Welcome Back!!!
Advanced Java Programming
CSE 7345/5345/ NTU 531
Session 7
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Steven Holzner,
IBM Corp
Office Hours:
by appt
3:30pm-4:30pm
SIC 353
Chantale
Laurent-Rice
Welcome Back!!!
trice75447@aol.com
claurent@engr.smu.edu
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Steven Holzner,
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Short review
Packages
• In Java, each class is defined in a single file called
ClassName.java.
• A package is a name for a set of related classes,
• Java uses package names to locate classes at compiletime and at runtime.
• Packages can be seen as some kind of libraries in which
the classes are grouped.
• The difference is that packages provide an additional
scope.
• Each class file must belong to a package:
• Example:
• Package dpack;
• Package java.awt.event;
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Packages con’t
• If no package is given, the class is placed in
a default package with no name.
• A compilation unit (a file) declares one or
more classes. It is a file that may contain
several class declarations. It is used as an
input for the java Compiler (javac) which
outputs a series of class files (bytecodes).
• There is a class file for each class in the
compilation unit.
• At the most one class is declared public.
Example:
Source code: ClassName.java hello.java
Bytecode: className.class hello.class
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Packages con’t
• To use the classes, one or more
modules in a program can import the
entire package with the declaration,
such as
import graphics.*;
• The asterisk indicates to the
compiler that it should import all
classes in the graphics package.
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Standard packages
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Java.appletJava.awtJava.awt.*-
provides the means to create applet
provides class-based GUI with windows
have subpackages such as java.awt,color,
java.awt.font, and java.awt.image
Java.beansprovides basic elements for JavaBeans
Java.ioprovides I/O
Java.langwrapper classes such as: Char, int, Double,
String and StringBuffer
java.mathmath programmers
Java.netnetwork, socket handler, internet utility classes
Java.rmiRemote Method Invocation provide support for
distributed code controlled by remote interface
Java.security- implements security, encryption keys, and
certificates
Java.sqlimplements of Structured Query Language database fields
types and methods
Java.textprovide parsers and formatters
Java.utilJava Application and applet (Random class, Collection, list,
Set) packages container class.
Java.util.jar- subpackage w/I java.util.
Java.util.zip- subpackage for .zip file compression format.
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Packages con’t
• To import just one class:
import graphics.Rectangle;
• It is not correct to import the package itself:
import graphics;
• Some packages provide one or more subpackages,
such as java.util.jar, a subpackage of java.util.
• Importing a package does not import any
subpackages.
• You must do that explicitly using statements like
these:
• Import java.utils.*;
• Import java.utils.jar.*;
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Small Quiz
• What happen if you tried to compile and run
the following code?
1. public class EqualsTest{
2.
public static void main(String[] args){
3.
Long L = new Long( 7 );
4.
5.
6. }
7. }
if( L.equals( 7L))
System.out.println(“Equal”);
else System.out.println(“Not Equal”);
a.
b.
c.
d.
The program would compile and print “Equal”
The program would compile and print “Not Equal”.
The compiler would object to line 4.
A runtime cast error would occur at line 4.
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Small Quiz
C.
qualsTest.java:5: cannot resolve symbol
symbol : method equals (long)
location: class java.lang.Long
if( L.equals( 7L))
^
1 error
• The compiler knows that the equals method takes
an Object rather than a primitive as input.
Because the compiler does not compile answer a, b,
d are incorrect.
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Small Quiz
• What happen if you tried to compile and run
the following code?
1. public class EqualsTest{
2.
public static void main(String[] args){
3.
Object A = new Long ( 7 );
4.
Long L = new Long( 7 );
5.
6.
7. }
8. }
if( A.equals( L ))
System.out.println(“Equal”);
else System.out.println(“Not Equal”);
a.
b.
c.
d.
The program would compile and print “Equal”
The program would compile and print “Not Equal”.
The compiler would object to line 5.
A runtime cast error would occur at line 5.
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Small Quiz
a.
• Because the Long object created in line 3
does not lose its identity when cast to
Object A, so the equals method knows the
class is correct and compares the values.
• Answer c, d, do not occur because this is
the correct form for comparing objects
with the equals method. Therefore, they
are incorrect.
