Delegation of event modelling in java
Delegation of Event Modelling
- Hi Students I am going to write Article on Delegation of Event Modelling in simplified Manner.
- When an event occurs we programmers has 3 options for handling events
1. Let it happen what ever happen(ignore event).
2. Let any other component manage the event.
*3. Let Delegate its handling to some other object called Listener.
According to delegation of event modeling,For example when a button click or option
Selected by user, Then Listener if we connected listen to the event, and then it invokes
A method called action performed.
Detailed Table for Event Modelling
CONTROL LISTENER METHODS AND EVENTS
Button Action Listener actionPerformed(ActionEvent e)
List Action Listener actionPerformed(ActionEvent e)
MenuItem Action Listener actionPerformed(ActionEvent e)
TextField Action Listener actionPerformed(ActionEvent e)
Checkbox ItemListener itemStateChanged(ItemEvent e)
Choice ItemListener itemStateChanged(ItemEvent e)
List ItemListener itemStateChanged(ItemEvent e)
Checkbox MenuItem ItemListener itemStateChanged(ItemEvent e)
DialogFrame WindowListener windowOpened(WindowEvent e)
DialogFrame WindowListener windowClosing(WindowEvent e)
DialogFrame WindowListener windowMinimized(WindowEvent e)
Scrollbar AdjustmentListener adjustmentValueChanged
(AdjustmentEvent e)
Canvas MouseListener mousePressed(MouseEvent e)
Dialog MouseListener mouseReleased(MouseEvent e)
frame MouseListener mouseEntered(MouseEvent e)
Panel MouseListener mouseExisted(MouseEvent e)
Window MouseListener mouseClicked(MouseEvent e)
Component KeyListener keyTyped(KeyEvent e)
Component KeyListener keyPressed(KeyEvent e)
Component KeyListener keyReleased(KeyEvent e)
Component FocusListener focusGained(FocusEvent e)
Component FocusListener focusLost(FocusEvent e)t
TextComponent TextListener textValueChanged(TextEvet e)
Events and Methods
ActionEvent:
1.When button is get clicked
2.When menu item is selected
3.When list item is double clicked
4.When enter key pressed in text field
Method:
-------------->getSource() gives the source that made this event
ItemEvent:
1.When a check box is selected/deselected
2.When choice item is selected/deselected
3.When list item is selected/deselected
4.When check box menu item is selected/deselected
Method:
-------------->getItemSelectable() gives reference to the item selected component
getItem() gives reference to the item that caused the event
AdjustmentEvent:
1.When a scroll bar thumb is moved
Method:
-------------->getAdjustable() gives the object that caused the event
getValue() gives the new value
TextEvent:
1.When content of text is changed in TextField,TextArea
MouseEvent:
1.When user clicks or moves the mouse pointer
Method:
------------->getX(),getY() gives x,y screen coordinates of mouse position
getClickCount() gives click count for an event
WindowEvent:
1.When a window minimized ,opened ,activated etc.
FocusEvent:
1.When a component gains or loses focus
KeyEvent:
1.Its is generated by the user during interaction from keyboard
Method:
1.getKeyCode() gives the key code for a given char
2.getkeyChar() gives char defined by a key code.
Category: Java, Programming
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