This document provides an overview of Swing components for creating graphical user interfaces in Java. It discusses top-level containers like JFrame and JDialog, general purpose containers like JPanel and JScrollPane, basic controls for user input like JTextField and JButton, components for displaying information like JLabel and JTable, and various layout managers including FlowLayout, BorderLayout, GridLayout, BoxLayout, and GridBagLayout. It also covers using borders with components and implementing listeners for text fields. The document is intended to teach what is needed to create full-featured GUIs with Swing.

1. Topic 10: Swing User Interface Components
Chapter 9
Advanced Programming Techniques

2. Objective and Outline
• Objective:
– What else do you need to know in order to create a
full-featured GUI?
• Outline:
– Overview of Swing components
– Layout management
– Using Swing components
• Text input, Buttons, ComboBox, Menus, Dialogs

3. Overview of Swing Components
http://java.sun.com/docs/books/tutorial/uiswing/components/components.html
Top-Level Containers
 Windows: JFrame class
 Dialog boxes: JOptionPane,JDialog *,
JFileChooser classes
 Applets: JApplet * class
v2: covered in volume 2, *: will discuss

4. Overview of Swing Components
General-Purpose containers for laying out components.
 JPanel class
 JScrollPane * class provides a
scrollable view of components.
 JSplitPane v2 displays two groups of
components, either side by side or
one on top of the other.

5. Overview of Swing Components
Basic control: Components for getting user input
 Textfields: JTextField *,
JPasswordField *, JTextArea *
 Buttons: JButton *, JCheckBox *,
JRadioButton *, …


6. Overview of Swing Components
Basic control: Components for getting user input
 JMenu *, JMenuItem *
 JSlider v2, JScrollbar
 JComboBox *
 JSpinner

7. Overview of Swing Components
non-editable components for information display
 Jlabel * class can display
non-selectable text and images.
 JProgressBar v2 class displays
progress of a job.
 Tool Tips v2: created using JComponent

8. Overview of Swing Components
Editable components for information display
 JTable v2 class can display and edit
tables of data,
 Texts *:
 JTree v2 class can display
hierarchical data
 File Chooser
 JColorChooser class to provide users
with a palette of colors to choose from.

9. Overview of Swing Components
Summary:
Containers
Top-Level: JFrame, JOptinePane, JDialog, JFileChooser,JApplet,
General-purpose: JPanel, JScrollPane, JSplitPane
User input
JTextField, JPasswordField, JTextArea, JButton, JCheckbox,
JRadioButton, Jlist, JComboBox, JMenu, JMenuItem, JSlider,
JScrollBar
Information display
Non-editable: Jlabel, JProgressBar, Tool tips
Editable: Jtable, Texts, Jtree, JColorChooser

10. Outline
Outline:
Overview of Swing components
Layout management
Using Swing components
– Text input, Buttons, ComboBox, Menus, Dialogs

11. Layout Management
Layout management determines the size and
position of components.
Each container has a default layout manager.
Can be changed using the method: setLayout
Generally, need to set the layout manager of two
types of containers:
content panes (which use BorderLayout by
default) and
JPanels (which use FlowLayout by default).

12. • Types of Layout
– FlowLayout
– BorderLayout
– GridLayout
– BoxLayout
– GridBagLayout
Layout Management

13. Layout Management
• Component size
– Default/natural minimum/preferred sizes
calculated by the LayoutManager interface, which
is implemented by all layout management classes
• Dimension minimumLayoutSize(Container parent)
• Dimension preferredLayoutSize(Container parent)
– Can be changed using methods of JComponent
• voidsetMaximumSize(Dimension maximumSize)
• voidsetMinimumSize(Dimension minimumSize)
• voidsetPreferredSize(Dimension preferredSize)

14. Flow Layout
FlowLayout class
FlowLayout arranges components in a left-to-right flow, much like
lines of text in a paragraph.
Components sized at their preferred size.
If the horizontal space in the container is too small,
FlowLayout uses multiple rows.
Within each row, components are centered (the default), left-
aligned, or right-aligned as specified when the FlowLayout is
created.
Default layout manager of JPanel : typically used to arrange buttons
in a panel

