The document discusses event handling in Java. It describes what events are, how event handling works using the delegation event model. It lists common event classes and their corresponding listener interfaces. It provides examples of using events and listeners to handle button clicks and key presses. It also discusses adapter classes that simplify creating event handlers.

1. Unit 5
Event Handling

2. Event Handling
 What is an event?
 What is event handling?

3. What is an event in applet?
 Change in the state of an object is
known as event i.e. event describes the
change in state of source.
 Events are generated as result of user
interaction with the graphical user
interface components.
 For example, clicking on a button,
moving the mouse, entering a character
through keyboard, selecting an item
from list, scrolling the page are the
activities that causes an event to

4. What is an event handling?
 Event Handling is the mechanism that
controls the event and decides what
should happen if an event occurs.
 Java Uses the Delegation Event
Model to handle the events.

5. Delegation Event Model
There are mainly three parts in delegation
event model.
 Events : An event is a change of state of
an object.
 Events Source : Event source is an
object that generates an event.
 Listeners : A listener is an object that
listens to the event. A listener gets notified
when an event occurs.

7. Event classes and Listener
interfaces
Event Class Description
Listener
Interface
ActionEvent Button, List, MenuItem, TextField ActionListener
MouseEvent
generated when mouse is
dragged, moved,clicked,pressed
or released also when the enters
or exit a component
MouseListener
KeyEvent
generated when input is
received from keyboard
KeyListener
ItemEvent
Choice, Checkbox,
CheckboxMenuItem, List
ItemListener
TextEvent TextArea, TextField TextListener

8. MouseWheelEven
t
generated when mouse
wheel is moved
MouseWheelListener
WindowEvent
generated when window is
activated, deactivated,
deiconified, iconified,
opened or closed
WindowListener
ComponentEvent
generated when component
is hidden, moved, resized or
set visible
ComponentEventListener
ContainerEvent
generated when component
is added or removed from
container
ContainerListener
AdjustmentEvent Scrollbar AdjustmentListener
FocusEvent
generated when component
gains or loses keyboard
focus
FocusListener

9. Event Listener interface Event Listener Methods
ActionListener actionPerformed(ActionEvent evt)
AdjustmentListener adjustmentValueChanged(AjustmentEvent evt)
ItemListener itemStateChanged(ItemEvent evt)
TextListener textValueChanged(TextEvent evt)
ComponentListener
componentHidden(ComponentEvent evt),
componentMoved(ComponentEvent evt),
componentResized(ComponentEvent evt),
componentShown(ComponentEvent evt)
ContainerListener
componentAdded(ContainerEvent evt),
componentRemoved(ContainerEvent evt)
FocusListener
focusGained(FocusEvent evt),
focusLost(FocusEvent evt)
KeyListener
keyPressed(KeyEvent evt),
keyReleased(KeyEvent evt),
keyTyped(KeyEvent evt)

10. MouseListener
mouseClicked(MouseEvent evt),
mouseEntered(MouseEvent evt),
mouseExited(MouseEvent evt),
mousePressed(MouseEvent evt),
mouseReleased(MouseEvent evt)
MouseMotionListener
mouseDragged(MouseEvent evt),
mouseMoved(MouseEvent evt)
WindowListener
windowActivated(WindowEvent evt),
windowClosed(WindowEvent evt),
windowClosing(WindowEvent evt),
windowDeactivated(WindowEvent
evt), windowDeiconified(WindowEvent
evt), windowIconified(WindowEvent
evt), windowOpened(WindowEvent
evt)

13. Lab Program: Factorial using
Appletimport java.applet.*;
import java.awt.event.*;
import java.awt.*;
/*<applet code="Factorial" width=500 height=500> </applet> */
public class Factorial extends Applet implements
ActionListener
{
Label L1,L2; TextField t1,t2; Button b1,b2;
public void init()
{
L1=new Label("Enter a value: "); L2=new Label("Result:");
t1=new TextField(10); t2=new TextField(10);
b1=new Button("Calculate"); b2=new
Button("Clear");
add(L1); add(t1); add(b1);
add(b2); add(L2); add(t2);
b1.addActionListener(this);
b2.addActionListener(this);

14. public void actionPerformed(ActionEvent ae)
{
int n=Integer.parseInt(t1.getText());
int fact=1;
if(ae.getSource()==b1)
{
if(n==0||n==1)
{ fact=1; t2.setText(String.valueOf(fact)); }
else
{
for(int i=1;i<=n;i++) fact=fact*i;
}
t2.setText(String.valueOf(fact));
}
else if(ae.getSource()==b2) { t1.setText(""); t2.setText("");
}
}
}

15. Adapter Class
 Java provides a special feature, called
an adapter class, that can simplify the
creation of event handlers in certain
situations.
 Adapter classes are useful when you
want to receive and process only
some of the events that are handled
by a particular eventlistener interface.

