Need Helps on Java Calculation Card Game

[Lim]

Hello, I am new to learning java, and i am trying to build the class for a calculation card game, unfortunately i can't get the public Card top() and Card takeTop() method in the Stock class.
Thanks!!
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this is the code for the Stock class:
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public class Stock
{
    private Deck deck = new Deck(52);
    private int X;
    private int Y;

    public Stock(Deck deck)
    {
        this.deck = deck;
    }
       
    /**
     * The number of cards in the stock(including the top card).
     * @return the number of cards.
     */
    public int numCardsRemaining()
    {
        return deck.numCardsRemaining();
    }
    
  
    /**
     * The top card of the stock.
     * @return the top card of the stock, or null if the stock is empty.
     * Acall to this method does not remove the card from the top but 
     * just returns a reference to it.
     */

    public Card top()
    {
        if(deck.numCardsRemaining()==0)
        {
            return null;
        }
        else
        {
            return deck.cards.get(0);
        }

    }
    
    /**
     * Take the top card from the stock.
     * @return the card that was on top of the stock or null if the stock was empty.
     * A call to this method reduces the number of cards remaining in the    stock by one.
     */
    public Card takeTop()
    {

    }
        
} 

in order to solve the problems you need to know Deck class too, but we can't modify this class as assignment requires.

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The code for Deck class:
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import java.util.*;
import java.awt.*;

public class Deck
{
    private java.util.List<Card> cards;      // The list of cards
    private static java.util.Random generator = null;
    
    /**
     * Constructor for a shuffled deck of cards.
     * @param seed the seed for the random number generator used to
     * shuffle the deck. A different unique shuffle is obtained for
     * each possible value of seed.
     */
    public Deck(long seed)
    {
        // Create a deck of cards in sorted order of suit then pip count.
        
        cards = new ArrayList<Card>();
        for (int suit = Card.SPADES; suit <= Card.CLUBS; suit++) {
            for (int pips = 1; pips <= Card.CARDS_IN_SUIT; pips++) {
                cards.add(new Card(suit, pips));
            }
        }
        
        // Now shuffle the deck, using a random number generator based
        // on the seed value given as a parameter.
        
        java.util.Random generator = new java.util.Random(seed); 
        java.util.Collections.shuffle(cards, generator);
    }
     
    public int numCardsRemaining()
    {
        return cards.size();
    }
    
    /**
     * Get the next card from the deck, reducing the number of cards
     * remaining in the deck by one.
     * @return the "top" card in the deck
     */
    public Card nextCard()
    {
        return cards.remove(0);
    }
    
    /**
     * Add the given card to the start (front) of the current deck.
     * @param card the card to be placed at the start of the deck
     */
    public void addAtStart(Card card)
    {
        cards.add(0, card);
    }
    
    /**
     * Add the given card to the end (back) of the current deck.
     * @param card the card to be placed on the end of the deck
     */
    public void addAtEnd(Card card)
    {
        cards.add(card);
    }
} 

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so my problems are how to get public Card top() and public Card takeTop() methods in the Stock class without modify the Deck class.

Thanks!