasses.java

48 Demo § Open file ProgFrameAndControls.java §You cannot visualize more than one component. §Each new component replaces the previous one §The 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() in context.setLayout( );

49 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.

50 Kinds of Layout Managers §FlowLayout §GridLayout §BorderLayout §Several other layout managers will be introduced in Chapter 33, “Containers, Layout Managers, and Borders”

51 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 control §Demo: file ProgFrameAndLayout.java

52 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

53 Exercises/Tasks §Try to run ProgFrameAndLayout.java program

54 FlowLayout Example §Run 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));

55 FlowLayout Example §Run 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));

56 FlowLayout Example Write a program that adds three labels and text fields into the content pane of a frame with a FlowLayout manager.

57 The FlowLayout Class

58 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

59 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));

60 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.

61 The GridLayout Class

62 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.

63 BorderLayout Example F ile ProgFrameAndLayout.java

64 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 text frame.add(jbtOK1, BorderLayout.EAST); frame.add(jbtOK2, BorderLayout.CENTER); frame.add(jbtOK3, BorderLayout.WEST); frame.add(jbtOK4, BorderLayout.NORTH); frame.add(jbtOK5, BorderLayout.SOUTH);

65 The BorderLayout Class

66 The Color Class 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. 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);

67 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.

68 Setting Colors You 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);

69 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 Names Standard font names that are supported in all platforms are: SansSerif, Serif, Monospaced, Dialog, or DialogInput. Font Style Font.PLAIN (0), Font.BOLD (1), Font.ITALIC (2), and Font.BOLD + Font.ITALIC (3)

70 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]);

71 Using Panels as Sub-Containers §Panels 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.

72 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"));

73 Demo § Open file ProgTestPanels.java § Open file ProgTestPanels2.java

74 Testing Panels Example This example uses panels to organize components. The program creates a user interface for a Microwave oven.

75 Common Features of Swing Components

76 Borders 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 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”));

77 Test Swing Common Features Component Properties §font §background §foreground §preferredSize §minimumSize §maximumSize JComponent Properties F toolTipText F border

78 Image Icons 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 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"); TestImageIconRun

79 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 l three labels l Three text fields l Two buttons §Scheme of the pane: label1 textfield1 label2 textfield2 label3 textfield3 button1 button2

81 Questions? And/Or Thank You For Your Attention!