了解Java中的方法/类调用

我正在尝试制作一个非常基本的Black Jack游戏，我将它分为三个简单的类，但是我对Java还是很陌生，我是一个糟糕的程序员，但是我需要学习它才能上班。我在理解如何调用方法和类时遇到一些重大困难。我弄清楚了游戏的基本结构，例如如何创建纸牌以及如何进入游戏和退出游戏。我只是不知道游戏本身。这是我到目前为止创建的。请任何建议和指示，以便我能明白，这真是我绝望。

BlackJack.java

import java.util.*;

public class BlackJack4 {

    public static void main(String[] args) {
    // write your code here

        Scanner keyboard = new Scanner(System.in);
        Scanner scan = new Scanner(System.in);

        String playGame = "";

        System.out.print("Wanna play some BlackJack? \n");
        System.out.print("Type yes or no \n");

        playGame = keyboard.nextLine();

        if (playGame.equals ("yes"))
        {
            /*
            This is the area I need help in figuring out. 
             */
        }
        else if (playGame.equals("no")) //Player decided to no play the game
        {
            System.out.print("Thank you for playing with us today.\n");
            System.out.print("To exit the game please press enter.");
            scan.nextLine();
            System.exit(0);
        }
        else
        {
            System.out.print("Sorry you did something wrong. Please try again.\n");
            System.out.print("To exit the game please press enter.");
            scan.nextLine();
            System.exit(0);
        }
    }
}

Deck.java

import java.util.*;

public class Deck {
    ArrayList<Cards> cards = new ArrayList<Cards>();

    String[] Suits = { "Clubs", "Diamonds", "Hearts", "Spades"};
    String[] Ranks = {null, "A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"};

    public Deck() {
        int d = Suits.length * Ranks.length;

        String[] deck = new String[d];
        for (int i = 0; i < Ranks.length; i++) {
            for (int j = 0; j < Suits.length; j++) {
                deck[Suits.length * i + j] = Ranks[i] + " of " + Suits[j];
            }
        }
    }

    public void shuffle(){//shuffle the deck when its created
        Collections.shuffle(this.cards);
    }
}

Cards.java

public class Cards {
    private String suit;
    private String rank;

    public Cards(){}

    public Cards(String suit, String rank){
        this.suit = suit;
        this.rank = rank;
    }

    public  String getSuit(){
        return suit;
    }
    /* public void setSuit(String suit){
        this.suit = suit;
    }*/
    public String getRank(){
        return rank;
    }
    /*
    public void setRank(String value){
        this.rank = rank;
    }*/
    @Override
    public String toString() {
        return String.format("%s of %s", rank, suit);
    }
}