15. Example: FlowWindow.java
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());
contentPane.add(new JButton("Button 1"));
contentPane.add(new JButton("2"));
contentPane.add(new JButton("Button 3"));
contentPane.add(new JButton("Long-Named Button 4"));
contentPane.add(new JButton("Button 5"));
Flow Layout

16. FlowLayout class constructors:
FlowLayout( int align, int hgap, int
vgap)
1. align: FlowLayout.LEFT,
FlowLayout.CENTER, FlowLayout.RIGHT
2. hgap: horizontal gap in pixels between components
3. vgap: vertical gap in pixels between components
FlowLayout( int align)
FlowLayout( )
Flow Layout

17. Border Layout
• BorderLayout:
– Has five areas
• Specify area for a component using one of the constants: NORTH, SOUTH,
EAST, WEST, and CENTER.
– Size of components determined by
• Their preferred sizes and the constraints of the container's size.
• The NORTH and SOUTH components may be stretched horizontally; the
EAST and WEST components may be stretched vertically; the CENTER
component may stretch both horizontally and vertically to fill any space
left over.
– Default for contentPane

18. Container contentPane = getContentPane();
//Use the content pane's default BorderLayout.
//contentPane.setLayout(new BorderLayout());
unnecessary
contentPane.add(new JButton("Button 1 (NORTH)"),
BorderLayout.NORTH);
contentPane.add(new JButton("2 (CENTER)"),
BorderLayout.CENTER);
contentPane.add(new JButton("Button 3 (WEST)"),
BorderLayout.WEST);
contentPane.add(new JButton("Long-Named Button 4
(SOUTH)"),BorderLayout.SOUTH);
contentPane.add(new JButton("Button 5 (EAST)"),
BorderLayout.EAST);
// BorderWindow.java

19. BorderLayout class constructors:
BorderLayout( int hgap, int vgap)
1. hgap: horizontal gap in pixels between
components
2. vgap: vertical gap in pixels between components
BorderLayout( )
Border Layout

20. Grid Layout
GridLayout: places components in a grid of cells.
Each component takes all the available space within
its cell. Each cell is exactly the same size.
Number of columns ignored when number of rows
set to non-zero
Example:

21. Container contentPane = getContentPane();
contentPane.setLayout(new GridLayout(0,2));
//construct an instance of GridLayout that has two
// columns and as many rows as necessary.
contentPane.add(new JButton("Button 1"));
contentPane.add(new JButton("2"));
contentPane.add(new JButton("Button 3"));
contentPane.add(new JButton("Long-Named Button 4"));
contentPane.add(new JButton("Button 5"));
// GridWindow.java

22. GridLayout class constructors:
GridLayout(int rows, int columns,
int hgap, int vgap)
1. hgap: horizontal gap in pixels between
components
2. vgap: vertical gap in pixels between components
GridLayout(int rows, int columns )
Grid Layout

23. Box Layout
• BoxLayout: places components in a single row or column
– Attempt to arrange components at their preferred widths (for
horizontal layout) or heights (for vertical layout).
• For a horizontal layout, if not all the components are the same height,
BoxLayout attempts to make all the components as high as the highest
component.
• For a vertical layout, BoxLayout attempts to make all components in the
column as wide as the widest component. If that fails, it aligns them
horizontally according to their X alignments.

24. Box Layout
• Instead of using BoxLayout directly, many programs use the
Box class.
• The Box class is a lightweight container that uses a BoxLayout.
• It also provides handy methods to help you use BoxLayout
well.
• Adding components to multiple nested boxes is a powerful
way to get the arrangement you want.

