我正在用java创建一个hilo猜谜游戏。到目前为止，我所拥有的一切都按预期运行，除了在最后提示用户再次玩时，随机数与上一个游戏相同。如何使代码在用户选择玩新游戏时产生一个新的随机数？

int answer  = (int)(Math.random() * 100 + 1);
    int guess = 0;
    int guessCount = 0;
    boolean playGame = true;
    String restart;
    Scanner scan = new Scanner(System.in);

while(playGame == true)
{
    while (playGame == true) 
    {
        System.out.println("Enter a number between 1 and 100: ");
        guess = scan.nextInt();
        guessCount ++;

        System.out.println(answer);

        if (guess < 1 || guess > 100) 
        {
            System.out.println("You have entered an invalid number.");
            guessCount --;
        } else if (guess == answer) 
        {
            System.out.println("Correct! Great guess! It took you " + guessCount + " tries!");
            break;
        } else if (guess > answer) 
        {
            System.out.println("You've guessed too high! Guess again: ");
        } else if (guess < answer)
        {
            System.out.println("You've guessed too low! Guess again: ");
        }
    }

    System.out.println("Would you like to play again? Y/N");
    restart = scan.next();

    if (restart.equalsIgnoreCase("Y")) 
    {
        playGame = true;
    } else if(restart.equalsIgnoreCase("N"))
    {
        System.out.println("Thank you for playing!");
        break;
    }
}