IT 114: Introduction to Java

IT 114: Introduction to Java
Class 41

Topics

New Material

Blackjack
The Card Class
The Deck Class
The Hand Class
Modifying Hand to Deal with Aces
Finishing the Hand Class
The Blackjack Class
Interacting with the User
Cards for the Dealer
Declaring a Winner
Contract for the Web

New Material

Blackjack

Today we will create a Java application that will play a game of Blackjack
Blackjack is one of one most popular card games in the world
You can find the rules here
Our app will consist of 4 classes
- Card - representing an individual card
- deck - representing a deck of 52 cards
- Hand - representing the cards dealt to a player
- BlackJack - a static class that runs the game
We will create each class in a step-by-step fashion

The Card Class

Card will have three fields
- rank - what kind of card it is (Ace, King, Queen, Jack, 10, etc.)
- suit - Clubs, Diamonds, Hearts or Spades
- score - the point value of the card
The constructor will set all these fields
But the point value of a card has to be calculated

So we will use the helper method set_score to handle this task

    public Card(String rank, String suit){
        this.rank = rank;
        this.suit = suit;
        this.score = set_score(rank);
    }

    private int set_score(String rank){
        if (rank.equals("Ace")){
            return 1;
        } else if (rank.equals("Jack") || rank.equals("Queen")  || rank.equals("King")){
            return 10;
        } else {
            return Integer.parseInt(rank);
        }
    }

Of course we need a toString method

    public String toString(){
        return rank + " of " + suit;
    }

Other classes will need to know the point value of each card so we need a score getter
```
    public int score(){
        return score;
    }
```
But Aces play a special role in Blackjack, so we need a getter for this to
```
    public boolean is_ace(){
        return rank.equals("Ace");
    }
```

Here is the test code

public class CardTest {
    public static void main (String[] args){
        String [] ranks = {"Ace", "2", "3", "4", "5", "6", "7",
                            "8", "9", "10", "Jack", "Queen", "King"};
        for (int i = 0; i < ranks.length; i++){
            Card c = new Card(ranks[i], "Spades");
            System.out.println(c + ", score: " + c.score() + ", is_ace: " + c.is_ace());  
        }
    }
}

$ java CardTest
Ace of Spades, score: 1, is_ace: true
2 of Spades, score: 2, is_ace: false
3 of Spades, score: 3, is_ace: false
4 of Spades, score: 4, is_ace: false
5 of Spades, score: 5, is_ace: false
6 of Spades, score: 6, is_ace: false
7 of Spades, score: 7, is_ace: false
8 of Spades, score: 8, is_ace: false
9 of Spades, score: 9, is_ace: false
10 of Spades, score: 10, is_ace: false
Jack of Spades, score: 10, is_ace: false
Queen of Spades, score: 10, is_ace: false
King of Spades, score: 10, is_ace: false

You can see the complete code for Card here

The Deck Class

A Deck consists of 52 card
Broken up into 4 suits
Of 13 ranks

So we need two constants

    private final String[] suits = {"Clubs", "Diamonds", "Hearts", "Spades"};
    private final String[] ranks = {"Ace", "2", "3", "4", "5", "6", "7",
                                     "8", "9", "10", "Jack", "Queen", "King"};

There is only one field

    private ArrayList<Card> deck = new ArrayList<>();

The constructor fills the deck with a nested for loop
The outer loop runs through the suits

While the inner loop creates the ranks

    public Deck (){
        for (int i = 0; i < suits.length; i++){
            for (int j =0; j < ranks.length; j++){
                deck.add(new Card(ranks[j], suits[i]));
            }
        }
    }

The toString method simply loops through the deck

    public String toString(){
        String value = "";
        for (int i = 0; i < deck.size(); i++){
            value += deck.get(i) + " ";
        }
        return value;
    }

The following code will test what we have done so far

$ java DeckTest1
Ace of Clubs 2 of Clubs 3 of Clubs 4 of Clubs 5 of Clubs 6 of Clubs 7 of Clubs 8 of Clubs ...