25. Box class methods: all static
Factory methods:
createHorizontalBox(),
createVerticalBox()
If all the components your Box contains have a fixed size, you
might want to use a glue component to control the components'
positions.
createHorizontalGlue(),
createVerticalGlue,
createGlue():
//push components as far away as possible
Box Layout

26. For a fixed amount of space between two components,
try using a strut & rigid area
createHorizontalStrut(int),
createVecticalStrut(int)
createRigidArea( Dimension )
//BoxLayoutTest.java
Box Layout

27. // construct the top horizontal box
JLabel label1 = new JLabel("Name:");
JTextField textField1 = new JTextField(10);
textField1.setMaximumSize(textField1.getPreferredSize());
Box hbox1 = Box.createHorizontalBox();
hbox1.add(label1);
// separate with a 10-pixel strut
hbox1.add(Box.createHorizontalStrut(10));
hbox1.add(textField1);
// construct the middle horizontal box
JLabel label2 = new JLabel("Password:");
JTextField textField2 = new JTextField(10);
textField2.setMaximumSize(textField2.getPreferredSize());
Box hbox2 = Box.createHorizontalBox();
hbox2.add(label2);
// separate with a 10-pixel strut
hbox2.add(Box.createHorizontalStrut(10));
hbox2.add(textField2);

28. // construct the bottom horizontal box
JButton button1 = new JButton("Ok");
JButton button2 = new JButton("Cancel");
Box hbox3 = Box.createHorizontalBox();
hbox3.add(button1);
// use "glue" to push the two buttons apart
hbox3.add(Box.createGlue());
hbox3.add(button2);
// add the three horizontal boxes inside a vertical box
Box vbox = Box.createVerticalBox();
vbox.add(hbox1);
vbox.add(hbox2);
vbox.add(Box.createGlue());
vbox.add(hbox3);
Container contentPane = getContentPane();
contentPane.add(vbox, BorderLayout.CENTER);

29. GridBag Layout
GridBagLayout:
The most sophisticated, flexible layout manager the Java platform
provides.
It aligns components by placing them within a grid of cells, allowing
some components to span more than one cell.
The rows in the grid aren't necessarily all the same height;
similarly, grid columns can have different widths.

30. Layout Management
Hierarchy of containers for achieving better layout:
Containers inside other containers
Each has a potentially a different layout manager
Allows you to create sophisticated layout with simple
layout managers
//CombineTest.java

31. // create vertical box
Box b = Box.createVerticalBox();
// create top panel (FlowLayout)
JPanel p1 = new JPanel();
p1.add( new JButton("Button 1"));
p1.add( new JButton("2"));
p1.add( new JButton("Button 3"));
b.add(p1);
// create Scrollable text area
JTextArea t = new JTextArea(200, 50);
JScrollPane sp = new JScrollPane( t );
b.add(sp);
// create bottom panel (right-aligned FlowLayout)
JPanel p2 = new JPanel();
p2.setLayout( new FlowLayout( FlowLayout.RIGHT ));
p2.add( new JButton("OK"));
b.add( p2 );
Container cp = getContentPane();
cp.add( b ); //CombineTest.java

32. Borders for Components
JComponents can have borders
Create Border objects using static methods of
BorderFactory class:
createLineBorder, createMatteBorder,
createEmptyBorder createEtchedBorder, ….
Set border using the setBorder method of Jcomponent
Example: BorderTest.java
This example also demonstrate the use of
JRadioButton, which will be discussed later

33. public BorderFrame()
{
setTitle("BorderTest");
setSize(WIDTH, HEIGHT);
demoPanel = new JPanel();
buttonPanel = new JPanel();
group = new ButtonGroup();
addRadioButton("Lowered bevel",
BorderFactory.createLoweredBevelBorder());
addRadioButton("Raised bevel",
BorderFactory.createRaisedBevelBorder());
addRadioButton("Etched",
BorderFactory.createEtchedBorder());
addRadioButton("Line",
BorderFactory.createLineBorder(Color.blue));
addRadioButton("Matte",
BorderFactory.createMatteBorder(
10, 10, 10, 10, Color.blue));
addRadioButton("Empty",
BorderFactory.createEmptyBorder());

34. Border etched =
BorderFactory.createEtchedBorder();
Border titled = BorderFactory.createTitledBorder
(etched, "Border types");
buttonPanel.setBorder(titled);
Container contentPane = getContentPane();
contentPane.setLayout(new GridLayout(2, 1));
contentPane.add(buttonPanel);
contentPane.add(demoPanel);
}

