public WombatWorld() 
    {
        super(10, 10, 60);        
        setBackground("cell.jpg");
        setPaintOrder(Wombat.class, Leaf.class);  // draw wombat on top of leaf
        populate();
        randomLeaves(20);
        randomPlums(2);
    }

    /**
     * Populate the world with a fixed scenario of wombats and leaves.
     */    
    public void populate()
    {
        addObject(new Wombat(), 7, 1);
        addObject(new Wombat(), 6, 6);
        addObject(new Wombat(), 1, 7);
        
    }
    
    /**
     * Place a number of leaves into the world at random places.
     * The number of leaves can be specified.
     */
    public void randomLeaves(int howMany)
    {
        for (int i=0; i<howMany; i++) {
            Leaf leaf = new Leaf();
            int x = Greenfoot.getRandomNumber(getWidth());
            int y = Greenfoot.getRandomNumber(getHeight());
            addObject(leaf, x, y);
        }
    }

public class Plum extends Actor
{
    /**
     * Act - do whatever the Plum wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void Plum() 
    {
        int percentage = 10;
        GreenfootImage image = getImage();
        image.scale(image.getWidth()*percentage/100, image.getHeight()*percentage/100);
    }    
}

public Plum()
    {
        GreenfootImage myImage = getImage();
        int myNewHeight = (int)myImage.getHeight()/2;
        int myNewWidth = (int)myImage.getWidth()/2;
        myImage.scale(myNewWidth, myNewHeight);
    }

/** in Plum class */
// static content
private static GreenfootImage image = new GreenfootImage("plum.png"); // adjust filename to match the file in your 'images' folder
static {
    image.scale(image.getWidth()/10, image.getHeight()/10);
}

// the constructor
public Plum() {
    setImage(image);
}