But a deck of cards needs to be shuffled before play can begins
So we need a shuffle method
It will work by creating an empty list
Randomly removing cards from the deck and adding them to the new list
Then copying the new list back to the empty deck

Here is the method

    public void shuffle(){
        Random rand = new Random();
        int size = deck.size();
        ArrayList<Card< temp = new ArrayList<>();
        while (size > 0){
            int i = rand.nextInt(size);
            Card c = deck.get(i);
            deck.remove(i);
            temp.add(c);
            size = deck.size();
        }
        for (int i = 0; i < temp.size(); i++){
            Card c = temp.get(i);
            deck.add(c);
        }
    }

And the test code

public class DeckTest2 {
    public static void main (String[] args){
        Deck2 d = new Deck2();
        System.out.println(d);
        d.shuffle();
        System.out.println("After shuffle");
        System.out.println(d);
    }
}

$ java DeckTest2
Ace of Clubs 2 of Clubs 3 of Clubs 4 of Clubs 5 of Clubs 6 of Clubs 7 of Clubs 8 of Clubs ...
After shuffle
Ace of Hearts 5 of Diamonds King of Clubs 7 of Spades 6 of Clubs King of Hearts Jack of Hearts ...

To complete this class we need a deal method
Which will take the next card from the deck

and return it to the calling method

    public Card deal_card(){
        Card card = deck.get(0);
        deck.remove(0);
        return card;
    }

We test it with the following

public class DeckTest2 {
    public static void main (String[] args){
        Deck2 d = new Deck2();
        System.out.println(d);
        d.shuffle();
        System.out.println("After shuffle");
        System.out.println(d);
    }
}

$ java DeckTest3
King of Diamonds 10 of Hearts 3 of Diamonds 7 of Spades Queen of Spades 2 of Clubs ...
Dealt card King of Diamonds
10 of Hearts 3 of Diamonds 7 of Spades Queen of Spades 2 of Clubs 6 of Hearts 4 of Clubs

You can see the complete code for Deck here

The Hand Class

The Hand class represent the cards an individual player is holding
The class has 4 fields
- cards - a list of the cards a player is holding
- player - the name of the player to whom the hand belongs
- has_ace - does the hand contain an Ace?
- has_ace - should all cards be face up
```
    private ArrayList<Card< cards;
    private String          player;
    private boolean         has_ace;
    private boolean         face_up;
```
This class is very complicated
So we will have to break up the work into several versions
Each one adding more functionality

Our first version will have a constructor

    public Hand (String player){
        this.cards   = new ArrayList<>();
        this.player  = player;
        this.has_ace = false;
        this.face_up = false;
    }

And a simple toString method that prints the player and the cards held
We will need to make this more complicated later

But for now we have

    public String toString(){
        String value = player + "\n" ;
        for (int i = 0; i < cards.size(); i++) {
            value += cards.get(i) + SPACER;
        }
        return value;
    }

SPACER is a constant

    private final String SPACER    = "   ";

Here is the test code for our first version of Hand

public class HandTest1 {
    public static void main (String[] args){
        Hand hand = new Hand("User");
        System.out.println(hand);
    }
}

$ java HandTest1
User

Now we need a method to add a card to the deck

    public void add_card(Card1 card){
        cards.add(card);
    }

And a method to return the point value of the entire hand
In Blackjack the Ace can have a value of either 1 or 11 points
But we will ignore this for now
So score will assign Aces a value of 1 point

And total the value of all cards

    public int score(){
        int total = 0;
        for (int i = 0; i < cards.size(); i++) {
            total += cards.get(i).score();
        }
        return total;
    }

Here is the test code

public class HandTest2 {
    public static void main (String[] args){
        Hand2 hand = new Hand2("User");
        Card1 c1 = new Card1("5", "Clubs");
        hand.add_card(c1);
        Card1 c2 = new Card1("King", "Spades");
        hand.add_card(c2);
        System.out.println(hand);
        System.out.println(hand.score());

    }
}

$ java HandTest2
User
5 of Clubs   King of Spades   
15

Now we need to modify the toString method to deal with the dealer]s hand
The first deal gives all plays two cards
For players other than the dealer, these cards are dealt face up
The dealer's first card is dealt face up
After the first deal, all the dealer's cards are shown face up
But the second card is dealt face down
So we have to modify toString when showing the dealer's hand

    public String toString(){
        String value = player + "\n" ;
        for (int i = 0; i < cards.size(); i++) {
            Card c = cards.get(i);
            if (player.equals("Dealer") && cards.size() == 2 && i == 1){ // second card
                value += FACE_DOWN + SPACER;
            } else {
                value += cards.get(i) + SPACER;
            }
        }
        return value;
    }