17. /*
<Applet Code="KeyDemo.class" Width="350" Height="250">
</Applet>
*/
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.applet.Applet;
public class KeyDemo extends Applet
{
String msg="";
private int _x=100,_y=150;
public void init()
{
setBackground(Color.pink);
addKeyListener(new KeyAdapter()
{
public void keyTyped(KeyEvent e)
{
msg="You Pressed: ";
msg+=e.getKeyChar();
repaint();
}
});
}
public void paint(Graphics g)
{
g.drawString(msg,_x,_y);
}
}

18. Java Programming
Unit 6

19. What is swing in Java
 Swing is a set of classes that provides
more powerful and flexible
components than are possible with the
AWT.
 In addition to components, such as
buttons, check boxes, and labels,
Swing supplies several exciting
additions, including tabbed panes,
scroll panes, trees, and tables.
 Unlike AWT, Java Swing provides
platform-independent and lightweight
components.

20. Java AWT Java Swing
AWT components are platform-
dependent.
Java swing components
are platform-independent.
AWT components
are heavyweight.
Swing components
are lightweight.
AWT doesn't support
pluggable look and feel.
Swing supports pluggable look
and feel.
AWT provides less
components than Swing.
Swing provides more powerful
components such as tables,
lists, scrollpanes, colorchooser,
tabbedpane etc.
AWT doesn't follows
MVC(Model View Controller)
model stores the data.
view creates the visual representation
controller deals with user interaction
and modifies the model and/or the
view.
Swing follows MVC.

22. JPanel : JPanel is Swing's version of AWT class
Panel and uses the same default layout, FlowLayout.
JPanel is descended directly from JComponent.
JFrame : JFrame is Swing's version of Frame and is
descended directly from Frame class. The component
which is added to the Frame, is refered as its Content.
JWindow : This is Swing's version of Window and
hass descended directly from Window class.
Like Windowit uses BorderLayout by default.
JLabel : JLabel descended from Jcomponent, and is
used to create text labels.
JButton : JButton class provides the functioning of
push button. JButton allows an icon, string or both
associated with a button.
JTextField : JTextFields allow editing of a single line
of text.

23. JApplet

24. Creating a JFrame
 There are two way to create a JFrame
Window.
 By instantiating JFrame class.
 By extending JFrame class.

25. Creating JFrame window by
Instantiating JFrame class
 Jfirst.java
 Jsecond.java

26. TextField
 The Swing text field is encapsulated
by the JTextComponent class, which
extends JComponent.
constructors are shown here:
 JTextField( )
 JTextField(int cols)
 JTextField(String s, int cols)
 JTextField(String s)
 Here, s is the string to be presented,
and cols is the number of columns in
the text field.

27. import java.awt.*;
import javax.swing.*;
/*
<applet code="JTextFieldDemo" width=300 height=50>
</applet>
*/
public class JTextFieldDemo extends JApplet {
JTextField jtf;
public void init() {
// Get content pane
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());
// Add text field to content pane
jtf = new JTextField(15);
contentPane.add(jtf);
}
}

28. Combo Boxes
 JComboxBox is a Swing component
that renders a drop-down list of
choices and lets the user selects one
item from the list.

29. JComboBox Constructors
JComboBox()Creates a JComboBox with a default data
model.
JComboBox(ComboBoxModel aModel)Creates a
JComboBox that takes its items from an existing
ComboBoxModel.
JComboBox(Object[] items)Creates a JComboBox that
contains the elements in the specified array.
JComboBox(Vector<?> items)Creates a JComboBox
that contains the elements in the specified Vector.

30. void actionPerformed(ActionEvent e)
void addItem(Object anObject)
Methods in JComboBox
void contentsChanged(ListDataEvent e)
String getActionCommand()
Object getItemAt(int index)
int getItemCount()
Object getSelectedItem()

31. Creating a new JComboBox component
JComboBox<String> comboLanguage = new JComboBox<String>();
comboLanguage.addItem("English");
comboLanguage.addItem(“Telugu");
comboLanguage.addItem(“Hindi");
comboLanguage.addItem(“Tamil");
comboLanguage.addItem(“Kannada");
String[] languages = new String[] {"English", “Telugu", “Hindi", “Tamil", “Kannada"};
JComboBox<String> comboLanguage = new JComboBox<String>(languages);
Vector<String> languages = new Vector<String>();
languages.addElement("English");
languages.addElement(“Telugu");
languages.addElement(“Hindi");
languages.addElement(“Tamil");
languages.addElement(“Kannada");
JComboBox<String> comboLanguage = new JComboBox<String>(languages);
myComboBox.setEditable(true);

32. JTabbedPane
 A component that lets the user switch between a
group of components by clicking on a tab with a
given title and/or icon.
 Constructors of JTabbedPane
 JTabbedPane(): which creates an empty
TabbedPane component using default tab
placement.
 JTabbedPane(int tabPlacement): creates an empty
TabbedPane with the specified tab placement such
as either of JTabbedPane.TOP,
JTabbedPane.BOTTOM, JTabbedPane.LEFT, or
JTabbedPane.RIGHT.
 JTabbedPane(int tabPlacement, int
tabLayoutPolicy) which creates an empty
TabbedPane with the specified tab placement and
specified tab layout policy.

