Have been attempting to create a class called CardDeck to shuffle card objects created in a different class (called DeckOfCard, sorry for the confusion, not well named) but have run out of ideas of how to accomplish this.
here is what I have come up with, I've included the original class DeckOfCards as well, any help/ advice is welcomed and appreciated!
//CODE FOR CARD OBJECT//
public final static int ace = 1, two= 2,three=3, four=4, five=5, six=6, seven =7, eight=8, nine=9, ten=10, jack= 11, queen=12, king=13;
public final static int diamonds= 1, clubs= 2, spades= 3, hearts=4;
private final static int numberOfFaces = 13;
private final static int numberOfSuits = 4;
private int face, suit;
private String faceValue, suitName;
//create a random card
public DeckOfCards()
{
face= (int)(Math.random() * numberOfFaces);
setFaceValue();
suit= (int) (Math.random() * numberOfSuits);
setSuitName();
}
//sets the string representation of each face value to its coorspdoing numeric value
private void setFaceValue()
{
switch(face)
{
case ace:
faceValue= "Ace";
break;
case two:
faceValue= "Two";
break;
case three:
faceValue= "Three";
break;
case four:
faceValue= "Four";
break;
case five:
faceValue = "Five";
break;
case six:
faceValue = "Six";
break;
case seven:
faceValue= "Seven";
break;
case eight:
faceValue= "Eight";
break;
case nine:
faceValue= "Nine";
break;
case ten:
faceValue= "Ten";
break;
case jack:
faceValue= "Jack";
break;
case queen:
faceValue= "Queen";
break;
case king:
faceValue= "King";
break;
}
}
//set the string representation of each suit
private void setSuitName()
{
switch(suit)
{
case diamonds:
suitName = "Diamonds";
break;
case clubs:
suitName= "Clubs";
break;
case spades:
suitName = "Spades";
break;
case hearts:
suitName = "Hearts";
break;
}
}
public String getFaceValue()
{
return faceValue;
}
public String getSuitName()
{
return suitName;
}
public String toString()
{
return faceValue+ " of " +suitName;
}
}
And Here is my current code... It's not much but this is as close as I have been able to get thus far:
import java.util.Random;
public class CardDeck
{
private DeckOfCards[] cards;
//create new deck of cards
public CardDeck()
{
cards = new DeckOfCards[52];
int index= 0;
int[] cardTypes = {DeckOfCards.ace, DeckOfCards.diamonds, DeckOfCards.spades, DeckOfCards.hearts};
for(int cardType : cardTypes)
{
for(int i = 1; i<=13; i++)
{
DeckOfCards card = new DeckOfCards();
cards[index++]= card;
}
}
}
//create shuffle method, use loop to generate random suit and random faceValue
public void shuffle()
{
System.out.println("Suffuling cards");
int loopCount = 53;
while (loopCount > 0) {
double index1 = Math.random();
double index2 = Math.random();
DeckOfCards temp = cards[index1];
cards[index1] = cards[index2];
cards[index2] = temp;
loopCount--;
}
}
}
Define a enum types for the rank and the suit. This provides type safety so that you don't accidentally pass a rank for a suit parameter or vice versa. The enumerated values also make good keys to use in maps to define scoring systems for different games and so on. Note also that enums can have properties and methods, so you can add user friendly names for values that way.
Then create a Card type that has a rank and a suit.
Iterate over the ranks, and for each rank, iterate over the suits. Create a new Card for each combination of rank and suit, and add it to a List; this is your deck. When your deck is built, you can shuffle it with a convenience method in Collections.
