public class Piano extends World
{
    private String[] whiteKeys =
        { "a", "s", "d", "f", "g", "h", "j", "k", "l", ";", "'", "\\" };
    private String[] whiteNotes =
        { "3c", "3d", "3e", "3f", "3g", "3a", "3b", "4c", "4d", "4e", "4f", "4g" };
    private String [] blackKeys =
        { "w", "e", "", "t", "y", "u", "", "o", "p", "", "]" } ;
    private String [] blackNotes = 
        { "3c#", "3d#", "", "3f#", "3g#", "3a#", "", "4c#", "4d#", "", "4f#" }; 
        
    /**
     * Make the piano. This means mostly, apart from defining the size,
     * making the keys and placing them into the world.
     */
    public Piano() 
    {
        super(800, 340, 1);
        makeKeys();
        createMessage();
    }
    
    /**
     * Create the piano keys and place them in the world.
     */
    private void makeKeys() 
    {
        
       
        for(int i = 0; i < whiteKeys.length; i++) {
            Key key = new Key(whiteKeys[i], whiteNotes[i]+".wav", "white-key.png", "white-key-down.png");
            addObject(key, i *key.getImage().getWidth() + key.getImage().getWidth(), key.getImage().getHeight() / 2);
            
        }
        for(int i = 0; i < whiteKeys.length-1; i++) {
            if( ! blackKeys[i].equals("") ) {
                Key key = new Key(blackKeys[i], blackNotes[i]+".wav", "black-key.png", "black-key-down.png");
                addObject(key, i *key.getImage().getWidth() + key.getImage().getWidth() * 2, key.getImage().getHeight() / 2);
            }
        }
    }
   public void createMessage()
   {
       GreenfootImage bg = getBackground();
       bg.drawString("Use keys 'a' to ':' and keys 'q', 'e', 't', 'y', 'u', 'o', 'p', ] to play the piano", 225, 300);
       
    }
}