class.java使用未經檢查或不安全的操作

Question

我試圖讓我的.jar文件在我的dist文件夾中運行但是它沒有運行，我試圖清理並構建並注意到它正在給出消息：

Note: E:\ZombieDefense\src\GameScreen\ZombieDefense.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

經過一番搜索，我讀到這可能與我在這個類中聲明一些變量有關嗎？

無論如何我無法找到問題，想到也許有人在這里可以看到它，謝謝

public class ZombieDefense extends JComponent implements Runnable   {

    //private Zombie zombie = new Zombie(this);
    private ImageIcon background = new ImageIcon(getClass().getResource("background.jpg"));
    protected Survivor survivor = new Survivor();
    private Barricade barricade = new Barricade();
    private GameScreen framePointer;
    protected ArrayList<Zombie> zombieArray = new ArrayList();
    protected ArrayList<Bullet> bulletArray = new ArrayList();
    Scanner in = new Scanner(System.in);
    Random random = new Random();
    Thread timer = new Thread(this);
    int currzomb = 0;
    int maxzomb = 10;
    int wave = 1;
    int kills = 0;
    int totalzomb = 10;
    int threadint = 2000;
    String name;
    Stopwatch time;

如果它與聲明以外的其他內容讓我知道，我將編輯並彈出代碼，再次感謝

Answer 1

protected ArrayList<Zombie> zombieArray = new ArrayList<Zombie>();
protected ArrayList<Bullet> bulletArray = new ArrayList<Bullet>();