public final class Card {
public enum Rank {
ACE, DEUCE, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING
}
public enum Suit {
SPADES, HEARTS, DIAMOND, CLUBS
}
private final Rank rank;
private final Suit suit;
public Card(Rank rank, Suit suit) {
this.rank = Objects.requireNonNull(rank);
this.suit = Objects.requireNonNull(suit);
}
public Rank getRank() {
return rank;
}
public Suit getSuit() {
return suit;
}
#Override
public boolean equals(Object obj) {
if (obj == this) return true;
if (!(obj instanceof Card)) return false;
Card that = (Card) obj;
return (getRank() == that.getRank()) && (getSuit() == that.getSuit());
}
#Override
public int hashCode() {
return getRank().hashCode() * 31 + getSuit().hashCode();
}
#Override
public String toString() {
return getRank() + " of " + getSuit();
}
}
public class Deck {
private final List<? extends Card> cards;
public Deck(Collection<? extends Card> cards) {
this.cards = new ArrayList<>(cards);
}
public void shuffle(Random random) {
if (random == null) random = ThreadLocalRandom.current();
Collections.shuffle(cards, random);
}
public static Deck newStandardDeck() {
List<Card> cards = new ArrayList<>();
for (Card.Rank rank : Card.Rank.values()) {
for (Card.Suit suit : Card.Suit.values()) {
cards.add(new Card(rank, suit));
}
}
return new Deck(cards);
}
}
Your issue lies here:
double index1 = Math.random();
double index2 = Math.random();
Math.random() returns a double float between 0 and 1.
Try this instead:
Random r = new Random();
while(loopCount > 0) {
int index1 = r.nextInt(cards.length);
int index2 = r.nextInt(cards.length);
So there's some big issues with your code structure but i salvaged this.
The easiest solution is to create a sorted list of cards, one for each suite and value and then set each card to a random index. This will perform that on a field 'cards'
// create shuffle method, use loop to generate random suit and random faceValue
public void shuffle() {
System.out.println("Suffuling cards");
int loopCount = 0;
ArrayList<DeckOfCards> inOrder = new ArrayList<DeckOfCards>();
for(int i = 0; i < 54; i++)
{
inOrder.add(cards[i]);
}
DeckOfCards[] shuffled = new DeckOfCards[54];
for(int i = 0; i < 54; i++)
{
//Math.random()*size of inOrder will give you a double between 0 and size of in order.
//Round this down and convert to an int and you have a random index!
int randCardIndex = (int) (Math.floor(Math.random()*inOrder.size()));
//Grab the card and add it to the shuffled deck in the current position
shuffled[i] = inOrder.get(randCardIndex);
//Remove this card so it can no longer be grabbed
inOrder.remove(randCardIndex);
}
cards = shuffled;
}
Please change the name to Card instead of DeckOfCards. A list of Card objects becomes a deck of cards, so you don't want to call the object itself the deck.
The random function should follow a similar approach as the constructor of DeckOfCards in which your multiplier should be applied on top of the random number and be casted into an int. After that, your code should work fine. Card size 52 should be stored as a global private variable. Never use "magic numbers" without storing them in a variable and calling that variable. Both index1 and index2 should be the following:
double index1 = Math.random()*NUM_CARDS
Below your private array have the following variable: private final int NUM_CARDS = 52
Otherwise you are on the right track and the shuffling mechanism is good. It's just the random index generation gets a decimal number between 0 to 1.
When you have to debug, use the printing your variables technique. In this case, print out every value of index1 and index2 and check whether those values are being generated as intended. You can also try a less beginner friendly method called debug mode (cockroach icon) and double click on a line number to set a breakpoint at which you want the execution to pause and you can view all the variables stored in memory at that point of your code.
Related
Here is my issue, I have created this class which is incomplete because I am having issues on two levels. I might just be tired...so bear with me please.
I am having an issue trying to resolve having 5 random cards generate and not just 1 but more important no duplicates.
I am still fairly new to this but every time I try to add my main it says all my variables haven't been initialized. WTF...This is the biggest program/ first class I have had to write and I am just stuck.
help please
import java.util.*;
public class Card
{
private int suit; // Initializes two variables for the card
private int value;
public Card() // constructor of the card that creates a random suit and value for the card
{
Random num = new Random();
suit = num.nextInt(4);
value = num.nextInt(13)+1;
}
public Card(int Card_suit, int Card_value) // constructor of the card that takes an int representing suit and value
{
suit = Card_suit;
value = Card_value;
}
public int getValue() // returns the numeric value of the card
{
return value;
}
public int getSuit() // returns the numeric coded value of the card' suit
{
return suit;
}
public String getSuitAsString() // Return a String representing the card's suit.
// (If the card's suit is invalid, "??" is returned.)
{
switch ( suit )
{
case 3: return "Spades";
case 2: return "Hearts";
case 1: return "Diamonds";
case 0: return "Clubs";
default: return "??";
}
}
public String getValueAsString() // Return a String representing the card's value.
