mouse click question

if (Greenfoot.mouseClicked(this))
{
    // get object reference if no readily available
    // assume name as 'morpheus'
    morpheus.updateImage("imageFilename.gif");
}

Morpheus morpheus = new Morpheus();
addObject(morpheus, x_coord, y_coord);
//  assume object to be clicked on as 'Icon.class'
addObject(new Icon(morpheus), x2_coord, y2_coord);

private Morpheus morpheus;

public Icon(Morpheus morph)
{
    morpheus = morph;
    // rest of constructor
}

public void act()
{
    // some of act method (maybe)
    if (Greenfoot.mouseClicked(this)) morpheus.updateImage("imageFilename.gif");
    // rest of act method (maybe)
}

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class LightWorld here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class LightWorld extends World
{
    private Light l1,l2;
    /**
     * Constructor for objects of class LightWorld.
     * 
     */
    public LightWorld()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super(600, 400, 1);
        
        l1 = new Light();
        addObject(l1, 71, 65);
        
        l2 = new Light();
        addObject(l2, 304, 60);
    }
}

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class Button here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Button extends Actor
{
    private GreenfootImage sB0;
    private GreenfootImage sB1;
    private GreenfootImage sBDown;
    private boolean wasBtnPushed;
    
    public Button()
    {
        sB0 = new GreenfootImage ("Button0.png");
        sB1 = new GreenfootImage ("Button1.png");
        sBDown = new GreenfootImage ("ButtonDown.png");
        setImage (sB0);
        wasBtnPushed = false;
        
    }

    /**
     * Act - do whatever the Button wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        if (Greenfoot.mousePressed(this) && !wasBtnPushed)
        {
            setImage (sBDown);
            wasBtnPushed = true;
        }

        if (!Greenfoot.mousePressed(this) && wasBtnPushed)
        {
            setImage (sB1);
            wasBtnPushed = false;
        }
    } 
}

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class Light here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Light extends Actor
{
    private GreenfootImage red;
    private GreenfootImage blue;
    private GreenfootImage off;
    private int count;
    
    
    public Light()
    {
        red = new GreenfootImage("red.png");
        blue = new GreenfootImage("blue.png");
        off = new GreenfootImage("Off.png");
        setImage(off);
        count = 0;
        
        
    }

    /**
     * Act - do whatever the Light wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        if (Greenfoot.mousePressed(this))
        {
            setImage(red);
            count = count +1;
            
        }
        if (Greenfoot.mousePressed(this) && count == 2)
        {
            setImage(blue);
            count = count +1;
            
        }
        if (Greenfoot.mousePressed(this) && count > 3)
        {
            setImage(off);
            count = 0;
            
        }
    }    
}

public void act()
{
    if (count == 0 && Greenfoot.mousePressed(this))
    {
        setImage(red);
        count = count + 1;
    }
    if (count == 1 && Greenfoot.mousePressed(this))
    {
        setImage(blue);
        count = count + 1;
    }
    if (count == 2 && Greenfoot.mousePressed(this))
    {
        setImage(off);
        count = 0;
    }
}

import greenfoot.*;

public class Light extends Actor
{
    private GreenfootImage[] image= {
             new GreenfootImage("Off.png"),
             new GreenfootImage("red.png"),
             new GreenfootImage("blue.png") };
    private state = 0; // same as your 'count'

    public Light()
    {
        setImage(image[state]);
    }

    public void act()
    {
        if (Greenfoot.mouseClicked(this))
        {
            state = (state + 1) % 3;
            setImage(image[state]);
        }
    }
}