This code uses the constant FACE_DOWN

    private final String FACE_DOWN = "XXXX";

Here is the test

public class HandTest3 {
    public static void main (String[] args){
        Hand3 hand = new Hand3("Dealer");
        Card c1 = new Card("5", "Clubs");
        hand.add_card(c1);
        System.out.println(hand);
        System.out.println();
        Card c2 = new Card("King", "Spades");
        hand.add_card(c2);
        System.out.println(hand);
        System.out.println();
        Card c3 = new Card("10", "Spades");
        hand.add_card(c3);
        System.out.println(hand);
    }
}

$ java HandTest3
Dealer
5 of Clubs   

Dealer
5 of Clubs   XXXX   

Dealer
5 of Clubs   King of Spades   10 of Spades

You can see Hand as it is at this point here

Modifying Hand to Deal with Aces

Aces play a special role in Blackjack
Because their point value can be either 1 or 11
So we always have to know whether the hand has an Ace in it
We record this information in the has_ace field
```
    private boolean         has_ace;
```
Which is set to false by the constructor
We need to modify the add_card method

So it sets this field to true whenever and Ace is added

public void add_card(Card card){
        cards.add(card);
        if (card.is_ace()) {
            has_ace = true;
        }
    }

We can't test this change unless we also have a getter method for this field
So we will add it even though it will never be used in the game itself

Here is the test

public class HandTest4 {
    public static void main (String[] args){
        Hand4 hand = new Hand4("User");
        Card c1 = new Card("5", "Clubs");
        hand.add_card(c1);
        System.out.println(hand);
        System.out.println("Hand has ace? " + hand.has_ace());
        System.out.println();
        Card c2 = new Card("Ace", "Spades");
        hand.add_card(c2);
        System.out.println(hand);
        System.out.println("Hand has ace? " + hand.has_ace());
    }
}

$ java HandTest4
User
5 of Clubs   
Hand has ace? false

User
5 of Clubs   Ace of Spades   
Hand has ace? true

Now we have to modify score so it can deal with Aces
The basic ideas is that and Ace will be valued at 11 points
Unless the total points is over 12
In that case it will be valued as 1 point

Here is the code

    public int score(){
        int total = 0;
        for (int i = 0; i < cards.size(); i++) {
            total += cards.get(i).score();
        }
        if (has_ace && total < 12 && player.equals("User")){
            total += 10;
        }
        return total;
    }

And the test

public class HandTest5 {
    public static void main (String[] args){
        System.out.println("User hand");
        System.out.println();
        Hand5 hand1 = new Hand5("User");
        Card c1 = new Card("Ace", "Clubs");
        hand1.add_card(c1);
        System.out.println(hand1);
        System.out.println("Score: " + hand1.score());
        System.out.println();
        Card c2 = new Card("9", "Spades");
        hand1.add_card(c2);
        System.out.println(hand1);
        System.out.println("Score: " + hand1.score());
        System.out.println();
        Card c3 = new Card("6", "Spades");
        hand1.add_card(c3);
        System.out.println(hand1);
        System.out.println("Score: " + hand1.score());
        System.out.println();
        System.out.println("Dealer hand");
        Hand5 hand2 = new Hand5("Dealer");
        System.out.println();
        Card c4 = new Card("Ace", "Spades");
        hand2.add_card(c4);
        System.out.println(hand2);
        System.out.println("Score: " + hand2.score());
    }
}

$ java HandTest5
User hand

User
Ace of Clubs   
Score: 11

User
Ace of Clubs   9 of Spades   
Score: 20

User
Ace of Clubs   9 of Spades   6 of Spades   
Score: 16

Dealer hand

Dealer
Ace of Spades   
Score: 1

You can see the current version of Hand here

Finishing the Hand Class

One of the most important duties of Hand is to help determine when a player wins or looses
If a player's score is over 21, that player is said to be "busted"

