Download Chapter 11 Creating User Interfaces

Chapter 13
Creating User Interfaces
Chapter 8 Inheritance and Polymorphism
Chapter 9 Abstract Classes and Interfaces
Chapter 11 Getting Started with GUI Programming
Chapter 12 Event-Driven Programming
Chapter 13 Creating User Interfaces
Chapter 14 Applets, Images, Audio
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1
Objectives





To create graphical user interfaces with various user-interface
components: JButton, JCheckBox, JRadioButton, JLabel,
JTextField, JTextArea, JComboBox, JList, JScrollBar, and JSlider
(§13.2 – 13.12).
To create listeners for various types of events (§13.2 – 13.12).
To use borders to visually group user-interface components
(§13.2).
To create image icons using the ImageIcon class (§13.3).
To display multiple windows in an application (§13.13).
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2
Components Covered in the Chapter
Introduces
the frequently used GUI components
Uses borders and icons
JButton
Component
Container
JComponent
AbstractButton
JCheckBox
JToggleButton
JRadioButton
JLabel
JTextField
JTextComponent
JTextArea
JComboBox
JList
JScrollBar
JSlider
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3
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 TitleBorder(“My Panel”));
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4
Test Swing Common Features
Component Properties
JComponent Properties
font
 background
 foreground
 preferredSize
 minimumSize
 maximumSize
 toolTipText

 border
TestSwingCommonFeatures
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Buttons
A button is a component that triggers an action event
when clicked. Swing provides regular buttons,
toggle buttons, check box buttons, and radio buttons.
The common features of these buttons are
represented in javax.swing.AbstractButton.
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JButton
JButton inherits AbstractButton and provides several
constructors to create buttons.
javax.swing.AbstractButton
javax.swing.JButton
+JButton()
Creates a default button with no text and icon.
+JButton(icon: javax.swing.Icon)
Creates a button with an icon.
+JButton(text: String)
Creates a button with text.
+JButton(text: String, icon: Icon)
Creates a button with text and an icon.
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Icons
An icon is a fixed-size picture; typically it is
small and used to decorate components.
javax.swing.Icon is an interface. To create
an image, use its concrete class
javax.swing.ImageIcon. For example, the
following statement creates an icon from an
image file:
Icon icon = new ImageIcon("photo.gif");
TestButtonIcons
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Default Icons, Pressed Icon, and
Rollover Icon
A regular button has a default icon, pressed icon,
and rollover icon. Normally, you use the default
icon. All other icons are for special effects. A
pressed icon is displayed when a button is pressed
and a rollover icon is displayed when the mouse
is over the button but pressed.
(A) Default icon
(B) Pressed icon
(C) Rollover icon
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Horizontal Alignments
Horizontal alignment specifies how the icon and
text are placed horizontally on a button. You can set
the horizontal alignment using one of the five
constants: LEADING, LEFT, CENTER, RIGHT,
TRAILING. At present, LEADING and LEFT are
the same and TRAILING and RIGHT are the same.
Future implementation may distinguish them. The
default horizontal alignment is
SwingConstants.TRAILING.
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Vertical Alignments
Vertical alignment specifies how the icon and
text are placed vertically on a button. You can
set the vertical alignment using one of the
three constants: TOP, CENTER, BOTTOM.
The default vertical alignment is
SwingConstants.CENTER.
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Horizontal Text Positions
Horizontal text position specifies the
horizontal position of the text relative to the
icon. You can set the horizontal text position
using one of the five constants: LEADING,
LEFT, CENTER, RIGHT, TRAILING. The
default horizontal text position is
SwingConstants.RIGHT.
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Vertical Text Positions
Vertical text position specifies the vertical
position of the text relative to the icon. You
can set the vertical text position using one of
the three constants: TOP, CENTER. The
default vertical text position is
SwingConstants.CENTER.
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Example 13.1: Using Buttons
Write a program that displays a
message on a panel and uses
two buttons, <= and =>, to move
the message on the panel to the
left or right.
ButtonDemo
MessagePanel
JButton
JButton
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JCheckBox
JCheckBox inherits all the properties such as text, icon,
mnemonic, verticalAlignment, horizontalAlignment,
horizontalTextPosition, verticalTextPosition, and selected
from AbstractButton, and provides several constructors to
create check boxes.
javax.swing.AbstractButton
javax.swing.JToggleButton
javax.swing.JCheckBox
+JCheckBox()
Creates a default check box button with no text and icon.
+JCheckBox(text: String)
Creates a check box with text.
+JCheckBox(text: String, selected:
boolean)
Creates a check box with text and specifies whether the check box is
initially selected.
+JCheckBox(icon: Icon)
Creates a checkbox with an icon.
