Cell c = new GameOfLifeCell(myCellSize); // Create a cell of a certain size
                myCells[i][j] = c;                       // Add a reference to this cell in the myCells array. Used above in the act method.
                setInitCellState(c);                   // Set whether the cell is white or black
                addObject(c, i, j);                     // Add the cell to the world

    public void setState(boolean state) {
        myState = state;
        showState();
    }

    private void showState() {
        if (myState) 
            myBody.setColor(Color.black);
        else 
            myBody.setColor(Color.white);
        myBody.fillRect(1, 1, myBodySize, myBodySize);
    }

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.awt.Color;
import java.util.List;

/**
 * These are the cells of the CA. They save their last states to allow
 * for parallel reevaluation of neighboring cells.
 * 
 * @David Brown 
 * @03/16/2010
 */
public class Cell  extends Actor
{
    Boolean         myFirstTime = true;
    Boolean         myState, myLastState;
    GreenfootImage  myBody;
    int             myNumNeighbors;
    int             myBodySize;
    Cell []         myNeighbors;
    
    /**
     * Create the cell body's image and initialize state.
     */
    public Cell(int cellSize) {
        super();
        myState = myLastState = false;
        myBody = new GreenfootImage(cellSize, cellSize);
        setImage(myBody);
        myBodySize = cellSize - 2;
        showState();
    }
    
    /**
     * On first execution, find and save neighboring cell references.
     * After that, apply cell rule and show cell state.
     */
    public void act() 
    {
        if (myFirstTime) {
            List neighbors = getNeighbours(1, true, Cell.class);
            myNumNeighbors = neighbors.size();
            myNeighbors = new Cell[myNumNeighbors];
            for(int i = 0; i < myNumNeighbors; i++)
                myNeighbors[i] = (Cell)neighbors.get(i);
            myFirstTime = false;
         }
         applyRule();
         showState();
    }
    
    /**
     * Save the previous state in preparation for the next time step.
     */
    public void saveLastState() {
        myLastState = myState;
    }
    
    /**
     * Set the state of the cell.
     */
    public void setState(boolean state) {
        myState = state;
        showState();
    }
    
    /**
     * Get the state of the cell.
     */
    public boolean getState() {
       return(myState);
    }

    /**
     * Flip the state of the cell.
     */
    public void flipState() {
        setState(!myState);
    }
    
    /**
     * Count the surrounding cells that were on in the previous time step.
     */
    public int countNeighbors() {
        int sum = 0;
        for(int i = 0; i < myNumNeighbors; i++) 
            if (myNeighbors[i].myLastState)
                sum++;
        return(sum);
    }
    
    /**
     * Apply cell rule for timestep. Subclasses should override this method
     * which does nothing.
     */
    public void applyRule() {
    }
    
    /**
     * Draw the body of the cell based on the state.
     */
    private void showState() {
        if (myState) 
            myBody.setColor(Color.black);
        else 
            myBody.setColor(Color.white);
        myBody.fillRect(1, 1, myBodySize, myBodySize);
    }
}

private void createCells() {  
        myCells = new Cell[myHeight][myWidth];  
        for (int i = 0; i < myHeight; i++)  
            for (int j = 0; j < myWidth; j++) {  
                Cell c = new GameOfLifeCell(myCellSize);  
                myCells[i][j] = c;  
                setInitCellState(c); // do we want this cell, that we just placed down, to be true (alive) or false (dead). By default, they are dead
                addObject(c, i, j);  
            }  
    }  	

public void setInitCellState(Cell c) {  
       if (Greenfoot.getRandomNumber(4) == 0) // get a random number between 0 and 3. If the random number is 0, set that cell to true (alive)
           c.setState(true);  				  
    }  
}