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Concurrent Programming with Java
Lab Manual, Version 1.0, F. Astha Ekadiyanto, 2002.

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Lab 1: Introduction to Lab. Environment and Object Orientation

Object First
- Cell Class
  - CircleCell Class
  - SquareCell Class
  - HexCell Class
- RBS Class (Radio Base Station)
- MSC Class (Mobile Switching Center)

HexCell Class

The Hex Cell Class is a subclass of Cell Class. It is a specialized cell which only handles hexagonal shape cells. Thus, there should be some overrides in the class definition to make it more specialized.

The special classification of a Hex Cell Class is as follows:

Calculate its area using Hexagonal equation which is
Override the coverage behavior since the super class definition is not valid for hex cells.
The overide can be performed by transforming the relative location of x,y point into the first quardrat of the Hexagonal area and then check whether it exceeds the boundaries.

These definitions can be implemented in Java Language as follows :

File name: HexCell.java

Class Fields :

CELLTYPE : Indicates the type of shape it handles.
RATIO : A constant used in area calculation.

Class Constructors:

HexCell(x,y,r) : Initializes all Class Fields using passing arguments

Class Methods:

area( ) : returns the area of the Cell (implements which was once abstract in superclass).
coverage(x,y) : returns true when x,y is covered in the Cell (overrides superclass behavior)
- yLimit(x) : returns the first quardrant of y-boundary by given relative x (only used in coverage(x,y) method - it is private).

import java.lang.Math; 
// Required by Math.sqrt() static method call in the class definition
/**
 * A Circle Cell 
 * 
 * @author: CPwJ
 * @version: 1.0 (2002)
 */
public abstract class HexCell extends Cell
{
	// instance variables 
	//Information about a cell (x,y coordinate and r cell radius)
  private static final double RATIO = 2.5980762;  //ratio used in area calculation
  private static final String CELLTYPE = "Hexagonal"; //type of cell shape
  /**
   * CircleCell constructor
   * @param x  Cell X coordinate 
   * @param y  Cell Y coordinate 
   * @param r  Cell Radius
   */
   public HexCell(double x, double y, double r) 
   {
       super(x,y,r);
   }
  /**
   * Calculate the area of a Circle shape Cell
   * @return     the area of the Circle Cell
   */
   public double area()
   {
       return RATIO*getR()*getR();
   }
    /**
     * Check whether a point is covered by the Hex cell
     * @param x   The x point of access coordinate
     * @param y   The y point of access coordinate
     * @return  True/False
     */
    public boolean coverage(double x, double y)
    {
        double relativeX = Math.abs(x-getX());
        double relativeY = Math.abs(y-getY());
        if ( relativeY > yLimit(relativeX) ) return false;
        return true;
    }
    /**
     * Calculate the first quardrant of Hex boundary
     * @param x   The x point of access coordinate
     * @return  The Y boundary
     */
    private double yLimit(double x)
    {
            double r = getR();
            double maxY = r * Math.sin(Math.PI / 3);
            double minY = 0.0;
            if ( x < r/2 ) return maxY;
            if ( x > r ) return minY;
            return (2 * maxY * (1 - x / r) );
    }
}

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