// If the card's value i// Compares the value of the card, to the value, as an int, of another card
// returns true if value > other card, false if not invalid, "??" is returned.
{
switch ( value )
{
case 1: return "Ace";
case 2: return "2";
case 3: return "3";
case 4: return "4";
case 5: return "5";
case 6: return "6";
case 7: return "7";
case 8: return "8";
case 9: return "9";
case 10: return "10";
case 11: return "Jack";
case 12: return "Queen";
case 13: return "King";
default: return "??";
}
}
public String toString() // overrides toString method,
{
return getValueAsString() + " of " + getSuitAsString(); // Return a String representation of this card, such as
// "10 of Hearts" or "Queen of Spades".
}
public boolean compareValue(int cardOther)
{
return value > cardOther;
}
}
IMO You have two options to get rid of problem-1:
Override equals method based on suit_value combo and every time you create an object of it put it in a list after checking if that already exist or not. If it exists create a new one else keep it and put it in the list.
Similar as before but instead of List use a Map with key suit+value -> respective Obj.
In order to not create duplicate cards, you need to keep track of what cards are available. This makes me think of a Deck:
class Deck
{
List<Card> cards;
public Deck()
{
cards = new ArrayList<Card>();
for (int suit = 0; suit < 4; suit++)
for (int value = 0; value < 13; value++)
cards.add(new Card(suit, value);
}
public void shuffle()
{
Collections.shuffle(cards);
}
public Card draw()
{
if (list.size() == 0)
{
// There's no cards left in the deck, you could
// return null or throw an exception
return null;
}
// Otherwise, take the last card out of the deck and return it
return cards.remove(list.size() - 1);
}
}
In your main method, create a deck, shuffle it, and draw 5 cards.
public static void main(String[] args)
{
Deck deck = new Deck();
deck.shuffle();
for (int i = 0; i < 5; i++)
{
Card card = deck.draw();
System.out.println(card);
}
}
In a Java program I am trying to return the largest value card in a deck.
Diamonds are the lowest valued suit. Then clubs, then hearts and finally spades have the largest value. As you can see I have a section of code that simply says largest = in the findLargest methods. I am not sure where to go with the rest of this method.
public class Card {
private int number;
private String suit;
/*
* Randomly creates a card numbered 1 to 13 (ace = 1!) and labelled "Hearts","Clubs","Diamonds" or "Spades".
*/
public Card() {
double randomNum = Math.random() * 4.0;
if (randomNum < 1.0)
suit = "Hearts";
else if (randomNum < 2.0)
suit = "Clubs";
else if (randomNum < 3.0)
suit = "Diamonds";
else
suit = "Spades";
randomNum = Math.random() * 13.0;
number = (int) randomNum + 1;
}
/*
* Creates a card with specified number and suit
*/
public Card (int n, String s) {
number = n;
suit = s;
}
public int getNumber() {
return number;
}
public String getSuit () {
return suit;
}
public String cardString() {
// System.out.println(number + " " + suit);
String stringNum = "";
switch (number) {
case 1:
stringNum = "Ace";
break;
case 2:
stringNum = "Two";
break;
case 3:
stringNum = "Three";
break;
case 4:
stringNum = "Four";
break;
case 5:
stringNum = "Five";
break;
case 6:
stringNum = "Six";
break;
case 7:
stringNum = "Seven";
break;
case 8:
stringNum = "Eight";
break;
case 9:
stringNum = "Nine";
break;
case 10:
stringNum = "Ten";
break;
case 11:
stringNum = "Jack";
break;
case 12:
stringNum = "Queen";
break;
case 13:
stringNum = "King";
break;
default:
System.out.println("Error in Card - illegal number");
}
return stringNum + " of " + suit;
}
}
public class PackCards {
private ArrayList<Card> pack;
/*
* Create a random pack of size n
*/
public PackCards(int n) {
Card c;
pack = new ArrayList<Card>();
for (int i = 1; i <= n; i++) {
c = new Card();
pack.add(c);
}
}
public void printPack() {
for (Card c : pack) {
System.out.println(c.cardString());
}
}
public Card findLargest() {
if ( c.getNumber() > largest.getNumber() )
largest =
else if (c.getNumber() == largest.getNumber() ) {
if (largest.getSuit().equals("Diamonds"))
largest = largest.getNumber;
}
else if (c.getNumber() == largest.getNumber() ) {
if (largest.getSuit().equals("Clubs"))
largest = largest.getNumber;
}
else if (c.getNumber() == largest.getNumber() ) {
if (largest.getSuit().equals("Hearts"))
largest = largest.getNumber;
}
else return;
}
I would simplify the code to make it easier to see what you are trying to achieve. In Java 8 you can do.
