How to include method to update AI player's memory with guesses in random number guessing game so they don't guess the same number again?

I am writing a program that basically is a guessing game that makes two players guess a random number between 50 and 90--there will be three files (GameLauncher, GuessGame, Player)--now I am trying to make each player both not guess the same number and also not guess the same number later. I am a bit stuck at how to make that happen--it seems like there is an Array of all guesses remembered, but I am a bit lost at how to incorporate in the GuessGame file to make sure the players remember to not guess the same number. Any help would be really great! I have written the program here--I might have to add the updateMemory code in the GuessGame file instead as well:

    public class Player {

        ArrayList myMemory = new ArrayList();
        //helps player remember other numbers


        public int guess(){
            int myGuess; 
            myMemory.add(0);

           // myGuess = 50 + (int) (Math.random () * 40);
            myGuess = 50 + (int) (Math.random () * 40);
            while(myMemory.contains(myGuess)) {
           // myGuess = 50 + (int) (Math.random () * 40);
            myGuess = 50 + (int) (Math.random () * 40);
            }

            return myGuess;

        }
       public void updateMemory(int number) 
       { 
           myMemory.add(number);


       }



    }





public class GuessGame {


    private int secretNumber = 50 + (int) (Math.random () * 40);
    Player playerOne = new Player(); 
    Player playerTwo = new Player(); 

    int playerOneGuess;
    int playerTwoGuess;

    boolean playerOneisRight = false; 
    boolean playerTwoisRight = false;

    void start(){
        while(true) {

           playerOneGuess  = playerOne.guess(); 
           playerTwoGuess = playerTwo.guess();




    System.out.println("Player One guessed: " + playerOneGuess);
    System.out.println("Player Two guessed: " + playerTwoGuess);

    if (playerOneGuess == secretNumber) {
        playerOneisRight = true;
        System.out.println("Player One guessed correctly!");
        break;
}
    else if (playerTwoGuess == secretNumber){
        playerTwoisRight = true;
        System.out.println("Player Two guessed correctly!");
        break;
         }
    else {

        System.out.println("Sorry, nobody guessed right. Try again! "); 
        playerOneGuess++;
        playerTwoGuess++;

    }

  }

 }

}

public class GameLauncher {
    public static void main (String [] args) {
        GuessGame myGame = new GuessGame();
        myGame.start();

}