35. public void addRadioButton(String buttonName, final Border b)
{
JRadioButton button = new JRadioButton(buttonName);
button.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
demoPanel.setBorder(b);
validate();
}
});
group.add(button);
buttonPanel.add(button);
}

36. Outline
Outline:
Overview of Swing components
Layout management
Using Swing components
– Text input, Buttons, ComboBox, Menus, Dialogs

37. Text Input
JTextField, JPasswordField: one line.
JTextArea: A multi-line area that displays plain
text.
JEditorPane: A text component to edit various kinds
of content, plain text, html, rtf.
Can be monitored using either CaretListener or
DocumentListener
Check Documentation of JTextComponent

38. • JTextField also produces ActionEvent
when ”return” is pressed.
• Let’s make use of this to write a program:
Text1.java.
• Next, show how to make it better using
DocumentListener (Text.java)
Text Input

39. Model-View-Controller Design Pattern
Separates a software component into three distinct
pieces: a model, a view, and a controller.

40. Model-View-Controller Design Pattern
• Model
– represents the state and low-level behavior of the component.
– manages the state and conducts all transformations on that state.
– system itself maintains links between model and views and notifies
the views when the model changes state.
– Example: ButtonModel
• Query internal state
• Manipulate internal state
• Add and remove event listeners
• Fire events

41. Model-View-Controller Design Pattern
• view:
– manages the visual display of the state represented by the model.
• controller
– manages user interaction with the model. It provides the mechanism
by which changes are made to the state of the model.
• Example: ButtonUI
– Paint
– Return geometric information
– Handle AWT events

42. Model-View-Controller Design Pattern
• The component class JButton acts as the glue, or scaffolding, that holds the MVC
triad together
• Programmers do not typically work with model and view/controller classes
directly
• Example about what you can do using MVC:
http://www.developer.com/java/ent/article.php/3336761

43. Text Input
Model for all text components, including TextField, JPasswordField,
JTextArea are described by Document Interface.
Text component generates DocumentEvents when its content is changed.
To listen to such events, register a DocumentListener with the text
component
textComponent.getDocument()
.addDocumentListener(listener);
Check Documentation of JTextComponent

44. Text Input
The DocumentListener has three methods
void insertUpdate(DocumentEvent e)
void removeUpdate(DocumentEvent e)
void changeUpdate(DocumentEvent e)
// Gives notification that an attribute or set of attributes
changed.
No adapter class.

45. class TextTestFrame extends JFrame
{ public TextTestFrame()
{ setTitle("TextTest");
setSize(WIDTH, HEIGHT);
Container contentPane = getContentPane();
DocumentListener listener =
new ClockFieldListener();
// add a panel with text fields
JPanel panel = new JPanel();
hourField = new JTextField("12", 3);
panel.add(hourField);
hourField.getDocument().addDocumentListener(listener);
minuteField = new JTextField("00", 3);
panel.add(minuteField);
minuteField.getDocument().addDocumentListener(listener);
contentPane.add(panel, BorderLayout.SOUTH);
// add the clock
clock = new ClockPanel();
contentPane.add(clock, BorderLayout.CENTER);
} //TextTest.java.

46. Text Input/JTextField
private class ClockFieldListener implements
DocumentListener
{
public void insertUpdate(DocumentEvent e)
{ setClock(); }
public void removeUpdate(DocumentEvent e)
{ setClock(); }
public void changedUpdate(DocumentEvent e) {}
}
}

47. Text Input/JTextField
class TextTestFrame extends JFrame
{ public TextTestFrame()
{ …}
public void setClock() // retrieving from both fields
{ int hours =
Integer.parseInt(hourField.getText().trim());
int minutes =
Integer.parseInt(minuteField.getText().trim());
clock.setTime(hours, minutes);
}
……
}
Will change clock without pressing “Return”

48. • Exercise:
– Re-write Text.java using CaretListener
Text Input/JTextField

49. Outline
Outline:
Overview of Swing components
Layout management
Using Swing components
– Text input, Buttons, ComboBox, Menus, Dialogs

50. Buttons
All button classes descend from AbstractButton
JButton: A common button.
JCheckBox: For “yes” or “no” input.
JRadioButton: For exclusive choices among a
group. If one button is pushed, all other buttons in the
group depressed.