So we need is_busted to tell us when that happens

    public boolean is_busted(){
        return score() > 21;
    }

Here is the test

public class HandTest6 {
    public static void main (String[] args){
        Hand hand = new Hand("Dealer");
        Card c1 = new Card("5", "Clubs");
        hand.add_card(c1);
        System.out.println(hand);
        System.out.println("Hand has ace? " + hand.has_ace());
        System.out.println("Score: " + hand.score());
        System.out.println("Busted? " + hand.is_busted());
        System.out.println();
        Card c2 = new Card("King", "Spades");
        hand.add_card(c2);
        System.out.println(hand);
        System.out.println("Hand has ace? " + hand.has_ace());
        System.out.println("Score: " + hand.score());
        System.out.println("Busted? " + hand.is_busted());
        System.out.println();
        Card c3 = new Card("Ace", "Spades");
        hand.add_card(c3);
        System.out.println(hand);
        System.out.println("Hand has ace? " + hand.has_ace());
        System.out.println("Score: " + hand.score());
        System.out.println("Busted? " + hand.is_busted());
        System.out.println();
        Card c4 = new Card("6", "Clubs");
        hand.add_card(c4);
        System.out.println(hand);
        System.out.println("Hand has ace? " + hand.has_ace());
        System.out.println("Score: " + hand.score());
        System.out.println("Busted? " + hand.is_busted());
    }
}

$ java HandTest6
Dealer
5 of Clubs   
Hand has ace? false
Score: 5
Busted? false

Dealer
5 of Clubs   XXXX   
Hand has ace? false
Score: 15
Busted? false

Dealer
5 of Clubs   King of Spades   Ace of Spades   
Hand has ace? true
Score: 16
Busted? false

Dealer
5 of Clubs   King of Spades   Ace of Spades   6 of Clubs   
Hand has ace? true
Score: 22
Busted? true

We need to make one last addition to this class
After the initial deal of two cards to each play
The user has to decide whether to take more cards
This is called a "hit"
Or to "stand" with the hand as it has been dealt
After the uses is satisfied with the hand they have got
It is the turn of the dealer
When this happens the dealer's face card is turned face up
So our game needs to be to be able to show the second card at this time
But the toString method will not show the 2nd card face up
Until another card has been added to the hand
So we need a way to force the 2nd card to be shown
To do this we need to add another field, face_up
```
    private boolean         face_up;
```
Which must be set to false by the constructor

Now we have to create a setter set_face_up

    public void set_face_up(){
        face_up = true;
    }

BlackJack, the class that runs the game will use this method
When it is the dealer's turn to get more cards
Finally, we have to modify toString
All we have to do is add an additional condition to the to the if statement

That prints the 2nd card face down

    public String toString(){
        String value = player + "\n" ;
        for (int i = 0; i < cards.size(); i++) {
            Card c = cards.get(i);
            if (player.equals("Dealer") && cards.size() == 2 && i == 1 
                && ! face_up){ 
                value += FACE_DOWN + SPACER;
            } else {
                value += cards.get(i) + SPACER;
            }
        }
        return value;
    }

Here is the test

public class HandTest7 {
    public static void main (String[] args){
        Hand7 hand = new Hand7("Dealer");
        Card c1 = new Card("5", "Clubs");
        hand.add_card(c1);
        Card c2 = new Card("King", "Spades");
        hand.add_card(c2);
        System.out.println("After first card dealt");
        System.out.println(hand);
        System.out.println();
        System.out.println("After set_face_up called");
        hand.set_face_up();
        System.out.println(hand);
    }
}

$ java HandTest7
After first card dealt
Dealer
5 of Clubs   XXXX   

After set_face_up called
Dealer
5 of Clubs   King of Spades

You can see the complete code for Hand here

The Blackjack Class

Now it is time to create the BlackJack class that runs the game
The first version
- Creates the deck
- Creates the user and dealer hands
- Shuffles the deck and prints it
- Prints both hands

Here is the code and a trial run

public class BlackJack1 {
    public static void main (String[] args){

        Deck deck = new Deck();
        Hand dealer_hand = new Hand("Dealer");
        Hand user_hand   = new Hand("User");
        deck.shuffle();
        System.out.println(deck);
        System.out.println();
        System.out.println(dealer_hand);
        System.out.println();
        System.out.println(user_hand);
    }
}

$ java BlackJack1
8 of Spades 3 of Diamonds 5 of Hearts 7 of Diamonds 4 of Spades 9 of Diamonds ...