+JCheckBox(text: String, icon: Icon)
Creates a checkbox with text and an icon.
+JCheckBox(text: String, icon: Icon,
selected: boolean)
Creates a check box with text and an icon, and specifies whether the check
box is initially selected.
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Example 13.2: Using Check Boxes
Add three check boxes named
Centered, Bold, and Italic into
Example 13.1 to let the user
specify whether the message
is centered, bold, or italic.
ButtonDemo
CheckBoxDemo
CheckBoxDemo
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JRadioButton
Radio buttons are variations of check boxes. They are
often used in the group, where only one button is
checked at a time.
javax.swing.AbstractButton
javax.swing.JToggleButton
javax.swing.JRadioButton
+JRadioButton()
Creates a default radio button with no text and icon.
+JRadioButton(text: String)
Creates a radio button with text.
+JRadioButton(text: String, selected:
boolean)
Creates a radio button with text and specifies whether the radio button is
initially selected.
+JRadioButton(icon: Icon)
Creates a radio button with an icon.
+JRadioButton(text: String, icon: Icon)
Creates a radio button with text and an icon.
+JRadioButton(text: String, icon: Icon,
selected: boolean)
Creates a radio button with text and an icon, and specifies whether the radio
button is initially selected.
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Grouping Radio Buttons
ButtonGroup btg = new ButtonGroup();
btg.add(jrb1);
btg.add(jrb2);
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Example 13.3: Using Radio Buttons
Add three radio buttons
named Red, Green, and
Blue into the preceding
example to let the user
choose the color of the
message.
ButtonDemo
CheckBoxDemo
RadioButtonDemo
RadioButtonDemo
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JLabel
A label is a
display area
for a short
text, an image,
or both.
javax.swing.JComponent
javax.swing.JLabel
+JLabel()
Creates a default label with no text and icon.
+JLabel(icon: javax.swing.Icon)
Creates a label with an icon.
+JLabel(icon: Icon, hAlignment: int)
Creates a label with an icon and the specified horizontal alignment.
+JLabel(text: String)
Creates a label with text.
+JLabel(text: String, icon: Icon,
hAlignment: int)
Creates a label with text, an icon and the specified horizontal alignment.
+JLabel(text: String, hAlignment: int)
Creates a label with text and the specified horizontal alignment.
+getText(): String
Returns the label’s text.
+setText(text: String): void
Sets the label’s text.
+getIcon(): javax.swing.Icon
Returns the label’s image icon.
+setIcon(icon: Icon): void
Sets an image icon on the label.
+getHorizontalAlignment(): int
Returns the horizontal alignment of the text and icon on the label.
+setHorizontalAlignment(alignment: int): Sets the horizontal alignment – same as for buttons.
void
+getHorizontalTextPosition(): int
Returns the horizontal text position relative to the icon on the label.
+setHorizontalTextPosition(textPosition: Sets the horizontal text position – same as for buttons.
int): void
+getVerticalAlignment(): int
Returns the vertical alignment of the text and icon on the label.
+setVerticalAlignment(vAlignment: int): Sets the vertical alignment – same as for buttons.
void
+getVerticalTextPosition(): int
Returns the vertical text position relative to the icon on the label.
+setVerticalTextPosition(vTextPosition:
int) : void
Sets the vertical text position – same as for buttons
+getIconTextGap(): int
Returns the gap between the text and the icon on the label. (JDK 1.4)
+setIconTextGap(iconTextGap: int): void Sets a gap between the text and the icon on the label. (JDK 1.4)
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Using Labels
// Create an image icon from image file
ImageIcon icon = new ImageIcon("image/grapes.gif");
// Create a label with text, an icon,
// with centered horizontal alignment
JLabel jlbl = new JLabel("Grapes", icon,
SwingConstants.CENTER);
// Set label's text alignment and gap between text and icon
jlbl.setHorizontalTextPosition(SwingConstants.CENTER);
jlbl.setVerticalTextPosition(SwingConstants.BOTTOM);
jlbl.setIconTextGap(5);
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JTextField
A text field is an input area where the user
can type in characters. Text fields are useful
in that they enable the user to enter in variable data
(such as a name or a description).
javax.swing.text.JTextComponent
+getText(): String
Returns the text contained in this text component.
+setText(text: String): void
Sets a text in this text component.
+isEditable(): boolean
Indicates whether this text component is editable.
+setEditable(b: boolean): void
Sets the text component editable or prevents it from being edited.
(default: true)
javax.swing.JTextField
+JTextField()
Creates a default empty text field with number of columns set to 0.
+JTextField(column: int)
Creates an empty text field with specified number of columns.
+JTextField(text: String)
Creates a text field initialized with the specified text.
+JTextField(text: String, columns: int)
Creates a text field initialized with the specified text and columns.
