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Chapter 11 Creating User Interfaces. What is JavaBean? JComponent JButton ImageIcon JLabel JTextField JTextArea JComboBox JList. JCheckBox JRadioButton Menus Creating Multiple Windows JScrollBar JScrollPane. JComponent Properties. toolTipText font background foreground

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Chapter 11 Creating User Interfaces

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Chapter 11 creating user interfaces l.jpg

Chapter 11Creating User Interfaces

  • What is JavaBean?

  • JComponent

  • JButton

  • ImageIcon

  • JLabel

  • JTextField

  • JTextArea

  • JComboBox

  • JList

  • JCheckBox

  • JRadioButton

  • Menus

  • Creating Multiple Windows

  • JScrollBar

  • JScrollPane


Jcomponent properties l.jpg

JComponent Properties

  • toolTipText

  • font

  • background

  • foreground

  • doubleBuffered

  • border

  • preferredSize

  • minimumSize

  • maximumSize


Jbutton l.jpg

JButton

A button is a component that triggers an action event when clicked. The following are JButton non-default constructors:

JButton(String text)

JButton(String text, Icon icon)

JButton(Icon icon)


Jbutton properties l.jpg

JButton Properties

  • text

  • icon

  • mnemonic

  • horizontalAlignment

  • verticalAlignment

  • horizontalTextPosition

  • verticalTextPosition


Responding to jbutton events l.jpg

Responding to JButton Events

public void actionPerformed(ActionEvent e) {

// Get the button label

String actionCommand = e.getActionCommand();

// Make sure the event source is a button

if (e.getSource() instanceof JButton)

// Make sure it is the right button

if ("My Button".equals(actionCommand)

System.out.println ("Button pressed!");

}


Jbutton6 l.jpg

JButton

ButtonDemo

Run


Jlabel l.jpg

JLabel

A label is a display area for a short text, an image, or both. The non-default constructors for labels are as follows:

JLabel(String text, int horizontalAlignment)

JLabel(String text)

JLabel(Icon icon)

JLabel(Icon icon, int horizontalAlignment)


Jlabel properties l.jpg

JLabel Properties

  • text

  • icon

  • horizontalAlignment

  • verticalAlignment


Example 11 2 using labels l.jpg

Example 11.2: Using Labels

This example gives a program that uses a label as an area for displaying images. There are fifty-two images in image files named L1.gif, L2.gif, ..., L52.gif stored in the image directory under c:\book. You can use two buttons, Prior and Next, to browse the images.

LabelDemo

Run


Jtextfield l.jpg

JTextField

A text field is an input area where the usercan type in characters. Text fields are usefulin that they enable the user to enter in variable data (such as a name or a description).


Jtextfield constructors l.jpg

JTextField Constructors

  • JTextField(int columns)

    Creates an empty text field with the specified number of columns.

  • JTextField(String text)

    Creates a text field initialized with the specified text.

  • JTextField(String text, int columns)

    Creates a text field initialized with thespecified text and the column size.


Jtextfield properties l.jpg

JTextField Properties

  • text

  • horizontalAlignment

  • editable

  • columns


Jtextfield methods l.jpg

JTextField Methods

  • getText()

    Returns the string from the text field.

  • setText(String text)

    Puts the given string in the text field.

  • setEditable(boolean editable)

    Enables or disables the text field to be edited. By default, editable is true.

  • setColumns(int)

    Sets the number of columns in this text field.The length of the text field is changeable.


Example 11 3 using text fields l.jpg

Example 11.3: Using Text Fields

This example gives a program that enters two numbers in two text fields and displays their sum in the third text field when you press the Add button.

TextFieldDemo

Run


Jtextarea l.jpg

JTextArea

If you want to let the user enter multiple lines of text, you cannot use text fields unless you create several of them. The solution is to use JTextArea, which enables the user to enter multiple lines of text.


Jtextarea constructors l.jpg

JTextArea Constructors

  • JTextArea(int rows, int columns)

    Creates a text area with the specified number of rows and columns.

  • JTextArea(String s, int rows, int columns)

    Creates a text area with the initial text andthe number of rows and columns specified.