Dealer


User

Now we need to deal 2 cards to each player

public class BlackJack2 {
    public static void main (String[] args){

        Deck deck = new Deck();
        Hand dealer_hand = new Hand("Dealer");
        Hand user_hand   = new Hand("User");
        deck.shuffle();
        System.out.println("Dealing two cards to each player");
        Card c1 = deck.deal_card();
        user_hand.add_card(c1);
        Card c2 = deck.deal_card();
        dealer_hand.add_card(c2);
        Card c3 = deck.deal_card();
        user_hand.add_card(c3);
        Card c4 = deck.deal_card();
        dealer_hand.add_card(c4);
        System.out.println();
        System.out.println(dealer_hand);
        System.out.println();
        System.out.println(user_hand);
    }
}

$ java BlackJack2
Dealing two cards to each player

Dealer
2 of Spades   XXXX   

User
4 of Clubs   Ace of Spades

The code is getting long
And it will only get longer
This will make it hard to read
And therefore hard to change
Lets move two sections of the code into helper methods
- setup_game
- initial_deal
Which are called by main
We'll also move the variables deck, dealer_hand and user_hand outside of main

So they can be used by any method

public class BlackJack3 {

    private static Deck deck;
    private static Hand dealer_hand;
    private static Hand user_hand;

    public static void main (String[] args){
        setup_game();
        initial_deal();
    }

    private static void setup_game(){
        deck = new Deck();
        dealer_hand = new Hand("Dealer");
        user_hand   = new Hand("User");
        deck.shuffle();
    }

    private static void initial_deal(){
        System.out.println("Dealing two cards to each player");
        Card c1 = deck.deal_card();
        user_hand.add_card(c1);
        Card c2 = deck.deal_card();
        dealer_hand.add_card(c2);
        Card c3 = deck.deal_card();
        user_hand.add_card(c3);
        Card c4 = deck.deal_card();
        dealer_hand.add_card(c4);
        System.out.println();
        System.out.println(dealer_hand);
        System.out.println();
        System.out.println(user_hand);
    }
}

$ java BlackJack3
Dealing two cards to each player

Dealer
7 of Diamonds   XXXX   

User
Queen of Clubs   Ace of Diamonds

Interacting with the User

Now we have to ask the user if they want more cards
We will create the method
The method will
- Create a Scanner
- Run a while loop looking for a valid response from the user
- It will loop until the user enters chex.py s (Stand) or h (Hit)
- Inside the loop it will prompt for input
- And get the user's reply

Here is the code

    private static String ask_user(){
        String reply = "";
        try {
            Scanner console = new Scanner(System.in);
            while (! reply.equals("h") && ! reply.equals("s")){
                System.out.println();
                System.out.println("H(it)  S(tand)");
                reply = console.nextLine();
                reply = reply.trim();
                reply = reply.toLowerCase();
            }
        } catch (Exception e){
            System.out.println(e);
        }
        return reply;
    }

The main method will call ask_user inside a while loop

The loop will stop when the user hits s for Stand

    public static void main (String[] args){
        setup_game();
        initial_deal();
        boolean user_done = false;
        while (! user_done){
            String action = ask_user();
            if (action.equals("s"))
                user_done = true;
        }
    }

Here is what happens when we run this code

$ java BlackJack4
Dealing two cards to each player

Dealer
7 of Hearts   XXXX   

User
8 of Hearts   7 of Clubs   

H(it)  S(tand)
h

H(it)  S(tand)
s

Now we need to add a card to the user's hand when the ask for a hit
We do this by added an else if clause to the if statement inside the while loop
A card is added to the user's hand if they want a hit

And then we show the user's hand

    public static void main (String[] args){
        setup_game();
        initial_deal();
        boolean user_done = false;
        while (! user_done){
            String action = ask_user();
            if (action.equals("s")){
                user_done = true;
            } else if (action.equals("h")) {
                Card c = deck.deal_card();
                user_hand.add_card(c);
                System.out.println(user_hand);
            }
        }
    }

