Bullets

import greenfoot.*;  // (World, Actor, GreenfootImage, and Greenfoot)
import java.util.List;


import java.awt.Color;
import java.awt.Font;

/**
 * A bullet that can hit boid or Predator.
 * 
 * @author Poul Henriksen
 */ 
public class Bullet extends SmoothMover
{
      
    /**  
     * A bullet looses one life each act, and will disappear when life = 0
     * Increase the life to make the bullet fly further
    */
    private int life = 5;
    
    public Bullet()
    {
        
    }
    
    public Bullet (Vector speed, int rotation)
    {
        super(speed);
        setRotation(rotation);
        addForce(new Vector(rotation, 15));
        
    }
    
    /**
     * The bullet will kill the boids if it hits them.
     */
    public void act()
    {
        
        /**
         * Check to see if the bullet is at the word's edge, if so remove it
         */
        if(isAtEdge())
        {
            getWorld().removeObject(this);
        }
        /**
         * If the bullet isn't at the world's edge then continue
         */
        else
        {
            /**
             * If the bullet has flown far enough remove it from the world
             */
            if(life <= 0) 
            {
                getWorld().removeObject(this);
            }
            /**
             * If not decrement the life by one, move it and then check and see if it hit anything
             */
            else
            {
                life--;
                move();
                /**
                 * Inside of the if statement we will check and see if we hit a boid
                 * If we do the method will return a true, which means that the bullet
                 * doesn't exist any more and we don't want to check to see if we hit a predator
                 * So, only run the if statement if we don't hit a boid.
                 */
                if(!checkBoidHit())
                {
                    checkPredatorHit();
                }
            }
        }
        
    }
    
    /**
     * Check whether we have hit a boid.
     */
    private boolean checkBoidHit()
    {
        /**
         * To ensure that our bullet actually "hits" the boid we have to check a range around it
         * This is due to the small size of both objects and the speed at which they are moving.
         */
        int range = 10;
        boolean hit = false;
        List<Boid> boids = getObjectsInRange(range,Boid.class);
        /**
         * If the bullet hits a boid, then remove the boid
         */
        for (Boid boid : boids)
        {
            boid.hit();
            hit = true;   
        }

        /**
         * If the bullet hit a boid then remove the bullet from the world
        */ 
        if(hit)
        {
            getWorld().removeObject(this);
        }
        
        return hit;
    }
    
    /**
     * Check whether we have hit a predator.
     */
    private void checkPredatorHit()
    {
        Sky sky = (Sky)getWorld();
        /**
         * Check and see if we have anymore predators in the world
         */
        if(sky.getNumberOfPredators() > 0)
        {
            Predator predator = (Predator)getOneIntersectingObject(Predator.class);
            /**
               * If the bullet hit a predator then remove it from the world
               * Note: if the bullet doesn't hit anything then the predator object
               * will be null, meaning nothing
             */ 
            if(predator != null)
            {
                //predator.hit();
                getWorld().removeObject(this);
            }
        }
    }
}

private void fire()
{
    Bullet bullet = new Bullet(15, getRotation()); 
    getWorld().addObject(bullet, getX(), getY());
    bullet.move();
}