33. public class JTabbedPaneDemo extends JPanel
{
public JTabbedPaneDemo()
{
ImageIcon icon = new ImageIcon("java-swing.JPG");
JTabbedPane jtbExample = new JTabbedPane();
JPanel jplInnerPanel1 = createInnerPanel("Tab 1 Contains Tooltip and
Icon");
jtbExample.addTab("One", icon, jplInnerPanel1, "Tab 1");
jtbExample.setSelectedIndex(0);
JPanel jplInnerPanel2 = createInnerPanel("Tab 2 Contains Icon
only");
jtbExample.addTab("Two", icon, jplInnerPanel2);
JPanel jplInnerPanel3 = createInnerPanel("Tab 3 Contains Tooltip and
Icon");
jtbExample.addTab("Three", icon, jplInnerPanel3, "Tab 3");
JPanel jplInnerPanel4 = createInnerPanel("Tab 4 Contains Text
only");
jtbExample.addTab("Four", jplInnerPanel4);
// Add the tabbed pane to this panel.
setLayout(new GridLayout(1, 1));

34. protected JPanel createInnerPanel(String text) {
JPanel jplPanel = new JPanel();
JLabel jlbDisplay = new JLabel(text);
jlbDisplay.setHorizontalAlignment(JLabel.CENTER);
jplPanel.setLayout(new GridLayout(1, 1));
jplPanel.add(jlbDisplay);
return jplPanel;
}
public static void main(String[] args) {
JFrame frame = new JFrame("TabbedPane Source
Demo");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
frame.getContentPane().add(new
JTabbedPaneDemo(),BorderLayout.CENTER);
frame.setSize(400, 125);
frame.setVisible(true);
}
}

35. Introduction to JDBC

36. What is JDBC?
 JDBC stands for Java Database
Connectivity, which is a standard Java
API for database-independent
connectivity between the Java
programming language and a wide
range of databases.

37. 44
Overview of Querying a
Database With JDBC

38. JDBC Driver
DatabaseDatabaseJDBC
driver
Java app Database
JDBC
calls
Database
commands
JDBC
driver
JDBC
driver
Inside the code, you make
calls using JDBC APIs
Software module that
translates JDBC calls to
SQL commands
 Is an interpreter that translates JDBC method calls
to vendor-specific database commands
 Implements interfaces in java.sql
 Can also provide a vendor’s extensions to the JDBC
standard

39. How to Make the Connection
1. Register the driver.
DriverManager.registerDriver (new
oracle.jdbc.driver.OracleDriver());
Class.forName(“oracle.jdbc.driver.OracleDriver”);
Or
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
}
catch(ClassNotFoundException ex) {
System.out.println("Error: unable to load driver class!");
System.exit(1);
}

40. How to Make the Connection
47
2. Connect to the DB
Connection conn = DriverManager.getConnection
(URL, userid, password);
Connection conn = DriverManager.getConnection
("jdbc:oracle:thin:@oracle.abc:1521:EMP",
"userid", "password");
In Oracle DB
Oracle username and pw

41. 48
Import java.sql package
Register the
driver
Establish
connection

42. Stage 2: Query the DB
49
 A Statement object sends SQL command to the database
 You need an active connection to create a JDBC statement
 Statement has methods to execute a SQL statement:
 executeQuery() for QUERY statements
 executeUpdate() for INSERT, UPDATE, DELETE

43. Stage 3: Process Results
50

44. Stage 4: Closing
51

45. How to Close
52

46. Example: Connect to Microsoft
SQL Server via JDBC
 System contains Microsoft JDBC Driver.
 JDBC database URL for SQL Server
◦ The syntax of database URL for SQL Server
is as follows:
◦ jdbc:sqlserver://[serverName[instanceNa
me]
[:portNumber]][;property=value[;property=val
ue]]
Where:
serverName: host name or IP address of machine on which SQL server is
running.
instanceName: name of the instance to connect to on serverName. The default
instance is used if this parameter is not specified.
portNumber: port number of SQL server, default is 1433.
property=value: specify one or more additional connection properties.

47. Register JDBC driver for SQL Server and establish connection
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
String dbURL =
"jdbc:sqlserver://localhostsqlexpress";
String user = “user4";
String pass = “pwd";
conn = DriverManager.getConnection(dbURL, user,
pass);

48. import java.sql.*;
public class Sqlselection {
public static void main(String[] args) {
try {
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
String userName = “user4";
String password = “pwd";
String url = "jdbc:sqlserver://localhostsqlexpress";
Connection con = DriverManager.getConnection(url, userName, password);
Statement s1 = con.createStatement();
ResultSet rs = s1.executeQuery("SELECT * FROM EMP");
String[ ] result = new String[20];
if(rs!=null) {
while (rs.next()) {
for(int i = 0; i <result.length ;i++) {
for(int j = 0; j <result.length;j++) { result[j]=rs.getString(i);
System.out.println(result[j]);
}
}
}
}
} catch (Exception e) { e.printStackTrace(); } } }