+getColumns(): int
Returns the number of columns in this text field.
+setColumns(columns: int): void
Sets the number of columns in this text field.
+getHorizontalAlignment(): int
Returns the horizontal alignment of this text field.
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+setHorizontalAlignment(alignment:
int):
voidProgramming,
Sets the horizontal
alignment
for thisEducation,
text field.Inc.
(default:
LEFT)
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Example 13.4: Using Text Fields
Add a text field to the
preceding example to
let the user set a new
message.
ActionListener
ButtonDemo
CheckBoxDemo
RadioButtonDemo
TextFieldDemo
JFrame
TextFieldDemo
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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.
javax.swing.text.JTextComponent
javax.swing.JTextArea
+JTextArea()
Creates a default empty text area.
+JTextArea(rows: int, columns: int)
Creates an empty text area with the specified number of rows and columns.
+JTextArea(text: String)
Creates a new text area with the specified text displayed.
+JTextArea(text: String, rows: int, columns: int) Creates a new text area with the specified text and number of rows and columns.
+append(s: String): void
Appends the string to text in the text area.
+insert(s: String, pos: int): void
Inserts string s in the specified position in the text area.
+replaceRange(s: String, start: int, end: int): void Replaces partial text in the range from position start to end with string s.
+getColumns(): int
Returns the number of columns in this text area.
+setColumns(columns: int): void
Sets the number of columns in this text area.
+getRows(): int
Returns the number of rows in this text area.
+setRows(rows: int): void
Sets the number of rows in this text area.
+getLineCount(): int
Returns the actual number of lines contained in the text area.
+getTabSize(): int
Returns the number of characters used to expand tabs in this text area.
+setTabSize(size: int): void
Sets the number of characters to expand tabs to. (default: 8)
+getLineWrap(): boolean
Indicates whether the line in the text area is automatically wrapped.
+setLineWrap(wrap: boolean): void
Sets the line-wrapping policy of the text area. (default: false)
+getWrapStyleWord(): boolean
Indicates whether the line is wrapped on words or characters.
+setWrapStyleWord(word: boolean): void
Sets the style of wrapping used if the text area is wrapping lines. The default
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Example 13.5 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.
JPanel
JFrame
-char token
+getToken
DescriptionPanel
+setToken
+paintComponet
-jlblImage: JLabel
+mouseClicked
-jlblTitle: JLabel
-jtaTextDescription: JTextArea
-char token
1
1
+getToken
TextAreaDemo
+setToken
+paintComponet
+mouseClicked
+setImageIcon(icon: ImageIcon): void
+setTitle(title: String): void
+setTextDescription(text: String): void
+getMinimumSize(): Dimension
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Example 13.5, cont.
TextAreaDemo
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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.
javax.swing.JComponent
javax.swing.JComboBox
+JComboBox()
Creates a default empty combo box.
+JComboBox(items: Object[])
Creates a combo box that contains the elements in the specified array.
+addItem(item: Object): void
Adds an item to the combo box.
+getItemAt(index: int): Object
Returns the item at the specified index.
+getItemCount(): int
Returns the number of items in the combo box.
+getSelectedIndex(): int
Returns the index of the selected item.
+setSelectedIndex(index: int): void
Sets the selected index in the combo box.
+getSelectedItem(): Object
Returns the selected item.
+setSelectedItem(item: Object): void
Sets the selected item in the combo box.
+removeItem(anObject: Object): void Removes an item from the item list.
Removes the item at the specified index in the combo box.
+removeItemAt(anIndex: int): void
+removeAllItems(): void
Removes all items in the combo box.
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Using the
itemStateChanged Handler
When a choice is checked or unchecked,
itemStateChanged() for ItemEvent is
invoked as well as the actionPerformed()
handler for ActionEvent.
public void itemStateChanged(ItemEvent e) {
// Make sure the source is a combo box
if (e.getSource() instanceof JComboBox)
String s = (String)e.getItem();
}
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Example 13.6: 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.
ComboBoxDemo
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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.
javax.swing.JComponent
javax.swing.JList
+JList()
Creates a default empty list.
+JList(items: Object[])
Creates a list that contains the elements in the specified array.
+getSelectedIndex(): int
Returns the index of the first selected item.
+setSelectedIndex(index: int): void
Selects the cell at the specified index.
+getSelectedIndices(): int[]
Returns an array of all of the selected indices in increasing order.
+setSelectedIndices(indices: int[]): void Selects the cells at the specified indices.
+getSelectedValue(): Object
Returns the first selected item in the list.
+getSelectedValues(): Object[]
Returns an array of the values for the selected cells in increasing index order.
