Game.java

package com.tutorial.main;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferStrategy;
import java.util.Random;

public class Game extends Canvas implements Runnable{
	
	public static Handler handler = new Handler();
	private static final long serialVersionUID = 1550691097823471818L;
	public static final int WIDTH = 640, HEIGHT = WIDTH / 12 * 9;
	private Thread thread;
	private boolean running = false;
	public static HUD hud = new HUD();
	private Spawn spawner;
	public static Menu menu;
	private Help help;
	public STATE gameState = STATE.Menu;
	
	public Game() {

		menu = new Menu(this);
		help = new Help(this);
		this.addKeyListener(new KeyInput(this));
		this.addMouseListener(menu);
		this.addMouseListener(help);
	
		new Window(WIDTH, HEIGHT, "Let's Build a Game!", this);

		spawner = new Spawn();
	}

	
	public enum STATE {
		Menu,
		Help,
		Game
	};
	


	public synchronized void start(){
		thread = new Thread(this);
		thread.start();
		running = true;
	}

	public synchronized void stop(){
		try{
			thread.join();
			running = false;
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	
	public void run(){
		this.requestFocus();
		long lastTime = System.nanoTime();
		double amountOfTicks = 60.0;
		double ns = 1000000000 / amountOfTicks;
		double delta = 0;
		long timer = System.currentTimeMillis();
		int frames = 0;
		while(running){
			long now = System.nanoTime();
			delta += (now - lastTime) / ns;
			lastTime = now;
			while(delta >= 1){
				tick();
				delta--;
			}
			if(running)
				render();
			frames++;
			
			if(System.currentTimeMillis() - timer > 1000){
				timer += 1000;
				//System.out.println("FPS: " + frames);
				frames = 0;
			}
			
		}
		stop();
	}
		
		
		private void tick(){
			handler.tick();
			if(gameState == STATE.Game){
				hud.tick();
				spawner.tick();				
			}else if(gameState == STATE.Menu){
				menu.tick();
			}else if(gameState == STATE.Help){
				help.tick();
			}
		}
		
		private void render() {
			BufferStrategy bs = this.getBufferStrategy();
			
			if(bs == null){
				this.createBufferStrategy(3);
				return;
			}
			
			Graphics g = bs.getDrawGraphics();
			
			g.setColor(Color.black);
			g.fillRect(0,0,WIDTH,HEIGHT);
			
			handler.render(g);
			
			if(gameState == STATE.Game){
				hud.render(g);			
			}
			else if(gameState == STATE.Menu){				
				menu.render(g);
			}else if(gameState == STATE.Help){				
				help.render(g);
			}

			
			g.dispose();
			bs.show();
		} // end render
		
	public static int clamp(int var, int min, int max){
		if (var >= max)
			return var = max;
		else if (var <= min)
			return var = min;
		else
			return var;
	}
	
	public static void main(String[] args){
		new Game();
	}
}

Handler.java

package com.tutorial.main;

import java.awt.Graphics;
import java.util.LinkedList;

public class Handler {

	LinkedList<GameObject> objectList = new LinkedList<GameObject>();
	
	public void tick(){
		for(int i = 0; i < objectList.size(); i++){
			GameObject tempObject = objectList.get(i);
			tempObject.tick();
		}
		
	}
	public void render(Graphics g){
		for(int i = 0; i < objectList.size(); i++){
			if(objectList.size() != 0){
				GameObject tempObject = objectList.get(i);
				tempObject.render(g);
			}
		}
	}
	
	public void addObject(GameObject object){
		objectList.add(object);
	}
	public void removeObject(GameObject object){
		objectList.remove(object);
	}
	public void clearEnemies(){
		for(int i = 0; i < objectList.size(); i++){
			GameObject tempObject = objectList.get(i);
			if(tempObject.getId() == ID.Player){
			objectList.clear();
			addObject(new Player(tempObject.getX(),tempObject.getY(), ID.Player));				
			}
		}
	}
}