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Class programming101.calculBeanz.CalculatorButton

java.lang.Object
    |
    +----java.awt.Component
            |
            +----java.awt.Button
                    |
                    +----programming101.calculBeanz.CalculatorButton

public abstract class CalculatorButton
extends Button
implements ActionListener, Control

Basic calculator button class. This is the C-component in the Model-View-Control (MVC) design pattern. This class

extends java.awt.Button
in order to be a visible bean
implements java.awt.event.ActionListener
guarantees code for the actionPerformed method which is invoked by button events
implments FR.essi.sander.graphix.mvc.Control
guarantees code implementing management for ControlListeners

This class is abstract and cannot be instantiated. It must be subclassed to implement the following abstract method(s):

op - the method specific to each button

Since:: 18/03/98
Version:: 1.3 (6/04/98)
Author:: © 1998 Peter T. Sander
See Also:: FR.essi.sander.graphix.mvc.ControlImpl

CalculatorButton(): No-args constructor (needed for JavaBeans).

actionPerformed(ActionEvent): Method guaranteed by implementing the ActionListener interface.
addControlListener(ControlListener): Registers another listener to be informed when a button is clicked.
fireControlEvent(ControlEvent): Fires a button event to registered listeners.
getPreferredSize(): Getter method for button size attributes.
op(double, double, CalculatorButton): The method specific to each button.
removeControlListener(ControlListener): Removes a listener.
setSize(int, int): Setter method for button size attributes.

CalculatorButton

public CalculatorButton()

No-args constructor (needed for JavaBeans). Registers itself as a listener for button events.

addControlListener

public void addControlListener(ControlListener listener)

Registers another listener to be informed when a button is clicked. The actual management is delegated to the ControlImpl object.

Parameters:: listener - listener to add

removeControlListener

public void removeControlListener(ControlListener listener)

Removes a listener. The actual management is delegated to the ControlImpl object.

Parameters:: listener - listener to remove

fireControlEvent

public void fireControlEvent(ControlEvent ce)

Fires a button event to registered listeners. The actual management is delegated to the ControlImpl object.

Parameters:: be - button event encapsulating relevant button information

setSize

public void setSize(int width,
                    int height)

Setter method for button size attributes.

Parameters:: width - width of button; height - height of buttn
Overrides:: setSize in class Component

getPreferredSize

public Dimension getPreferredSize()

Getter method for button size attributes.

Returns:: dimensions of the button
Overrides:: getPreferredSize in class Component

public abstract double op(double cumul,
                          double entry,
                          CalculatorButton lastButton)

The method specific to each button.

Parameters:: cumul - the current cumulator value; entry - the newly-entered value; lastButton - the button clicked before this one
Returns:: new cumulator value

actionPerformed

public void actionPerformed(ActionEvent ae)

Method guaranteed by implementing the ActionListener interface. Invoked by the underlying windowing system to handle button click events.

Parameters:: ae - action event fired by the windowing system

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