51. JCheckBox
Use a check box to collect yes/no input. The user checks/ the box by
clicking inside it and turns off the check mark by clinking it again.
Check boxes need a label next to them to identify their purpose.
Bold = new JCheckBox(“Bold”);
Use the setSelected method to turn a check box on or off
Bold.setSelected(true);
The isSelected method then retrieves the current state of each check
box. It is false if unchecked; true if checked.
When the user clicks on a check box, an action event is triggered. As
always, you attach an action listener.
ActionListener listener = …
Bold.addActionListener(listener)

52. class CheckBoxFrame extends JFrame
{ public CheckBoxFrame()
{ ……
ActionListener listener = new ActionListener()
{ public void actionPerformed(Actionevent event)
{ int mode = 0;
if (bold.isSelected()) mode +=Font.BOLD;
if (italic.isSelected()) mode +=Font.ITALIC;
label.setFont(new Font(“Serif”, mode, FONTSIZE));
}
}
JPanel buttonPanel = new JPanel();
bold = new JCheckBox( "Bold");
bold.addActionListener(listener);
buttonPanel.add(bold);
italic = new JCheckBox("Italic");
italic.addActionListener(listener);
buttonPanel.add(italic);
getContentPane().add(buttonPanel, BorderLayout.South);
…} // CheckBoxTest.java

53. Buttons/Radio Buttons
Radio buttons group are groups of buttons in which
only one button at a time can be selected.
The Swing release supports radio buttons with the
JRadioButton and ButtonGroup classes
Example: Choosing pets
(RadioButtonDemo.java)

54. // Create the radio buttons.
JRadioButton birdButton = new JRadioButton(birdString);
birdButton.setMnemonic('b'); // Enable ALT+b
// this is to be used together with getActionCommand
birdButton.setActionCommand(birdString);
birdButton.setSelected(true); // birButton selected
JRadioButton catButton = new JRadioButton(catString);
catButton.setMnemonic('c');
catButton.setActionCommand(catString);
// Note catButton not selected
// dogButton, RabbitButton, PigButton

55. // Group the radio buttons.
ButtonGroup group = new ButtonGroup();
group.add(birdButton);
group.add(catButton);
group.add(dogButton);
group.add(rabbitButton);
group.add(pigButton);
// now one of those buttons can be selected

56. // Register a listener for the radio buttons.
RadioListener myListener = new RadioListener();
birdButton.addActionListener(myListener);
catButton.addActionListener(myListener);
...
class RadioListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
picture.setIcon(new ImageIcon("images/“
+ e.getActionCommand()
+ ".gif"));
}
Get this string set by
setActionCommand
images/cat.gif
images/bird.gif
…

57. Outline
Outline:
Overview of Swing components
Layout management
Using Swing components
– Text input, Buttons, ComboBox, Menus, Dialogs

58. JComboBox
A JComboBox looks like a text field with an
arrow next to it. If you click on the arrow,
the list of possible values is displayed.
If the Jcombobox is set to be editable, then
you can edit the current selection as if it
was a text field.
Only one item can be selected at a time.
You can retrieve it by calling:
getSelectedItem method.
Add the choice items to the end of the list
with the addItem method.

59. JComboBox
Insert new items anywhere in the list with the insertItemAt :
faceCombo.insertItemAt(“Monospaced”, 0) //add at head
Remove items at run time by using removeItem or removeItemAt
faceCombo.removeItem(“Monospaced”);
faceCombo.removeItemAt(0); // remove first item
or
removeAllItems to remove all items at once
When an item is selected, the combo box generates an ActionEvent.
Call getSource on the event to get a reference to the combo box that
sent the event. Then call getSelectedItem to retrieve the selected
item.
//see ComboBoxTest.java