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interface
What compile-time error is generated for the following program?
interface B{
void display();
}
class D1{
}
class D2 implements B{
public void display() {
System.out.println("D2");
}
}
class D3 implements B {
public void display() {
System.out.println("D3");
}
}
class InterfaceRefVar{
public static void main(String[] args){
B b;
b = new D1();
b.display();
b = new D2();
b.display();
b = new D3();
b.display();
}
}
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interface
The line “b = new D1();” generates an error
because the types are incompatible for
assignment. Class D1 does not implements
interface B.
• C:\InterfaceRefVar.java:23: incompatible
types
• found : D1
• required: B
•
b = new D1();
•
^
• 1 error
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Chapter 10 Getting Started with GUI Programming
• GUI Class Hierarchy
• Frames
– Creating frames, centering frames, adding
components to frames
• Layout Managers
– FlowLayout, GridLayout, BorderLayout
• Drawing on Panels
– The paintComponent method
• Using Colors, Fonts, and Font Metrics
• Drawing Geometric Figures
– Lines, Rectangles, Ovals, Arcs, and Polygons
• Event-Driven Programming
– Event Source, Listener, Listener Interface
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AWT/JFC
• AWT was a powerful toolkit when introduced
– it was the original driving force behind Java’s
popularity
– is today’s standard , a limited implementation
– not designed to provide a serious, main UI
for the needs of many programmers.
• Now Swing, which has about four times the
number of user interface (UI) components as
the AWT
– Swing is part of the standard Java
distribution
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AWT (Optional)
AWTEvent
Font
FontMetrics
Object
Color
Graphics
Component
Container
Panel
Applet
Button
Window
Frame
Label
TextField
Dialog
TextComponent
List
TextArea
Choice
CheckBox
LayoutManager
CheckBoxGroup
Canvas
MenuComponent
Scrollbar
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MenuItem
MenuBar
Menu
FileDialog
Question?
• Is JFC and Swing the same?
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JFC
• Many programmer that that JFC and
Swing are the same thing, but that’s
not so; the JFC contains Swing and
quite a number of other items.
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What’s in JFC?
Swing- The large UI package
Cut and paste- Clipboard support
Accessibility features- Aimed at users with
disabilities.
The desktop Colors features- First
introduced in Java 1.1
Java2D- Improved color, image, and text
support
Printing- Originally enabled in Java 1.1
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Class
AbstractButton
ButtonGroup
What’s in Swing?
Description
Abstract superclass for Swing buttons
Encapsulates a mutually exclusive set
of buttons
ImageIcon
Encapsulates an icon
JApplet
The Swing version of Applet
JButton
The Swing push button class
JCheckBox
The Swing check box class
JComboBox
Encapsulates a combo box
JLabel
The Swing version of a label
JRadioButton
The Swing version of a radio button
JScrollPane
Encapsulates a scrollable window
JTable
Encapsulates a table-based control
JTextField
The Swing version of a text field
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JTree
Encapsulates
a tree-based control
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GUI Class Hierarchy (Swing)
Dimension
Font
Classes in the java.awt
package
LayoutManager
1
Heavyweight
FontMetrics
Object
Color
Panel
Applet
JApplet
Window
Frame
JFrame
Dialog
JDialog
Graphics
Component
Container
*
Swing Components
in the javax.swing package
JComponent
Lightweight
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.
JComponent
JCheckBoxMenuItem
AbstractButton
JMenuItem
JMenu
JButton
JRadioButtonMenuItem
JToggleButton
JCheckBox
JRadioButton
JEditorPane
JComponent
JTextComponent
JTextField
JPasswordField
JTextArea
JLabel
JList
JComboBox
JMenuBar
JPanel
JOptionPane
JScrollBar
JTabbedPane
JFileChooser
JPopupMenu
JSeparator
JSlider
JRootPane
JPane
JProgressBar
JToolBar
JSplitPane
JTable
JTree
JInternalFrame
JToolTip
JLayeredPane
JTableHeader
JColorChooser
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JScrollPane
JApplets
• Fundamental to Swing is the JApplet class,
which extends Applet.
• Applets that use Swing must be subclasses
of JApplet.
