Flyweight

import java.util.*;

enum BulletType { //type of bullets available
    FIVE_MM,
    SEVEN_MM,
    NINE_MM,
}
//-------------
class Bullet{ //intrinsic properties
    int weight;
    int radius;
    BulletType bulletType;
    
    Bullet(BulletType bulletType, int radius, int weight){
        this.bulletType = bulletType;
        this.radius = radius;
        this.weight = weight;
    }
}
//-------------
class FlyingBullet{ //exterinsic properties
    int speed;
    String direction;
    Bullet bullet;
    FlyingBullet(Bullet bullet, String direction, int speed){
        this.bullet = bullet;
        this.direction = direction;
        this.speed = speed;
    }
}
//--------------
class BulletRegistry { //register few types of bullets
    private Map<BulletType, Bullet> bullets = new HashMap<>();

    public void registerBullet(BulletType type, Bullet bullet) { //register bullet
        bullets.put(type, bullet);
    }

    public Bullet getBullet(BulletType bulletType) { //return bullet based on type
        return bullets.get(bulletType);
    }
}

//---------------

public class Game{
    public static void main(String[] args){
        BulletRegistry bulletRegistory = new BulletRegistry();
        //create bullets
        Bullet fivemm = new Bullet(BulletType.FIVE_MM, 5,50);
        Bullet sevenmm = new Bullet(BulletType.SEVEN_MM, 7,70);
        Bullet ninemm = new Bullet(BulletType.NINE_MM, 9,90);
        //add them in registry
        bulletRegistory.registerBullet(BulletType.FIVE_MM, fivemm);
        bulletRegistory.registerBullet(BulletType.FIVE_MM, fivemm);
        bulletRegistory.registerBullet(BulletType.FIVE_MM, fivemm);
        //create list of Flying Bullets
        
        List<FlyingBullet> flyingBullets = new ArrayList<>();
        
        //make 2000 five mm bullets
        for(int i=0;i<2000;i++){
            FlyingBullet fb = new FlyingBullet(bulletRegistory.getBullet(BulletType.FIVE_MM),"North",100);
            flyingBullets.add(fb);
        }
        //make 100 nine mm bullets
        for(int i=0;i<100;i++){
            FlyingBullet fb = new FlyingBullet(bulletRegistory.getBullet(BulletType.NINE_MM),"South",100);
            flyingBullets.add(fb);
        }
    }
}