问在Java中，一个对象在我杀死它的持有者之后还活着吗？

EN

public void startMainWindow(int levelIndex, int levelsDone, int score) {
    gameGui = null; //desperate attempt
    highScoreGui = null;
    mainMenuGui = null;
    spaceGui = null;
    gameLogic = null;
    System.gc();

    gameLogic = new GameLogic(_sprites, _levels[levelIndex], levelsDone, score);

    gameGui = new MainWindowGui(this, gameLogic, _sprites, _levels);
}

public void startHighscoreGui(int score, String time) {
        gameGui = null;
        highScoreGui = null;
        mainMenuGui = null;
        spaceGui = null;
        gameLogic = null;
        System.gc();

        highScoreGui = new HighscoreGui(this, score, time);
    }

public class MainWindow extends JFrame implements KeyListener {

    private PacmanGame _game;
    private GameLogic _gameLogic;
    private GamePanel _gamePanel; //JPanel
    private ToolbarPanel _toolbarPanel; //JPanel
    private Sprite[] _sprites;
    private Level[] _levels;

    public MainWindow(PacmanGame game, GameLogic gameLogic, Sprite[] sprites, Level[] levels) {
        // create our window
        super("Pacman");

        // initialize fields
        _game = game;
        _sprites = sprites;
        _gameLogic = gameLogic;
        _levels = levels;
        this._gamePanel = new GamePanel(_gameLogic, _sprites);
        this._toolbarPanel = new ToolbarPanel(_gameLogic, sprites, this);
        ...
    }

    public void playerWon(String time) {
        Level levelObj = _gameLogic.getLevelObject();
        int nextLevelIndex = (levelObj.getNum()) % 3;

        if(_gameLogic.getLevel() == 3) //done!
        {
            this.dispose();
            _game.startHighscoreGui(_gameLogic.getScore(), time);
        }
        else //next level
        {
            _gameLogic.nextLevel(_levels[nextLevelIndex]);
        }
    }