• JApplet is rich with functionality that is
not found in Applet.
• For Example:
• JApplet support various “panes”, such as
the content pane, the glass pane, and the
root pane.
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Frames
• 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 Frame class can be used
to create windows.
• For Swing GUI programs, use
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JFrame class to create
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UI Components
Frame
Pull-down Menus
Applet
Panel
User Interface
Components (UI)
Panel
Panel
User Interface
Components
User Interface
Components
Panel
Panel
User Interface
Components
User Interface
Components
Panel
Panel
Panel
Panel
UI
UI
UI
panel
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Pull-down Menus
Creating 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);
}
}
NOTE: You must have JDK 1.3 or higher to run
the slides.
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Run
Centering Frames
By default, a frame is
displayed in the upper-left
corner of the screen.
To display a frame at a
specified location, you can use
the setLocation(x, y) method in
the JFrame class.
This method places the upperleft corner of a frame at
location (x, y).
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Centering Frames, cont.
(0, 0)
Screen
(x, y)
Frame
getHeight()
screenHeight
getWidth()
screenWidth
Run
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Adding Components into a Frame
// Add a button into the frame
frame.getContentPane().add(
new JButton("OK"));
Run
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NOTE
The content pane is a subclass of
Container. The statement in the
preceding slide can be replaced by the
following two lines:
Container container =
frame.getContentPane();
container.add(new JButton("OK"));
You may wonder how a Container object
is
It O’Neil,
isSteven
created
when a
Liang,created.
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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.
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Kinds of Layout Managers
• FlowLayout (Chapter 10)
• GridLayout (Chapter 10)
• BorderLayout (Chapter 10)
• CardLayout (Chapter 12)
• GridBagLayout (Chapter 12)
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Example 10.1
Testing the FlowLayout Manager
The components are
arranged in the
container from left
to right in the
order in which they
were added. When
one row becomes
filled, a new row is
started.
Run
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FlowLayout Constructors
• public FlowLayout(int align, int hGap, int vGap)
Constructs a new FlowLayout with a specified alignment,
horizontal gap, and vertical gap. The gaps are the
distances in
pixel between components.
• public FlowLayout(int alignment)
Constructs a new FlowLayout with a specified alignment
and a default gap of five pixels for both horizontal and
vertical.
• public FlowLayout()
Constructs a new FlowLayout with a default
center alignment and a default gap of five pixels
for
both horizontal and vertical.
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Example 10.2
Testing the GridLayout Manager
The GridLayout manager arranges
components
in a grid (matrix) formation with the number
of
rows and columns defined by the constructor.
The components are placed in the grid from
left to right starting with the first row, then
the second, and so on.
Run
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GridLayout Constructors
• public GridLayout(int rows,
int columns)
Constructs a new GridLayout with the
specified number of rows and columns.
• public GridLayout(int rows, int
columns, int hGap, int vGap)
Constructs a new GridLayout with the
specified number of rows and columns,
along with specified horizontal and
vertical gaps between components.
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Example 10.3
Testing 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.
Run
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Example 10.3, cont.
Run
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Using Panels as Containers
• Panels act as smaller 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.
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Example 10.4 Testing Panel
This example uses panels to
organize components. The
program creates a user
interface for a Microwave
frame
oven.A textfield
p2
A button
12
buttons
p1
Run
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Drawing on Panels
JPanel can be used to draw graphics
(including text) and enable user interaction.
To draw in a panel, you create a
new class that extends JPanel and
override the paintComponent method
to tell the panel how to draw
things. You can then display
strings, draw geometric shapes,
and
view images on the panel.
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Drawing on Panels, cont.
public class DrawMessage extends JPanel {
/** Main method */
public static void main(String[] args) {
JFrame frame = new JFrame("DrawMessage");
frame.getContentPane().add(new DrawMessage());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE
);
frame.setSize(300, 200);
frame.setVisible(true);
}
/** Paint the message */
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("Welcome
toHolzner,
Java!", 40, 40);
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}
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Drawing on Panels, cont.
(0, 0)
x
(x, 0)
y
(0, y)
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(x, y)
NOTE
The Graphics class is an abstract class
for displaying figures and images on
the screen on different platforms.
