Class Abacus

Class Abacus 

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Container
                   |
                   +----java.awt.Panel
                           |
                           +----java.applet.Applet
                                   |
                                   +----Abacus
public class Abacus
extends Applet
This is a java-applet simulation of a Chinese abacus. Each column is stored internally in an integer array called 'column' that is initialized to represent the resting positions of the beads: 2 bead on top deck row-pos 0 & 1, pos 2 empty; 5 beads lower deck pos 4-8, pos 3 empty. The initial value is 499d=111110011 where a '1' represents a position that is occupied by a bead and a '0' represents an empty position. As the beads are moved, the 1's are shifted (using << and >>) accordingly to represent their new locations. The illustration below represents a single column of the abacus. 
 
   O represents the bead; 
   | represents an empty position (the rod)
   = represents the frame
  	=============	Row Position (index 'r' )
  		O			0
  		O			1			Upper Deck
  		|			2
  	=============
  		|			3
  		O			4
  		O			5			Lower Deck
  		O			6
  		O			7
  		O			8
	=============

Constructor Index

o Abacus()

Method Index

o animateBead(int, int)
Moves the bead specified by r & c in the appropriate direction
o getAppletInfo()
Tourist information.
o getParameterInfo()
Parameters user can customize.(Applet->Info)
o init()
Initialize the Abacus by initializing the internal column array.
o mouseMove(Event, int, int)
Track the mouse.
o mouseUp(Event, int, int)
Handle a mouse-click.
o paint(Graphics)
Draw the abacus :draw the frame, draw the rods & draw the beads; display the value in the frame.
o update(Graphics)

Constructors

o Abacus 
  public Abacus()

Methods

o getAppletInfo 
  public String getAppletInfo()
Tourist information. (Applet->Info)
Overrides:
getAppletInfo in class Applet
o getParameterInfo 
  public String[][] getParameterInfo()
Parameters user can customize.(Applet->Info)
Overrides:
getParameterInfo in class Applet
o init 
  public void init()
Initialize the Abacus by initializing the internal column array. If a "VALUE" resource is specified, set the column array according to it, instead.
Overrides:
init in class Applet
o paint 
  public void paint(Graphics g)
Draw the abacus :draw the frame, draw the rods & draw the beads; display the value in the frame.
Overrides:
paint in class Component
o update 
  public void update(Graphics g)
Overrides:
update in class Component
o mouseUp 
  public boolean mouseUp(Event evt,
                         int x,
                         int y)
Handle a mouse-click. Convert the x/y position of the click to a row/column equivalent and move the corresponding bead.
Parameters:
evt - the internal AWT event varaible
x - the x-position of the click, in pixels
y - the y-position of the click, in pixels
Overrides:
mouseUp in class Component
o mouseMove 
  public boolean mouseMove(Event evt,
                           int x,
                           int y)
Track the mouse. Display help information in the status area as the mouse moves over various hot-points.
Parameters:
evt - the internal AWT event varaible
x - the x-position of the mouse, in pixels
y - the y-position of the mouse, in pixels
Overrides:
mouseMove in class Component
o animateBead 
  public void animateBead(int r,
                          int c)
Moves the bead specified by r & c in the appropriate direction
Parameters:
r - is the row number for the bead
c - is the column number for the bead