// get a random number between 0 and 40.
int numNormal = Greenfoot.getRandomNumber(41); 
//40 minus the random number generated above to get the number of Golden
int numGolden = 40-numNormal; 

int numNormal = Greenfoot.getRandomNumber(30)+1; 

/**
 * A world where wombats live.
 * 
 * @author Michael Kolling
 * @version 1.0.1
 */
public class WombatWorld extends World
{
    /**
     * Create a new world with 8x8 cells and
     * with a cell size of 60x60 pixels
     */
    public WombatWorld() 
    {
        super(8, 8, 60);        
        setBackground("cell.jpg");
        setPaintOrder(Wombat.class, Leaf.class, GoldenLeaf.class); //HALL: Wombats walk over Leasves and Golden Leaves
        populateWombatWorld();   
    }

    /**
     * Populate the world with a fixed scenario of wombats and leaves.
     */    
    public void populateWombatWorld()
    {
        placeRandomLeaves(28); //HALL: Place 28 leaves on the world
        placeRandomWombats(5); //HALL: Place 5 wombats on the world (R1)    
        placeRandomGoldenLeaf(12); //HALL: Place 12 Golden Leaves on the World
    }

    /**
     * HALL: this act method keeps track of the number of objects in the world
     */
    public void act()
    {
        if ( countWombatsInTheWorld() <= 0 )  //HALL: if there are no wombats in the world 
        {                                     // stop the simulation (R11)
            Greenfoot.stop();           
        }
    }

    /**
     * HALL: this method counts and return the number of wombats in the world
     */ 

    public int countWombatsInTheWorld()
    {      
        return getObjects(Wombat.class).size();      
    }

    /**
     * HALL: Place a number of leaves into the world at random places.
     * HALL: The number of leaves can be specified.
     */
    public void placeRandomLeaves(int howManyLeaves)
    {
        for(int i = 0; i < howManyLeaves; i++) {                //HALL: (R3)
            Leaf randomLeaf = new Leaf();
            int x = Greenfoot.getRandomNumber(getWidth());
            int y = Greenfoot.getRandomNumber(getHeight());
            addObject(randomLeaf, x, y);
        }
    }

    /**
     * HALL: Place a number of wombats into the world at random places.
     * HALL: The number of wonbats can be specified.
     */
    public void placeRandomWombats(int howManyWombats)
    {
        for(int i = 0; i < howManyWombats; i++) {
            Wombat randomWombat = new Wombat();
            int x = Greenfoot.getRandomNumber(getWidth());
            int y = Greenfoot.getRandomNumber(getHeight());
            addObject(randomWombat, x, y);
        }
    }
    
    /**
     * HALL: Place a number of Golden Leaves into the world at random places.
     * HALL: The number of Golden Leaves can be specified.
     */
    public void placeRandomGoldenLeaf(int howManyGoldenLeaf)
    {
        for(int i = 0; i < howManyGoldenLeaf; i++) {
            GoldenLeaf randomGoldenLeaf = new GoldenLeaf();
            int x = Greenfoot.getRandomNumber(getWidth());
            int y = Greenfoot.getRandomNumber(getHeight());
            addObject(randomGoldenLeaf, x, y);
        }
    }
}

public void populateWombatWorld()  
    {  
        int numNormal = Greenfoot.getRandomNumber(41);
        int numGolden = 40-numNormal;

        placeRandomLeaves(numNormal); //HALL: Place 28 leaves on the world  
        placeRandomWombats(5); //HALL: Place 5 wombats on the world (R1)      
        placeRandomGoldenLeaf(numGolden); //HALL: Place 12 Golden Leaves on the World  
    }