GameManager.java

import greenfoot.*; // import every greefoot function, object and more
import java.util.*; // import java utils
import java.text.*; // import java text utils

public class GameManager extends Manager  
{
    private static boolean isGameStarted = false; // use to check internal if the game has started
    private static boolean isGameOver = false; // use to check internal if the game is over (=> player died)
    private static GreenfootSound gameMusic = new GreenfootSound("./music/gameMusic.mp3"); // the background music
    private static ArrayList<String> lastPlayedTimes = new ArrayList<>(); // a list of the last 5 game times in ms
    private static long gameStartedAt; // time in ms when game started
    
    public static void start() {
        NinjaEnemyManager.insert(); // add all ninajs to the ninaj enemy array
        
        isGameOver = false;
        isGameStarted = true;
        gameStartedAt = System.currentTimeMillis();
        
        MapManager.insertMap();
        gameMusic.playLoop();
    }
    
    public static void stop() {
        isGameStarted = false;
        isGameOver = true;
        
        // ensures that only 3 entries are in the array
        if (lastPlayedTimes.size() == 3) {
            lastPlayedTimes.remove(3);
        }
        lastPlayedTimes.add(getConvertedPlayTime());
        
        NinjaEnemyManager.clear(); // clear the ninja enemy array
        
        MapManager.insertMap();
        gameMusic.stop();
    }
    
    public static ArrayList<String> getLastPlayedTimes() {
        return lastPlayedTimes;
    }
    
    public static boolean isGameStarted() {
        return isGameStarted;
    }
    
    public static boolean isGameOver() {
        return isGameOver;
    }
    
    public static long getStartedAt() {
        return gameStartedAt;
    }
    
    public static long getCurrentPlayTime() {
        return System.currentTimeMillis();
    }
    
    public static String getConvertedPlayTime() 
    {
        // calculates the elapsed game time in milliseconds by comparing the current time with the time the game started at
        int gameDuration = (int) (System.currentTimeMillis() - gameStartedAt);
        
        int hours = gameDuration / 3600000; // calculate the hours from the game time (1 hour = 3600000 milliseconds)
        gameDuration -= hours * 3600000; // remove the milliseconds that have already been taken into account for the hours
        
        int minutes = gameDuration / 60000; // calculate the minutes from the game time (1 minute = 60000 milliseconds)
        gameDuration -= minutes * 60000; // remove the milliseconds that have already been taken into account for the minutes
        
        int seconds = gameDuration / 1000; // calculate the seconds from the game time (1 second = 1000 milliseconds)
        
        // format the game time
        return new DecimalFormat("00").format(hours) 
        + ":" 
        + new DecimalFormat("00").format(minutes) 
        + ":" 
        + new DecimalFormat("00").format(seconds) 
        + "h";
    }
}