The Graphics class is implemented on
the native platform in the JVM. When
you use the paintComponent method to
draw things on a graphics context g,
this g is an instance of a concrete
subclass of the abstract Graphics class
for the specific platform.
The Graphics class encapsulates the
platform details and enables you to
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draw
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NOTE
Whenever a component is displayed,
a Graphics object is created for
the component.
The Swing components use the
paintComponent method to draw
things.
The paintComponent method is
automatically invoked to paint the
graphics context when the
component is first displayed or
whenever the component needs to be
redisplayed.
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Invoking
super.paintComponent(g)
NOTE
To draw things, normally you
create a subclass of JPanel
and override its
paintComponent method to tell
the system how to draw.
In fact, you can draw things
on any GUI component.
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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);
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Setting Colors
You can use the following methods to set
the component’s background and foreground
colors:
setBackground(Color c)
setForeground(Color c)
Example:
setBackground(Color.yellow);
setForeground(Color.red);
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The Font Class
Font myFont = Font(name, style, size);
Example:
Font myFont = new Font("SansSerif ", Font.BOLD, 16);
Font myFont = new Font("Serif", Font.BOLD+Font.ITALIC, 12);
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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]);
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Setting Fonts
public void paint(Graphics g) {
Font myFont = new Font("Times", Font.BOLD, 16);
g.setFont(myFont);
g.drawString("Welcome to Java", 20, 40);
//set a new font
g.setFont(new Font("Courier", Font.BOLD+Font.ITALIC,
12));
g.drawString("Welcome to Java", 20, 70);
}
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The FontMetrics Class
public void paint(Graphics g) {
g.getFontMetrics(Font f); or
g.getFontMetrics();
}
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Get FontMetrics
• public int getAscent()
• public int getDescent()
• public int getLeading()
• public int getHeight()
• public int stringWidth(String str)
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Example 10.5
Using FontMetrics
• Objective: Display “Welcome to Java” in
SansSerif 20-point bold, centered in the
frame.
Run
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messagePanel
stringWidth
getHeight()
stringAscent
Welcome to Java
getWidth()
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Example 10.5, cont.
JPanel
JFrame
-char token
+getToken
MessagePanel
+setToken
+paintComponet
-xCoordinate: int
+mouseClicked
-yCoordinate: int
-centered: boolean
-message: String
-char token
1
1
+getMessage(): String
+getXCoordinate(): int
+getYCoordinate(): int
+isCentered(): boolean
+setMessage(message: String): void
+setXCoordinate(x: int): void
+setYCoordinate(y: int): void
+setCentered(centered: boolean): void
+paintComponent(g: Graphics): void
+getPerferredSize(): Dimension
+getMinimumSize(): Dimension
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+getToken
TestFontMetrics
+setToken
+paintComponet
+mouseClicked
Drawing Geometric Figures
• Drawing Lines
• Drawing Rectangles
• Drawing Ovals
• Drawing Arcs
• Drawing Polygons
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Drawing Lines
drawLine(x1, y1, x2, y2);
(x1 , y1)
(x2 , y2)
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Drawing Rectangles
• drawRect(x, y, w, h);
• fillRect(x, y, w, h);
(x, y)
h
w
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Drawing Rounded Rectangles
• drawRoundRect(x, y, w, h, aw, ah);
• fillRoundRect(x, y, w, h, aw, ah);
(x, y)
ah/2
aw/2
h
w
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Drawing Ovals
• drawOval(x, y, w, h);
• fillOval(x, y, w, h);
(x, y)
h
w
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Drawing Arcs
• drawArc(x, y, w, h, angle1, angle2);
• fillArc(x, y, w, h, angle1, angle2);
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Drawing Polygons
int[] x = {40, 70, 60, 45, 20};
int[] y = {20, 40, 80, 45, 60};
g.drawPolygon(x, y, x.length);
g.fillPolygon(x, y, x.length);
(x[0], y[0])
(x[1], y[1])
(x[3], y[3])
(x[4], y[4])
(x[2], y[2])
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Example 10.6
Drawing a Clock
• Objective: Use drawing and trigonometric
methods to draw a clock showing the
specified hour, minute, and second in a
frame.