Jtextarea properties l.jpg

JTextArea Properties

  • text

  • editable

  • columns

  • lineWrap

  • wrapStyleWord

  • rows

  • lineCount

  • tabSize


Example 11 4 using text areas l.jpg

Example 11.4 Using Text Areas

  • This example gives a program that displays an image in a label, a title in a label, and a text in a text area.


Example 11 4 cont l.jpg

Example 11.4, cont.

TextAreaDemo

Run


Jcombobox l.jpg

JComboBox

A combo box is a simple list of items from which the user can choose. It performs basically the same function as a list, but can get only one value. To create a choice, use its default constructor:

JComboBox()


Jcombobox methods l.jpg

JComboBox Methods

To add an item to a JComboBox jcbo, use

jcbo.addItem(Object item)

To get an item from JComboBox jcbo, use

jcbo.getItem()


Using the itemstatechanged handler l.jpg

Using theitemStateChanged Handler

public void itemStateChanged(ItemEvent e) {

// Make sure the source is a combo box

if (e.getSource() instanceof JComboBox)

String s = (String)e.getItem();

}

When a choice is checked or unchecked, itemStateChanged() for ItemEvent is invoked as well as the actionPerformed() handler for ActionEvent.


Example 11 5 using combo boxes l.jpg

Example 11.5: Using Combo Boxes

This example lets users view an image and a description of a country's flag by selecting the country from a combo box. Figure 11.8 shows a sample run of the program.

ComboBoxDemo

Run


Jlist l.jpg

JList

A list is a component that performs basically the same function as a combo box, but it enables the user to choose a single value or multiple values.


Jlist constructors l.jpg

JList Constructors

  • JList()

    Creates an empty list.

  • JList(Object[] stringItems)

    Creates a new list initialized with items.


Jlist properties l.jpg

JList Properties

  • selectedIndexd

  • selectedIndices

  • selectedValue

  • selectedValues

  • selectionMode

  • visibleRowCount


Example 11 6 using lists l.jpg

Example 11.6: Using Lists

This example gives a program that lets users select countries in a list and display the flags of the selected countries in the labels.

ListDemo

Run


Jcheckbox l.jpg

JCheckBox

A check box is a component that enables the user to toggle a choice on or off, like a light switch.


Jcheckbox constructors l.jpg

JCheckBox Constructors

  • JCheckBox()

  • JCheckBox(String text)

  • JCheckBox(String text, boolean selected)

  • JCheckBox(Icon icon)

  • JCheckBox(String text, Icon icon)

  • JCheckBox(String text, Icon icon, boolean selected)


Jcheckbox properties l.jpg

JCheckBox Properties

JCheckBox has all the properties in JButton. Additionally, JButton has the following property:

selected


Example 11 7 using check boxes l.jpg

Example 11.7: Using Check Boxes

This example gives a program that can dynamically change the font of a message to be displayed on a panel. The message can be displayed in bold and italic at the same time, or can be displayed in the center of the panel.

CheckBoxDemo

Run


Jradiobutton l.jpg

JRadioButton

Radio buttons are variations of check boxes. They are often used in the group, where only one button is checked at a time.


Jradiobutton33 l.jpg

JRadioButton

Radio buttons are variations of check boxes. They are often used in the group, where only one button is checked at a time.


Jradiobutton constructors l.jpg

JRadioButton Constructors

  • JRadioButton()

  • JRadioButton(String text)

  • JRadioButton(String text, boolean selected)

  • JRadioButton(Icon icon)

  • JRadioButton(String text, Icon icon)

  • JRadioButton(String text, Icon icon, boolean selected)


Jradiobutton properties l.jpg

JRadioButton Properties

JRadioButton has all the properties in JButton. Additionally, JButton has the following property:

selected


Grouping radio buttons l.jpg

Grouping Radio Buttons

ButtonGroup btg = new ButtonGroup();

btg.add(jrb1);

btg.add(jrb2);


Example 11 8 using radio buttons l.jpg

Example 11.8: Using Radio Buttons

This example shows a program that simulates traffic lights. The program lets the user select one of three lights: red, yellow, or green. When a radio button is selected, the light is turned on, and only one light can be on at a time. No light is on when the program starts.

RadioButtonDemo

Run


Borders l.jpg

Borders

You can set a border on any object of the JComponent class, but often it is useful to set a titled border on a JPanel that groups a set of related user interface components.