60. class ComboBoxFrame extends JFrame
{
public ComboBoxFrame()
{ setTitle("ComboBoxTest");
setSize(WIDTH, HEIGHT);
Container contentPane =
getContentPane();
// add the sample text label
label = new JLabel(
"The quick brown fox jumps over the lazy dog.");
label.setFont(new Font("Serif", Font.PLAIN, DEFAULT_SIZE));
contentPane.add(label, BorderLayout.CENTER);
// make a combo box and add face names
faceCombo = new JComboBox();
faceCombo.setEditable(true);
faceCombo.addItem("Serif");
faceCombo.addItem("SansSerif");
faceCombo.addItem("Monospaced");
faceCombo.addItem("Dialog");
faceCombo.addItem("DialogInput");

61. // the combo box listener changes the label font to the
// selected face name
faceCombo.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
label.setFont(new Font(
(String)faceCombo.getSelectedItem(),
Font.PLAIN, DEFAULT_SIZE));
}
});
//add combo box to a panel at the frame's souther
JPanel comboPanel = new JPanel();
comboPanel.add(faceCombo);
contentPane.add(comboPanel, BorderLayout.SOUTH);
}

62. Outline
Outline:
Overview of Swing components
Layout management
Using Swing components
– Text input, Buttons, ComboBox, Menus, Dialogs

63. Menus
Inheritance hierarchy of menu-related classes.
A menu bar contains one or more menus, placed onto a
frame.
A menu contains one or more menu items, which can be
menus themselves.

64. Menus/Creating Menus
1. Create JMenus
2. Create JmenuItems and associate
Actions with them
3. Add those JmenuItems to the Jmenu
4. When user selects a JmenuItem , an
Action is triggered.
5. Create a JMenuBar and place it onto a
frame
6. Add the JMenus to the JMenuBar

65. public class MenuTest extends JFrame …
{ public MenuTest()
{ …
JMenu fileMenu = new JMenu("File");
JMenuItem newItem = fileMenu.add(new TestAction("New"));
JMenuItem openItem = fileMenu.add(new TestAction(“Open”));
JMenuItem saveItem = fileMenu.add(new TestAction("Save"));
JMenuItem saveAsItem =fileMenu.add(new TestAction("Save As"));
….
JMenuBar mbar = new JMenuBar();
setJMenuBar(mbar); // add menu bar to the frame
menuBar.add(fileMenu);
menuBar.add(editMenu);
menuBar.add(helpMenu);
….
}
//MenuTest.java

66. Menus/Mnemonics and Accelerators
Keyboard Mnemonics are set by using setMnemonic
method
fileMenu.setMnemonic('F');
openItem.setMnemonic('O');
Accelerators are keyboard shortcuts (CTR+S, CTR+O)
openItem.setAccelerator
(KeyStroke.getKeyStroke(KeyEvent.VK_O,
InputEvent.CTRL_MASK));
saveItem.setAccelerator
(KeyStroke.getKeyStroke(KeyEvent.VK_S,
InputEvent.CTRL_MASK));

67. Menus/Menu Item Events
When user selects a menu item, an Action is triggered.
class TestAction extends AbstractAction
{
public TestAction(String name){super(name);}
public void actionPerformed(ActionEvent event)
{
System.out.println(getValue(Action.NAME) +
“ selected.”);
}
}

68. Menus/Menu Events
When user selects a menu, an MenuEvent is triggered.
MenuListener interface has three method
void menuSelected(MenuEvent )
// called before display menu
void menuDeselected(MenuEvent )
void menuCanceled(MenuEvent )
// called before menu selection is canceled, e.g.
// by clicking outside menu

69. Menus/Enable & Disabling Menu Items
Do this with setEnabled method.
saveItem.setEnabled( false);
saveAsItem.setEnabled( true );
Good time to enable and disable menu items: right before displaying, i.e.
within MenuListener
private class FileMenuListener implements MenuListener
{ …
public void menuSelected(MenuEvent evt)
{ saveItem.setEnabled(!readonlyItem.isSelected());
saveAsItem.setEnabled(!readonlyItem.isSelected());
}
This enables or disables saveItem and saveAsItem depending on
whether readonlyItem is selected.