+getVisibleRowCount(): int
Returns the number of visible rows displayed without a scrollbar. (default: 8)
+setVisibleRowCount(count: int): void
Sets the preferred number of visible rows displayed without a scrollbar.
+getSelectionBackground(): Color
Returns the background color of the selected cells.
+setSelectionBackground(c: Color): void Sets the background color of the selected cells.
+getSelectionForeground(): Color
Returns the foreground color of the selected cells.
+setSelectionForeground(c: Color): void Sets the foreground color of the selected cells.
+getSelectionMode(): int
Returns the selection mode for the list.
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+setSelectionMode(selectionMode: int): Sets
thereserved.
selection
mode for the list.
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Example 13.7: 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
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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.
javax.swing.JComponent
javax.swing.JScrollBar
+JScrollBar()
Creates a default vertical scroll bar.
+JScrollBar(orientation: int)
Creates a scroll bar with the specified orientation.
+JScrollBar(orientation: int, value: int,
extent: int, min: int, max: int)
Creates a scrollbar with the specified orientation, value, extent, minimum, and
maximum.
+getBlockIncrement(): int
Returns the block increment.
+setBlockIncrement(increment: int): void Sets a new block increment. (default: 10)
+getMaximum(): int
Returns the maximum value represented by the scroll bar.
+setMaximum(maximum: int): void
Sets a new maximum. (default: 100)
+getMinimum(): int
Returns the minimum value represented by the scroll bar.
+setMinimum(minimum: int): void
Sets a new minimum. (default: 0)
+getOrientation(): int
Returns the orientation of the scroll bar.
+setOrientation(orientation: int): void
Sets a new orientation for the scroll bar.
+getUnitIncrement(): int
Returns the unit increment in the scroll bar.
+setUnitIncrement(increment: int): void
Sets a new unit increment in the scroll bar.
+getValue(): int
Returns the current value represented by the scroll bar.
+setValue(int value): void
Sets a new current value represented by the scroll bar.
+getVisibleAmount(): int
Returns the visible amount in the scroll bar.
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+setVisibleAmount(extent:
int): void
Sets Edition,
a new visible
amount
for the
scroll bar.
(default:
10)
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Scroll Bar Properties
Minimal value
Maximal value
Block decrement
Block increment
Bubble
Unit decrement
Unit increment
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Example 13.8: 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
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JSlider
JSlider is similar to JScrollBar, but JSlider has more
properties and can appear in many forms.
javax.swing.JComponent
javax.swing.JSlider
+JSlider()
Creates a default horizontal slider.
+JSlider(min: int, max: int)
Creates a horizontal slider using the specified min and max.
+JSlider(min: int, max: int, value: int)
Creates a horizontal slider using the specified min, max, and value.
+JSlider(orientation: int)
Creates a slider with the specified orientation.
+JSlider(orientation: int, min: int, max:
int, value: int)
Creates a slider with the specified orientation, min, max, and value.
+getInverted(): boolean
Returns true if the value-range shown for the slider is reversed.
+setInverted(b: boolean): void
Sets true to reverse the value-range, and false to put the value range in the
normal order. (default: false)
+getMajorTickSpacing(): int
Returns the number of units between major ticks.
+setMajorTickSpacing(n: int): void
Sets the number of units between major ticks. (default: 0)
+getMinorTickSpacing(): int
Returns the number of units between minor ticks.
+setMinorTickSpacing(n: int): void
Sets the number of units between minor ticks. (default: 0)
+getMaximum(): int
Returns the maximum value represented by the slider.
+setMaximum(maximum: int): void
Sets a new maximum. (default: 100)
+getMinimum(): int
Returns the minimum value represented by the slider.
+setMinimum(minimum: int): void
Sets a new minimum. (default: 0)
+getOrientation(): int
Returns the orientation of the slider.
+setOrientation(orientation: int): void
Sets a new orientation for the slider.
+getPaintLabels(): boolean
Returns true if the labels are painted at tick marks.
+setPaintLabels(b: boolean): void
Sets a Boolean value to determine whether labels are painted. (default: false)
+getPaintTicks(): boolean
Returns true if the ticks are painted on the slider.
+setPaintTicks(b: boolean): void
Sets a Boolean value to determine whether ticks are painted. (default: false)
+getPaintTrack(): boolean
Returns true if the track are painted on the slider.
+setPaintTrack(b: boolean): void
Sets a Boolean value to determine whether tracks are painted. (default: true)
+getValue(): int
Returns the current value represented by the slider.
+setValue(int value): void
a new value
represented
by the
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Example 13.9: Using Sliders
Rewrite the preceding
program using the sliders
to control a message
displayed on a panel
instead of using scroll
bars.
SliderDemo
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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);
}
}
}
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Example 13.10 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.
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Example 13.10, cont.
MultipleWindowsDemo
Histogram
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