Static method for creating borders l.jpg

Static Method for Creating Borders

  • createTitledBorder(String title)

  • createLoweredBevelBorder()

  • createRaisedBevelBorder()

  • createLineBorder(Color color)

  • createLineBorder(Color color, int thickness)

  • createEtchedBorder()

  • createEtchedBorder(Color highlight, Color shadow, boolean selected)

  • createEmptyBorder()

  • createMatteBorder(int top, int left, int bottom, int right, Icon tileIcon)

  • createCompoundBorder(Border outsideBorder, Border insideBorder)


Example 11 9 using borders l.jpg

Example 11.9: Using Borders

This example gives a program that creates and displays various types of borders. You can select a border with a title or without a title. For a border without a title, you can choose a border style from Lowered Bevel, Raised Bevel, Etched, Line, Matte, or Empty. For a border with a title, you can specify the title position and justification. You can also embed another border into a titled border.


Example 11 9 cont l.jpg

Example 11.9, cont.

BorderDemo

Run


Joptionpane dialogs l.jpg

JOptionPane Dialogs

  • A dialog is normally used as a temporary window to receive additional information from the user, or to provide notification that some event has occurred.


Message dialogs l.jpg

Message Dialogs

A message dialog box simply displays a message to alert the user and waits for the user to click the OK button to close the dialog.


Message types l.jpg

Message Types

The messageType is one of the following constants:

JOptionPane.ERROR_MESSAGE

JOptionPane.INFORMATION_MESSAGE

JOptionPane.PLAIN_MESSAGE

JOptionPane.WARNING_MESSAGE

JOptionPane.QUESTION_MESSAGE


Message types cont l.jpg

Message Types, cont.


Confirmation dialogs l.jpg

Confirmation Dialogs

A message dialog box displays a message and waits for the user to click the OK button to dismiss the dialog. The message dialog does not return any value. A confirmation dialog asks a question and requires the user to respond with an appropriate button. The confirmation dialog returns a value that corresponds to a selected button.


Input dialogs l.jpg

Input Dialogs

An input dialog box is used to receive input from the user. The input can be entered from a text field or selected from a combo box or a list. Selectable values can be specified in an array, and a particular value can be designated as the initial selected value.


Option dialogs l.jpg

Option Dialogs

An option dialog allows you to create custom buttons.


Example 11 10 creating standard dialogs l.jpg

Example 11.10: Creating Standard Dialogs

  • Objective: This example demonstrates using standard dialogs. The program prompts the user to select the annual interest rate from a list in an input dialog, the number of years from a combo box in an input dialog, and the loan amount from an input dialog, and displays the loan payment schedule in a text area inside a JScrollPane in a messasge dialog.


Example 11 10 creating standard dialogs cont l.jpg

Example 11.10: Creating Standard Dialogs, cont.

JOptionPaneDemo

Run


Menus l.jpg

Menus

  • Java provides several classes—JMenuBar, JMenu, JMenuItem, JCheckBoxMenuItem, and JRadioButtonMenuItem —to implement menus in a frame.

  • A JFrame or JApplet can hold a menu bar to which the pull-down menus are attached. Menus consist of menu items that the user can select (or toggle on or off). Menu bars can be viewed as a structure to support menus.


Menu demo l.jpg

Menu Demo


The jmenubar class l.jpg

The JMenuBar Class

A menu bar holds menus; the menu bar can only be added to a frame. Following is the code to create and add a JMenuBar to a frame:

JFrame f = new JFrame();

f.setSize(300, 200);

f.setVisible(true);

JMenuBar mb = new JMenuBar(); f.setJMenuBar(mb);


The menu class l.jpg

The Menu Class

You attach menus onto a JMenuBar. The following code creates two menus, File and Help, and adds them to the JMenuBar mb:

JMenu fileMenu = new JMenu("File", false);

JMenu helpMenu = new JMenu("Help", true);

mb.add(fileMenu);

mb.add(helpMenu);


The jmenuitem class l.jpg

The JMenuItem Class

You add menu items on a menu. The following code adds menu items and item separators inmenu fileMenu:

fileMenu.add(new JMenuItem("new"));

fileMenu.add(new JMenuItem("open"));

fileMenu.add(new JMenuItem("-"));

fileMenu.add(new JMenuItem("print"));

fileMenu.add(new JMenuItem("exit"));

fileMenu.add(new JMenuItem("-"));


Submenus l.jpg

Submenus

You can add submenus into menu items. The following code adds the submenus “Unix,” “NT,” and “Win95” into the menu item “Software.”