70. Menus
Can have submenus, menu within menu. Inheritance
hierarchy of menu-related classes.
Can have check boxes, radio buttons as menu items
(JCheckBoxItem, JRadioButtonItem)
Can have popup menus.
MenuTest.java

71. Outline
Outline:
Overview of Swing components
Layout management
Using Swing components
– Text input, Buttons, ComboBox, Menus, Dialogs

72. Dialogs
Classes for specific dialogs
ProgressMonitor
JColorChooser
JFilerChooser
Class for standard dialogs
JOptionPane
Class for custom dialogs
JDialog

73. Dialogs
Every dialog box is a dependant of a parentComponent (frame).
parentComponent determines location of dialog box.
When that parentComponent is destroyed, so are its dependent
dialogs.
modal dialog box, when visible, blocks user input to all other windows
in the program. The dialogs that JOptionPane provides are modal.
A modeless dialog box lets the user enter information in both the
dialog box and the remainder of the application.
To create a modeless dialog, you must use the JDialog class
directly.
JDialog is a subclass of the AWT java.awt.Dialog
Using JDialog directly is very similar to using JFrame directly.

74. Option Dialogs
Commonly used methods of
JOptionPane
ShowMessageDialog
Show a message and wait for user
to click OK
ShowConfirmDialog
Show a message and get a
confirmation(Yes/No/Cancel)
ShowOptionDialog
Show a message and get a user
option from a set of options.
ShowInputDialog
Show a message and get one line
of user input.
//show DialogTest.java

75. Option Dialogs
Every Dialog has: an icon, a message , one or more option buttons.
icon type: ERROR_MESSAGE, INFORMATION_MESSAGE, WARNING_MESSAGE,
QUESTION_MESSAGE, PLAIN_MESSAGE
Message can be:
A String: Draw the string
Icon: Show the icon
Component: Show the component
Object[]: Show all objects in the array, stacked on top of each other.
Option buttons are:
DEFAULT_OPTION
YES_NO_OPTION
YES_NO_CANCEL_OPTION
OK_CANCEL_OPTION
Return value: An integer representing the chosen option
or a string that the user supplied or selected

76. Step to Create Option Dialogs
1. Choose the dialog type (message, confirmation, option or input),
2. Choose the icon(error, information, warning, question, none or custom).
3. Choose the message (string, icon, custom component, or a stack of
them).
4. For a confirmation dialog, choose the option type (default, yes/No,
Yes/No/Cancel, or OK/Cancel).
5. For an option dialog, choose the options (strings, icons, or custom
components ) and the default option.
6. For an input dialog, choose between a text field and a combo box.
7. Locate the appropriate method to call in the JOptionPane API.

77. Creating Dialogs
You can also create a dialog box by deriving a class from JDialog:
1. In the constructor of your dialog box, call the constructor of the base class
JDialog. You will need to tell it the owner frame (the frame window over
which the dialog pops up), the title of the dialog frame, and a Boolean flag to
indicate if the dialog box is modal or modeless.
2. Add the user interface components to the dialog box.
3. Add the event handlers.
4. Set the size for the dialog box.
//DialogTest.java

78. Data Exchange
The most common reason to put up a dialog box is to get information
from the user.
Your dialog box should provide methods to set default data:
public void setUser(User u)
{
username.setText(u.getName());
}
Then you can show the dialog such as the following:
boolean showDialog()
{
ok = false;
show();
return ok; //OK button sets the ok flag to true
}

79. Data Exchange
You should test the return value of the showDialog. If it is true, then
you can retrieve the user input by:
Public User getUser()
{
return new User (username.getText(),
password.getPassword());
}

80. private class ConnectAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
// if first time, construct dialog
if (dialog == null)
dialog = new PasswordChooser();
// set default values
dialog.setUser(new User("yourname", null));
// pop up dialog
if(dialog.showDialog(DataExchangeFrame.this, "Connect"))
{
// if accepted, retrieve user input
User u = dialog.getUser();
textArea.append(
"user name = " + u.getName() + ", password = "
+ (new String(u.getPassword())) + "n");
}
}
} //DataExchangeTest.java