import java.util.Random;
public class Card {
enum Suit {
// must be in increasing order.
Spades, Diamonds, Clubs, Hearts
}
static final Suit[] SUITS = Suit.values();
private final int number;
private final Suit suit;
/*
* Randomly creates a card numbered 1 to 13 (ace = 1!) and labelled "Hearts","Clubs","Diamonds" or "Spades".
*/
public Card() {
Random rand = new Random();
suit = SUITS[rand.nextInt(SUITS.length)];
number = rand.nextInt(13) + 1;
}
public int getNumber() {
return number;
}
public Suit getSuit() {
return suit;
}
static final String[] NAMES = ",Ace,Two,Three,Four,Five,Six,Seven,Eight,Nine,Ten,Jack,Queen,King".split(",");
public String cardString() {
assert number > 1 && number < NAMES.length;
return NAMES[number] + " of " + suit;
}
}
This simplifies your pack as well
public class PackOfCards {
private final List<Card> cards;
public PackOfCards(int size) {
// note duplicates are possible, i.e. ever card could be the same.
cards = IntStream.range(0, size)
.mapToObj(n -> new Card())
.collect(Collectors.toList());
}
public Card findLargest() {
return cards.stream().max(Comparator.comparing(Card::getNumber)
.thenComparing(Card::getSuit)).get();
}
}
You can change the Card class to implements the Comparable interface. For example:
public class Card implements Comparable<Card> {
....// your current implementation for the Card class
public int compareTo(Card another) {
if (this.suit.compareTo(another.suit) == 0) {
if (this.number < another.number) {
return -1;
} else if (this.number > another.number) {
return 1;
} else {
return 0;
}
} else if (this.suit.compareTo("Diamonds") == 0) {
// Diamonds being the lowest valued suit ...
return -1;
} else if (this.suit.compareTo("Clubs") == 0) {
// ... then Clubs ...
if (another.suit.compareTo("Diamonds") == 0) {
return 1;
} else {
return -1;
}
} else if (this.suit.compareTo("Hearts") == 0) {
// ... Hearts ...
if (another.suit.compareTo("Spades") == 0) {
return -1;
} else {
return 1;
}
} else {
// ... and largest values, Spades
return 1;
}
}
}
Then, you can modify the PackCards to store the cards in an ordered collection. For example:
pack = new TreeSet<Card>();
That way, the cards in the pack are ordered, and the last one is the largest.
If you want to mantain the order in wich the cards was added to the list, you can obtain the largest one in this way:
largest = Collections.max(pack);
For this sort of work, you want to leverage the object-oriented nature of Java and utilize Enums for both the FaceValue and the Suit. Enums are 'naturally ordered' in the order you list them, making your construction and string output a LOT easier:
public class Card implements Comparable<Card> {
private FaceValue faceValue;
private Suit suit;
/*
* Randomly creates a card numbered 1 to 13 (ace = 1!)
* labelled "Hearts","Clubs","Diamonds" or "Spades".
*/
public Card() {
int randomSuit = (int)Math.floor(Math.random() * 4.0); //Number between 0 and 3, inclusive.
int randomFace = (int)Math.floor(Math.random() * 13.0);
this.faceValue = FaceValue.values()[randomFace];
this.suit = Suit.values()[randomSuit];
}
public Card(FaceValue value, Suit suit) {
this.faceValue = value;
this.suit = suit;
}
// TODO Constructor that convert ints and strings to proper enums and call previous constructor
public int compareTo(Card that) {
int comparison = this.suit.compareTo(that.suit);
return (comparison != 0) ? comparison : this.faceValue.compareTo(that.faceValue);
}
public String cardString() {
return this.faceValue + " of " + this.suit;
}
public enum Suit{
DIAMOND, CLUB, HEART, SPADE;
}
public enum FaceValue {
ACE, ONE, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING;
} // You can modify this enum if you need to give back something more specific as the string value.
