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Lecture 18


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Notes on core java

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Lecture 18

  1. 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 Lecture/core/event/18 Event Handlers Event Handlers Page #1 Event Handlers feel the Technology…
  2. 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 Lecture/core/event/18 InputEvent FocusEvent KeyEvent Page #2 feel the Technology…
  3. 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) Lecture/core/event/18 Page #3 feel the Technology…
  4. 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) Lecture/core/event/18 Page #4 feel the Technology…