Richard's J2SE Day 9 Working with Swing

(P233)
Swing = a set of classes
Metal = user-interface style

• Frames = windows include a title bar and menu bar, + maximize, minimize and close buttons
• Containers = interface elements that can hold other components
• Buttons = clickable regions with text or graphics
• Labels = text or graphics
• Text field and text areas
• Drop-down list
• Check boxes and radio buttons
  

Creating an Application (P234)
import javax.swing.*;
Before components can be displayed, they must be added to a container.

Creating and Interface (P235)
One way to create = to make the interface a subclas of JFrame
A few things to do in the constructor method of the class:

• Call a constructor
• Set the size of the frame's window in pixels
• Decide what to do if the user close the window
• Display the frame

JFrame class has two constructors: JFrame() and JFrame(String)

SetSize(int,int) or SetSize(Dimension) to set up a frame's size
Or fill the frame with omponents and call the pack() method

Make frames visible by calling the show() method or setVisible(boolean)
to hide a frame, hide() method or setVisible(false)

Default position is in the upper lefe corner of the computer desktop, to specify a different location, call the setBounds(int, int, int, int) => first 2 arguments: upper left corner + width and height

The normal behavior when a frame is closed is for the application to keep running. To change this, call setDefaultCloseOperation() method with one of four static variables

• EXIT_ON_CLOSE
• DISPOSE_ON_CLOSE
• DO_NOTHING_ON_CLOSE
• HIDE_ON_CLOSE

Developing a Framework (P237)
(P238) SimpleFrame.java

If you have not displayed the frame when it was constructed, you could call sf.setVisible(true) in the main() method to display the frame represented by sf.

(P239) SimpleWindow.java

Closing a Window (P240)
The window must be monitored to see whether the user has done anything to close it, such as clicking a title bar close button. It requires the use of event-handling classes (Day 12).
All event-handling classes belong to the java.awt.event package.

To monitor a window in a user interface, must do 3 things:

• Create an objec to monitor
• Implement an interface in the objects that handles each way the window can change
• Associate the window with your user interface

A window can be monitored by an object that implements the WindowListener interface.
A class must include all the methods in the interface. Classes that support WindowListener must have the following seven methods.

• windowActivated()
• windowDeactivated()
• windowClosed()
• windowClosing()
• windowOpened()
• windowIconified()
• windowDeiconified()

Another class in the java.awt.event package, WindowAdapter, implements this interface with seven empty methods that do nothing. By creating a subclass of WindowAdapter, you can override methods pertaining to the user interaction events that you want to deal with.
(P241) ExitWindow.java for other objects to associate it by calling addWindowListener() method
(P242) ExitFrame.java to use ExitWindow object previsouly created

Creating a Component (P242)
container classes = JFrame, JWindow
event-handling classes = WindowAdapter
interface component class = JButton

A Swing button can feture a text label, a graphical icon or a combination of both...
Constructor methods:

• JButton(String);
• JButton(Icon);
• JButton(String, Icon);

Adding Components to a Container (P243)
Add a component to a container, add(Component) method
Ordinarily, components are added to the container's content pane.
1. Create a panel
2. Add components to the panel using its add(Component) method
3. Call setContentPane(Container) with the pane as an argument

(P244) Buttons.java => Frame > Pane > Buttons

Working with Components (P245)
Swing offers two dozens different user interface components. All have common superclass, javax.swing.JComponent.

• setEnabled(boolean) = enables / disables component
• isEnable(boolean) = check if enabled
• setVisible(boolean) = works for all components
• setSize(int, int) or setSize(Dimension)
• getSize() returns Diemnsion object
• setText(), getText(), setValue(), getValue()

Image Icons (P245)
Swing supports ImageIcon objects on buttons and other components in which a label can be provided.
P246 Icons.java

Labels (P247)
User component that contains text, an icon, or both.
Constructors:

• JLabel(String)
• JLabel(String, int) - text and alignment (static class variables of the SwingConstants interface: LEFT, CENTER, RIGHT)
• JLabel(String, Icon, int)

Text Fields (P248)
User can enter and modify text through the keyboard = JTextField Class
Constructors:

• JTextField() = empty text field
• JTextField(int) = specified width
• JTextField(String, int) = specified text and width

setEditable(boolean), isEditable(), setText(String), getText(), getSelectedText()
JPasswordField class = a subclass of JTextField

Text Areas (P249)
more than one line of input = JTextArea class
Constructors:

• JTextArea(int, int) = rows and columns
• JTextArea(String, int, int) = specified text, rows and columns

getText(), getSelectedText(), setText(String), append(String), insert(String, int), setLineWrap(boolean), setWrapStyleWord(boolean)

(P250) Form.java

Scrolling Panes (P251)
Text areas do not include scrollbars.
Swing introduces a new container that can be used to hold any component that can be scrolled: JScrollPane.
Constructors:

• JScrollPane(Component) = scrolling pane contains the specified component
• JScrollPane(Component, int, int) = with vertical and horizontal scrollbar configuration

Static class variables of the ScrollPaneConstants interface

• VERTICAL_SCROLLBAR_ALWAYS
• VERTICAL_SCROLLBAR_AS_NEEDED
• VERTICAL_SCROLLBAR_NEVER

Scrollbars (P251)
components that enable a part of a large display to be selected for viewing. often used on text areas.
Some Swing components have built in scrollbar functionality, including scrolling panes and lists. You can also create a scrollbar by itself.
Constructors:

• JScrollBar(int) = with specified orientation
• JScrollBar(int, int, int, int, int) = specified orientation (HORIZONTAL or VERTICAL), starting value, scroll box size (default 10 lines), min value (default 0), max value (default 100)

Check Boxes and Radio Buttons (P252)
2 possible values: selected or not selected
JCheckBox and JRadioButton classes

• setSelected(boolean)
• isSelected()

Constructors:

• JCheckBox(String)
• JCheckBox(String, boolean)
• JCheckBox(Icon)
• JCheckBox(Icon, boolean)
• JCheckBox(String, Icon)
• JCheckBox(String, Icon, boolean)

JRadioButton class has constructors with the same arguments and functionality.
To organise several radio buttons into a group, allowing only one to be selected, create a ButtonGroup class object:

(P254) ChooseTeam.java

Drop-Down Lists and Combo Boxes (P255)
Swing class JComboBox can be used to create drop-down lists and combo boxes
Drop-down lists = a single item to be picked
Combo boxes = drop-down lists with a extra feature: a text field

Create a drop-down list

• JComboBox() constructor is used with no arguments
• addItem(Object) method

If the componet's setEditable() method is called with true as an argument, it becomes a combo box.
JComboBox() class methods:

• getItemAt(Int) - return text of the list item at position speficied (first = 0, second = 1 etc)
• getItemCount() - return number of items
• getSelectedIndex()
• setSelectedIndex(int)
• setSelectedIndex(Object)
• setMaximumRowCount(int) - set the number of rows in the combo box that are displayed at one time

(P256) Expiration.java

(P260) Exercise
VCRControls.java