JMenu softwareHelpSubMenu = new JMenu("Software");

JMenu hardwareHelpSubMenu = new JMenu("Hardware");

helpMenu.add(softwareHelpSubMenu);

helpMenu.add(hardwareHelpSubMenu);

softwareHelpSubMenu.add(new JMenuItem("Unix"));

softwareHelpSubMenu.add(new JMenuItem("NT"));

softwareHelpSubMenu.add(new JMenuItem("Win95"));


Submenu demo l.jpg

Submenu Demo


Example 11 11 using menus l.jpg

Example 11.11: Using Menus

  • Objective: Create a user interface that performs arithmetic. The interface contains labels and text fields for Number 1, Number 2, and Result. The Result box displays the result of the arithmetic operation between Number 1 and Number 2.


Example 11 11 cont l.jpg

Example 11.11, cont.

MenuDemo

Run


Creating multiple windows l.jpg

Creating Multiple Windows

The following slides show step-by-step how to create an additional window from an application or applet.


Slide61 l.jpg

Creating Additional Windows, Step 1

Step 1: Create a subclass of JFrame (called a SubFrame) that tells the new window whatto do. For example, all the GUI application programs extend JFrame and are subclassesof JFrame.


Creating additional windows step 2 l.jpg

Creating Additional Windows, Step 2

Step 2: Create an instance of SubFrame in the application or applet.

Example:

SubFrame subFrame = new

SubFrame("SubFrame Title");


Creating additional windows step 3 l.jpg

Creating Additional Windows, Step 3

Step 3: Create a JButton for activating the subFrame.

add(new JButton("Activate SubFrame"));


Creating additional windows step 4 l.jpg

Creating Additional Windows, Step 4

Step 4: Override the actionPerformed()method as follows:

public actionPerformed(ActionEvent e) {

String actionCommand = e.getActionCommand();

if (e.target instanceof Button) {

if ("Activate SubFrame".equals(actionCommand)) {

subFrame.setVisible(true);

}

}

}


Example 11 12 creating multiple windows l.jpg

Example 11.12 Creating Multiple Windows

  • This example creates a main window with a text area in the scroll pane, and a button named "Show Histogram." When the user clicks the button, a new window appears that displays a histogram to show the occurrence of the letters in the text area.


Example 11 12 cont l.jpg

Example 11.12, cont.

MultipleWindowsDemo

Run

Histogram


Jscrollbar l.jpg

JScrollBar

  • A scroll bar is a control that enables the user to select from a range of values. The scrollbar appears in two styles: horizontal and vertical.


Scroll bar properties l.jpg

Scroll Bar Properties


Example 11 13 using scrollbars l.jpg

Example 11.13: Using Scrollbars

This example uses horizontal and vertical scrollbars to control a message displayed on a panel. The horizontal scrollbar is used to move the message to the left or the right, and the vertical scrollbar to move it up and down.

ScrollBarDemo

Run


Jscrollpane l.jpg

JScrollPane

  • A scroll pane is a component that supports automatically scrolling without coding.


Example 11 14 using scroll panes l.jpg

Example 11.14: Using Scroll Panes

This example uses a scroll pane to browse a large map. The program lets you choose a map from a combo box and display it in the scroll pane,

ScrollPaneDemo

Run


Scroll pane structures l.jpg

Scroll Pane Structures


Jtabbedpane l.jpg

JTabbedPane

  • A tabbed pane provides a set of mutually exclusive tabs for accessing multiple components.


Example 11 15 using tabbed panes l.jpg

Example 11.15: Using Tabbed Panes

This example uses a tabbed pane with four tabs to display four types of figures: Square, Rectangle, Circle, and Oval. You click the corresponding tab to select a figure to be displayed. You can also use the radio buttons to specify the tab placement.

TabbedPaneDemo

Run


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