Combat system

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

/**
 * A Counter class that allows you to display a numerical value on screen.
 * 
 * The Counter is an actor, so you will need to create it, and then add it to
 * the world in Greenfoot.  If you keep a reference to the Counter then you
 * can adjust its value.  Here's an example of a world class that
 * displays a counter with the number of act cycles that have occurred:
 * 
 * <pre>
 * class CountingWorld
 * {
 *     private Counter actCounter;
 *     
 *     public CountingWorld()
 *     {
 *         super(600, 400, 1);
 *         actCounter = new Counter("Act Cycles: ");
 *         addObject(actCounter, 100, 100);
 *     }
 *     
 *     public void act()
 *     {
 *         actCounter.setValue(actCounter.getValue() + 1);
 *     }
 * }
 * </pre>
 * 
 * @author Neil Brown and Michael Kölling 
 * @version 1.0
 */
public class Counter extends Actor
{
    private static final Color transparent = new Color(0,0,0,0);
    private GreenfootImage background;
    private int value;
    private int target;
    private String prefix;
    
    public Counter()
    {
        this(new String());
    }

    /**
     * Create a new counter, initialised to 0.
     */
    public Counter(String prefix)
    {
        background = getImage();  // get image from class
        value = 0;
        target = 0;
        this.prefix = prefix;
        updateImage();
    }
    
    /**
     * Animate the display to count up (or down) to the current target value.
     */
    public void act() 
    {
        if (value < target) {
            value++;
            updateImage();
        }
        else if (value > target) {
            value--;
            updateImage();
        }
        
        if (value <= 5)
        {
           setImage("LevelOneRose"+ value +".png");
        }
        else if (value >= 6 && value <= 10)
        {
            setImage("LevelTwoRose"+ value +".png");
        }
        else if (value >= 11 && value <= 15)
        {
            setImage("LevelThreeRose"+ value +".png");
        }
        else if (value >= 16 && value <= 20)
        {
            setImage("LevelFourRose"+ value +".png");
        }
        else if (value >= 21 && value <= 25)
        {
            setImage("LevelFiveRose"+ value +".png");
        }
        else if (value >= 26 && value <= 30)
        {
            setImage("LevelSixRose"+ value +".png");
        }
        else if (value >= 31 && value <= 35)
        {
            setImage("LevelSevenRose"+ value +".png");
        }
        else if (value >= 36 && value <= 40)
        {
            setImage("LevelEightRose"+ value +".png");
        }
        else if (value >= 41 && value <= 45)
        {
            setImage("LevelNineRose"+ value +".png");
        }
        else if (value >= 56 && value <= 50)
        {
            setImage("LevelTenRose"+ value +".png");
        }
        else if (value >= 50)
        {
            setImage("LevelTenRose50.png");
        }
    }

    /**
     * Add a new score to the current counter value.  This will animate
     * the counter over consecutive frames until it reaches the new value.
     */
    public void add(int score)
    {
        target += score;
    }

    /**
     * Return the current counter value.
     */
    public int getValue()
    {
        return target;
    }

    /**
     * Set a new counter value.  This will not animate the counter.
     */
    public void setValue(int newValue)
    {
        target = newValue;
        value = newValue;
        updateImage();
    }
    
    /**
     * Sets a text prefix that should be displayed before
     * the counter value (e.g. "Score: ").
     */
    public void setPrefix(String prefix)
    {
        this.prefix = prefix;
        updateImage();
    }

    /**
     * Update the image on screen to show the current value.
     */
    private void updateImage()
    {
        GreenfootImage image = new GreenfootImage(background);
        GreenfootImage text = new GreenfootImage(prefix + value , 22, Color.BLACK, transparent);
        
        if (text.getWidth() > image.getWidth() - 20)
        {
            image.scale(text.getWidth() + 20, image.getHeight());
        }
        
        image.drawImage(text, (image.getWidth()-text.getWidth())/2, 
                        (image.getHeight()-text.getHeight())/2);
        setImage(image);
    }
}

import greenfoot.*;

/**
 *
 */
public class LevelOne extends SWorld
{
    private int timer = 0;
    Counter counter = new Counter("");
    private int levelUp;
    /**
     * Creates a scrolling world using a main actor, a background, some obstacles, and a non-scrolling score.
     */
    public LevelOne()
    {    
        super(1000, 600, 1, 2000); // scroll world constructor call; last parameter is scroll width
        // in the following statement, the main actor is placed in the center of the window
        setMainActor(new Girl(), 250, 300); // the int parameters are centered window x and y ranges
        // to start the main actor elsewhere
        mainActor.setLocation(100, 342);
        GreenfootImage bg = new GreenfootImage("Background1.jpeg");
        setScrollingBackground(bg); // set the scolling background image
        // add other scrollable objects normally
        //''addObject(new Ground(), 248, 607);''
        // use of the following also adds scrollable objects
        //''addObject(new Box(), 380, 345, true);'' // the boolean determines scrollable state
        // use the following for non-scrollable objects
        //''addObject(new Score(), 40, 390, false);''
        addObject(counter, 66, 106, false);
    }

    public void act()
    {
        if (getObjects(Enemy.class).isEmpty())
        {
            timer++;
            if(timer == 1)
            {
               // killCount();
            }

            if (timer >= 100)
            {                
                //addObject(counter2, 400, 350);
                addObject(new Enemy(), 400, 400);
                timer = 0;
            }
        }
        if (levelUp++ == 20)
            {
                killCount();
                levelUp = 0;
            }
    }

    public void killCount()
    {
        counter.add(1);
    }

}