The document discusses event handling in Java. It defines an event as a user action and describes how the Java runtime notifies programs of events instead of programs actively waiting for the events. It describes low-level events like keyboard and mouse events, and semantic events specific to components. It outlines the class hierarchies for different event types and describes the listener interfaces and their methods for responding to events.

1. Core Java
Debasish Pratihari
Event Handling :

Event : An event describe in sufficient details, a
particular user action

Instead the program takes care of collecting the
event, the java run-time notifies the program
about the event.

Program that handles user action in this fashion
is called event-driven programming.
System View of Event Handling
Key Strokes, Mouse Actions
Operating System
Java Run-Time
Event
Handlers
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Event
Handlers
Event
Handlers
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Event
Handlers
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2. Core Java
Debasish Pratihari
Event Types

Low-level Events
o These are events that are arises from the
keyboard or from mouse.

Semantic Events
o These are specific component-related
events
Low –level Event :
Event
Description
FocusEvent
MouseEvent
KeyEvent
WindowEvent
ComponenetEvent
ContainerEvent
Generated when a component gets or loses
input focus.
Generated when the mouse is dragged,
moved, clicked, pressed or released ; also
generated when the mouse enters or exits
a component.
Generated when input is received from the
keyboard.
Generated when a window is activated,
closed, deactivated, deiconified, iconified,
opened or quit.
Generated when a component is hidden,
moved, resized, or became visible.
Generated when a component is added to
or removed from a container.
Relationship Among classes
EventObject
java.util
AWTEvent
java.awt
ContainerEvent
ComponentEvent
WindowEvent
MouseEvent
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InputEvent
FocusEvent
KeyEvent
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3. Core Java
Debasish Pratihari
Semantic Events :
Event
ActionEvent
ItemEvent
AdjustEvent
Description
Generated when a button is pressed, a
list item is double-clicked, or a menu
item is selected.
Generated when a check box or list item
is clicked, choice selection is made or a
checkable menu item is selected or
deselected.
Generated on actions on a scrollbar.
Relationship among classes :
EventObject
AWTEvent
ActionEvent
ItemEvent
java.util
java.awt
TextEvent
AdjustmentObject
Listener Interfaces and their Methods:


ActionListener interface:
public abstract void actionPerformed(ActionEvent
e)
AdjustmentListener interface:
public abstract void adjustmentValueChanged(AdjustmentEvent e)


FocusListener interface:
public abstract void focusGained(FocusEvent e)
public abstract void focusLost(FocusEvent e)
ItemListener interface:
public abstract void itemStateChanged(ItemEvent e)
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4. Core Java

Debasish Pratihari
KeyListener interface:
public abstract void keyPressed(KeyEvent e)
public abstract void keyReleased(KeyEvent e)
public abstract void keyTyped(KeyEvent e)

MouseListener interface:
public abstract void mouseClicked(MouseEvent e)
public abstract void mouseEntered(MouseEvent e)
public abstract void mouseExited(MouseEvent e)
public abstract void mousePressed(MouseEvent e)
public abstract void mouseReleased(MouseEvent e)

MouseMotionListener interface
public abstract void mouseDragged(MouseMotionEvent e)
public abstract void mouseMoved(MouseMotionEvent e)

WindowListener interface:
25%
public abstract void windowActivated(WindowEvent
public
public
public
public
public
public

abstract
abstract
abstract
abstract
abstract
abstract
void
void
void
void
void
void
e)
windowClosed(WindowEvent e)
windowClosing(WindowEvent e)
windowDeactivated(WindowEvent e)
windowDeiconified(WindowEvent e)
windowIconified(WindowEvent e)
windowOpened(WindowEvent e)
TextListener interface:
public abstract void textValueChanged(TextEvent

e)
ComponentListener interface:
public abstract void componentHidden(ComponentEvent e)
public abstract void componentMoved(ComponentEvent e)
public abstract void componentResizes(ComponentEvent e)
public abstract void componentShown(ComponentEvent e)

ContainerListener interface:
public abstract void componentAdded(ContainerEvent e)
public abstract void componentRemoved(ContainerEvent e)
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