private static final int ButtonWidth = 256, ButtonHeight = 256;

  public MenuState(Handler handler){
    super(handler);
  }

  @Override
  public void tick() {
    if(handler.getMouseManager().isLeftPressed())
      State.setState(handler.getGame().gameState);
  }

  @Override
  public void render(Graphics g) {
    g.setColor(Color.RED);
    g.fillRect(handler.getMouseManager().getMouseX(), handler.getMouseManager().getMouseY(), 8, 8);
    g.drawImage(Assets.PlayButton, 500, 100, ButtonWidth, ButtonHeight, null );
    g.drawImage(Assets.ExitButton, 500, 400, ButtonWidth, ButtonHeight, null);
  }
}

private boolean leftPressed;
  private int mouseX, mouseY;

  public MouseManager(){

  }

  //Getters

  public boolean isLeftPressed(){
    return leftPressed;
  }

  public int getMouseX(){
    return mouseX;
  }

  public int getMouseY(){
    return mouseY;
  }

  // Implemented methods

  @Override
  public void mousePressed(MouseEvent e) {
    if(e.getButton() == MouseEvent.BUTTON1)
      leftPressed = true;

  }

  @Override
  public void mouseReleased(MouseEvent e) {
    if(e.getButton() == MouseEvent.BUTTON1)
      leftPressed = false;
  }

  @Override
  public void mouseMoved(MouseEvent e) {
    mouseX = e.getX();
    mouseY = e.getY();
  }

  @Override
  public void mouseDragged(MouseEvent e) {
    // TODO Auto-generated method stub

  }

  @Override
  public void mouseClicked(MouseEvent e) {
    // TODO Auto-generated method stub

  }

  @Override
  public void mouseEntered(MouseEvent e) {
    // TODO Auto-generated method stub

  }

  @Override
  public void mouseExited(MouseEvent e) {
    // TODO Auto-generated method stub

  }
}

public class Handler {

  private Game game;
  private World world;

  public Handler(Game game){
    this.game = game;
  }

  public GameCamera getGameCamera(){
    return game.getGameCamera();
  }

  public KeyManager getKeyManager(){
    return game.getKeyManager();
  }

  public MouseManager getMouseManager(){
    return game.getMouseManager();
  }

  public int getWidth(){
    return game.getWidth();
  }

  public int getHeight(){
    return game.getHeight();
  }

  public Game getGame() {
    return game;
  }

  public void setGame(Game game) {
    this.game = game;
  }

  public World getWorld() {
    return world;
  }

  public void setWorld(World world) {
    this.world = world;
  }
}

private Display display;
  private int width, height;
  public String title;

  private boolean running = false;
  private Thread thread;

  private BufferStrategy bs;
  private Graphics g;

  //States
  public State gameState;
  public MenuState menuState;

  //Input
  private KeyManager keyManager;
  private MouseManager mouseManager;

  //Camera
  private GameCamera gameCamera;

  //Handler
  private Handler handler;

  public Game(String title, int width, int height){
    this.width = width;
    this.height = height;
    this.title = title;
    keyManager = new KeyManager();
    mouseManager = new MouseManager();
  }

  private void init(){
    display = new Display(title, width, height);
    display.getFrame().addKeyListener(keyManager);
    display.getFrame().addMouseListener(mouseManager);
    display.getFrame().addMouseMotionListener(mouseManager);
    display.getCanvas().addMouseListener(mouseManager);
    display.getCanvas().addMouseMotionListener(mouseManager);
    Assets.init();

    handler = new Handler(this);
    gameCamera = new GameCamera(handler, 0, 0);

    gameState = new GameState(handler);
    menuState = new MenuState(handler);
    State.setState(menuState);
  }

  private void tick(){
    keyManager.tick();

    if(State.getState() != null);
        State.getState().tick();
  }

  private void render(){
    bs = display.getCanvas().getBufferStrategy();
    if(bs == null){
      display.getCanvas().createBufferStrategy(3);
      return;
    }
    g = bs.getDrawGraphics();
    //Clear Screen
    g.clearRect(0, 0, width, height);
    //Draw Here!

    if(State.getState() != null);
          State.getState().render(g);

    //End Drawing!
    bs.show();
    g.dispose();
  }

  public void run(){

    init();

    int fps = 1000;
    double timePerTick = 1000000000 / fps;
    double delta = 0;
    long now;
    long lastTime = System.nanoTime();
    long timer = 0;
    int ticks = 0;

    while(running){
      now = System.nanoTime();
      delta += (now - lastTime) / timePerTick;
      timer += now - lastTime;
      lastTime = now;

      if(delta >=1){
        tick();
          render();
          ticks++;
          delta--;
      }
      if(timer >= 1000000000){
        System.out.println("Tick and Frames:" + ticks);
        ticks = 0;
        timer = 0;
      }
    }

    stop();

  }

  public KeyManager getKeyManager(){
    return keyManager;
  }

  public MouseManager getMouseManager(){
    return mouseManager;
  }

  public GameCamera getGameCamera(){
    return gameCamera;
  }

  public int getWidth(){
    return width;
  }

  public int getHeight(){
    return height;
  }

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

  public synchronized void stop(){
    if(!running)
      return;
    running = false;
    try {
      thread.join();
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
}

public void mouseClicked(MouseEvent e){
   if(button.x < e.getX() && buttonWidth + button.x > e.getX() && button.y < e.getY() && button.y + buttonHeight > e.getY(){
        //Button has been clicked
    }
}

import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

public class Game implements MouseListener{

    public static void main(String[] args){
            new Game();
    }

    private JFrame frame;
    private Game(){
        init();
        loop();
    }

    private void init(){
        frame = new JFrame("TEST");
        frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
        frame.setSize(600, 400);
        frame.addMouseListener(this);
        running = true;
        frame.setVisible(true);
    }

    private boolean shouldClose = false;
    private boolean running;
    private final int buttonWidth = 100;
    private final int buttonHeight = 50;
    private void loop(){
        while(running){
            Graphics g = frame.getGraphics();
            g.drawRect(500, 100, buttonWidth, buttonHeight);
        }
        frame.setVisible(false);
    }

@Override
public void mouseClicked(MouseEvent e) {
    if(500 < e.getX() && buttonWidth + 500 > e.getX() && 100 < e.getY() && 100 + buttonHeight > e.getY()){
        System.out.println("BUTTON WAS PRESSED!");
        running = false;
    }
}

@Override
public void mousePressed(MouseEvent e) {

}

@Override
public void mouseReleased(MouseEvent e) {

}

@Override
public void mouseEntered(MouseEvent e) {

}

@Override
public void mouseExited(MouseEvent e) {

}
}