Run
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Drawing Clock
xEnd = xCenter + handLength 
sin()
yEnd = yCenter - handLength 
cos()
Since there are sixty seconds
in one minute, the angle for
the second hand is
second  (2/60)
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Drawing Clock, cont.
xEnd = xCenter + handLength 
sin()
yEnd = yCenter - handLength 
The position
of the minute hand is
cos()
determined by the minute and
second. The exact minute value
comined with seconds is minute +
second/60. For example, if the time
is 3 minutes and 30 seconds. The
total minutes are 3.5. Since there are
sixty minutes in one hour, the angle
for the minute hand is
(minute + second/60) 
(2/60)
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Drawing Clock, cont.
xEnd = xCenter + handLength 
sin()
yEnd = yCenter - handLength 
cos()
Since one circle is divided into
twelve hours, the angle for the
hour hand is
(hour + minute/60 +
second/(60  60))) 
(2/12)
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IBM Corp
Event-Driven Programming
• Procedural programming is executed
in procedural order.
• In event-driven programming, code is
executed upon activation of events.
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IBM Corp
Events
• An event can be defined as a type of
signal to the program that something
has happened.
• The event is generated by external user
actions such as mouse movements,
mouse button clicks, and keystrokes, or
by the operating system, such as a
timer.
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IBM Corp
Event Information
• id: A number that identifies the event.
• target: The source component upon which the event
occurred.
• arg: Additional information about the source
components.
• x, y coordinates: The mouse pointer location when
a mouse movement event occurred.
• clickCount: The number of consecutive clicks for
the
mouse events. For other events, it is zero.
• when: The time stamp of the event.
• key: The key that was pressed or released.
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IBM Corp
Event Classes
EventObject
AWTEvent
ActionEvent
ContainerEvent
AdjustmentEvent
FocusEvent
ComponentEvent
InputEvent
ItemEvent
PaintEvent
TextEvent
WindowEvent
ListSelectionEvent
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IBM Corp
MouseEvent
KeyEvent
Selected User Actions
User Action
Clicked on a button
Changed text
Double-clicked on a list item
Selected or deselected an item
with a single click
Selected or deselected an item
Source
Object
Event Type
Generated
JButton
ActionEvent
JTextComponent
TextEvent
JList
ActionEvent
JList
ItemEvent
JComboBox
ItemEvent
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IBM Corp
The Delegation Model
EventObject
User
action
Generate
an event
Notify listener
Trigger an event
Source Object
Register a listener object
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IBM Corp
Listener Object
Event Handler
Selected Event Handlers
Event Class
Listener Interface
Listener Methods (Handlers)
ActionEvent
ItemEvent
WindowEvent
ActionListener
ItemListener
WindowListener
ContainerEvent
ContainerListener
actionPerformed(ActionEvent)
itemStateChanged(ItemEvent)
windowClosing(WindowEvent)
windowOpened(WindowEvent)
windowIconified(WindowEvent)
windowDeiconified(WindowEvent)
windowClosed(WindowEvent)
windowActivated(WindowEvent)
windowDeactivated(WindowEvent)
componentAdded(ContainerEvent)
componentRemoved(ContainerEvent)
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IBM Corp
Example 10.7
Handling Simple Action Events
• Objective: Display two buttons OK and
Cancel in the window. A message
is displayed on the console to
indicate which button is
clicked, when a button is
clicked.
Run
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Steven Holzner,
IBM Corp
Example 10.8
Handling Window Events

Objective: Demonstrate handling the window events.
Any subclass of the Window class can generate the
following window events: window opened, closing,
closed, activated, deactivated, iconified, and
deiconified. This program creates a frame, listens to
the window events, and displays a message to
indicate the occurring event.
Run
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IBM Corp
Example 10.9 Multiple Listeners for a Single Source

Objective: This example modifies
Example 10.7 to add a new listener
for each button. The two buttons
OK and Cancel use the frame class
as the listner. This example
creates a new listener class as an
additional listener for the action
events on the buttons. When a
button is clicked, both listeners
respond to the action event. Run
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Steven Holzner,
IBM Corp