Running this we get

$ java BlackJack5
Dealing two cards to each player

Dealer
7 of Hearts   XXXX   

User
6 of Hearts   3 of Diamonds   

H(it)  S(tand)
h
User
6 of Hearts   3 of Diamonds   Queen of Clubs   

H(it)  S(tand)
h
User
6 of Hearts   3 of Diamonds   Queen of Clubs   2 of Hearts   

H(it)  S(tand)
s

The code works, but the output is not what it should be
Instead of printing just the user's hand
We should print both hands
Since we will also have to do this when it is the dealer's turn
We should create a method to handle this chore

Here is show_hands

    private static void show_hands(){
        System.out.println();
        System.out.println(dealer_hand);
        System.out.println();
        System.out.println(user_hand);
    }

Which is called inside the while loop of the main method

public static void main (String[] args){
        setup_game();
        initial_deal();
        show_hands();
        boolean user_done = false;
        while (! user_done){
            String action = ask_user();
            if (action.equals("s")){
                user_done = true;
            } else if (action.equals("h")) {
                Card c = deck.deal_card();
                user_hand.add_card(c);
                show_hands();
            }
        }
        show_hands();
    }

Running this gives us the following

$ java BlackJack6
Dealing two cards to each player

Dealer
6 of Hearts   XXXX   

User
9 of Spades   Ace of Clubs   

H(it)  S(tand)
h

Dealer
6 of Hearts   XXXX   

User
9 of Spades   Ace of Clubs   King of Clubs   

H(it)  S(tand)
s

Dealer
6 of Hearts   XXXX   

User
9 of Spades   Ace of Clubs   King of Clubs

We have one more thing to do before moving on to the dealer
We can't know whether the user has won until the dealer draws cards
But after the user is finished we can tell if the user is busted by calling the is_busted method on user_hand
We add a call to is_busted to the condition running the while loop
```
while (! user_done && ! user_hand.is_busted()){
```

And add an if statement to the bottom of main

	if (user_hand.is_busted()){
            System.out.println();
            System.out.println("You're busted!!!");
        }

Here is the amended code in action

$ java BlackJack7
Dealing two cards to each player

Dealer
7 of Spades   XXXX   

User
10 of Diamonds   Queen of Hearts   

H(it)  S(tand)
h

Dealer
7 of Spades   XXXX   

User
10 of Diamonds   Queen of Hearts   King of Clubs   

Dealer
7 of Spades   XXXX   

User
10 of Diamonds   Queen of Hearts   King of Clubs   

You're busted!!!

You can see the current version of BlackJack here

Cards for the Dealer

It's now the dealer's turn to draw cards
But we need to the dealer's second card face up before doing this

So we will insert the following right after the user's while loop

        dealer_hand.set_face_up();
        show_hands();

Now we test

$ java BlackJack8
Dealing two cards to each player

Dealer
7 of Clubs   XXXX   

User
5 of Spades   8 of Spades   

H(it)  S(tand)
h

Dealer
7 of Clubs   XXXX   

User
5 of Spades   8 of Spades   6 of Clubs   

H(it)  S(tand)
s

Dealer
7 of Clubs   9 of Hearts   

User
5 of Spades   8 of Spades   6 of Clubs

There is no need for the dealer to take any cards if the user has busted
So we will put the code for giving cards to the dealer inside an else clause after testing whether the user went bust
In BlackJack, the user it dealt cards until his or her hand has at least 17 points without counting an Ace has having a value of 17 points

So we will use that as the condition for the while

        if (user_hand.is_busted()){
            System.out.println();
            System.out.println("You're busted!!!");
        } else {
            while (dealer_hand.score() < 17) {
                System.out.println("Dealer takes a card");
                Card c = deck.deal_card();
                dealer_hand.add_card(c);
                show_hands();
            }
        }

This is what we see when we run this code

$ java BlackJack9
Dealing two cards to each player

Dealer
7 of Clubs   XXXX   

User
4 of Hearts   6 of Clubs   

H(it)  S(tand)
h

Dealer
7 of Clubs   XXXX   

User
4 of Hearts   6 of Clubs   7 of Spades   

H(it)  S(tand)
s

Dealer
7 of Clubs   Ace of Clubs   

User
4 of Hearts   6 of Clubs   7 of Spades   
Dealer takes a card

Dealer
7 of Clubs   Ace of Clubs   10 of Hearts   

User
4 of Hearts   6 of Clubs   7 of Spades

We need one more thing before proceeding
If the user draws several cards they will all appear instantaneously in the output
We need to insert a slight delay between each card
The addition of cards to the dealer's hand becomes more obvious
This is not something we covered
And frankly, something I did not know how to do when writing the code

So I did some googling and came up with the code for the following method

    // copied from https://www.baeldung.com/java-delay-code-execution
    private static void sleep(int seconds){
        try {
            Thread.sleep(seconds * 1000);
        } catch (InterruptedException ie) {
            Thread.currentThread().interrupt();
        }
    }

Notice the comment before the function header
You should never claim the work of another as your own

This function is called twice in main

        if (user_hand.is_busted()){
            System.out.println();
            System.out.println("You're busted!!!");
        } else {
            sleep(1);
            while (dealer_hand.score() < 17) {
                System.out.println("Dealer takes a card");
                Card c = deck.deal_card();
                dealer_hand.add_card(c);
                show_hands();
                sleep(2);
            }
        }

You can see the current version of BlackJack here

Declaring a Winner

Now it's time to finish the game be seeing who won
The code already checks if the user has gone bust
So now we have to check whether the dealer has gone bust
If not, the user can only win if their score is higher than the dealer's

So we add the following after the dealer's while loop

            if (dealer_hand.is_busted()){
                System.out.println("Dealer busted\nUser wins!!");
            } else if (user_hand.score() > dealer_hand.score()) {
                System.out.println("User wins!!");
            } else {
                System.out.println("User loses");
            }

Here is what a game looks like

$ jv BlackJack.java 
Dealing two cards to each player

Dealer
2 of Hearts   XXXX   

User
4 of Hearts   9 of Diamonds   

H(it)  S(tand)
h

Dealer
2 of Hearts   XXXX   

User
4 of Hearts   9 of Diamonds   4 of Clubs   

H(it)  S(tand)
s

Dealer
2 of Hearts   8 of Diamonds   

User
4 of Hearts   9 of Diamonds   4 of Clubs   
Dealer takes a card

Dealer
2 of Hearts   8 of Diamonds   6 of Clubs   

User
4 of Hearts   9 of Diamonds   4 of Clubs   
Dealer takes a card

Dealer
2 of Hearts   8 of Diamonds   6 of Clubs   5 of Hearts   

User
4 of Hearts   9 of Diamonds   4 of Clubs   
User loses

You can see the final version of BlackJack here

Contract for the Web

Tim Berners-Lee is the man who created HTML
HTML stands for Hypertext Markup Language
It is the format that is used to create web pages
So you might say that Tim Berners-Lee is the man who invented the World Wide Web
He created the web to allow the free exchange of information
In the early days of the web it looked like something that would change the world for the better
Now it is debatable whether the web does more harm than good
Bigots of various sorts use the web and its platforms to spread hatred
Foreign governments spread lies to undermine our democracy
Crackpot ideas proliferate
- The earth is flat
- Vaccines cause autism
All this has been hard for Tim Berner-Lee to watch
Rescue the web he has launches an initiative called the Contract for the Web
It is the result of many months of consultation with many people in government, academia, and not-profits
Here are it's fundamental principles
- Everyone can connect to the Internet
- Keep all of the Internet available, all of the time
- Respect and protect people's fundamental online privacy and data rights
- Make the Internet affordable and accessible to everyone
- Respect and protect people's privacy and personal data to build online trust
- Develop technologies that support the best in humanity and challenge the worst
- Be creators and collaborators on the Web
- Build strong communities that civil discourse and human dignity
- Fight for the Web
Tim has asked all of us to endorse the Contract
I have done this on the Contract Web site
I would urge all of you to do so too
Rescuing the web from it's most toxic elements will take some time
But all of us must do what we can to make the web a better place
If you are not part of the solution, you are part of the problem