}
Then for your Deck you can simplify things as well by choosing a good data structure, in this case a TreeSet, which will automatically use the compareTo function you've provided for cards to sort the cards.:
public class Deck {
//By using a Set we eliminate duplicates
private final TreeSet<Card> cards;
public Deck(int size) {
cards = Sets.newTreeSet(IntStream.range(0, size)
.mapToObj(n -> new Card())
.collect(Collectors.toList());
}
//Because this is a TreeSet, finding the largest value is trivial.
public Card findLargest() {
return this.cards.last();
}
}
If you need special strings for the cards in your deck, you would do the following modification to FaceValue:
public enum FaceValue {
ACE {
public String toString() { return "Ace"; }
},
ONE {
public String toString() { return "One"; }
},
... // Fill out the rest in the same manner.
KING {
public String toString() { return "King"; }
}
}
Remember that in Object-Oriented programming, the number one rule is that an object should know how behave. Thus, if you find yourself writing a switch statement, chances are you can defer the behavior to the objects themselves. In this case, you need to create sub-objects (the FaceValue and Suit enums) that you assign to a given card. The card asks those sub parts how they are ordered, and how they should respond to a toString request.
I'm trying to finish this homework but it has been a little bit challenging so far, I'm quite new at java:
1). I have to create enums to replace the named constants for rank and suit in Card.java.
2).Make the changes necessary in Deck.java and DisplayDeck.java so they will work with the new Card.java.
This is my code so far for my three classes: Card.java, Deck.java and DisplayDeck.java
Original Card.java
public class Card {
private final int rank;
private final int suit;
// Kinds of suits
public final static int DIAMONDS = 1;
public final static int CLUBS = 2;
public final static int HEARTS = 3;
public final static int SPADES = 4;
// Kinds of ranks
public final static int ACE = 1;
public final static int DEUCE = 2;
public final static int THREE = 3;
public final static int FOUR = 4;
public final static int FIVE = 5;
public final static int SIX = 6;
public final static int SEVEN = 7;
public final static int EIGHT = 8;
public final static int NINE = 9;
public final static int TEN = 10;
public final static int JACK = 11;
public final static int QUEEN = 12;
public final static int KING = 13;
public Card(int rank, int suit) {
assert isValidRank(rank);
assert isValidSuit(suit);
this.rank = rank;
this.suit = suit;
}
public int getSuit() {
return suit;
}
public int getRank() {
return rank;
}
public static boolean isValidRank(int rank) {
return ACE <= rank && rank <= KING;
}
public static boolean isValidSuit(int suit) {
return DIAMONDS <= suit && suit <= SPADES;
}
public static String rankToString(int rank) {
switch (rank) {
case ACE:
return "Ace";
case DEUCE:
return "Deuce";
case THREE:
return "Three";
case FOUR:
return "Four";
case FIVE:
return "Five";
case SIX:
return "Six";
case SEVEN:
return "Seven";
case EIGHT:
return "Eight";
case NINE:
return "Nine";
case TEN:
return "Ten";
case JACK:
return "Jack";
case QUEEN:
return "Queen";
case KING:
return "King";
default:
//Handle an illegal argument. There are generally two
//ways to handle invalid arguments, throwing an exception
//(see the section on Handling Exceptions) or return null
return null;
}
}
public static String suitToString(int suit) {
switch (suit) {
case DIAMONDS:
return "Diamonds";
case CLUBS:
return "Clubs";
case HEARTS:
return "Hearts";
case SPADES:
return "Spades";
default:
return null;
}
}
public static void main(String[] args) {
// must run program with -ea flag (java -ea ..) to
// use assert statements
assert rankToString(ACE) == "Ace";
assert rankToString(DEUCE) == "Deuce";
assert rankToString(THREE) == "Three";
assert rankToString(FOUR) == "Four";
assert rankToString(FIVE) == "Five";
assert rankToString(SIX) == "Six";
assert rankToString(SEVEN) == "Seven";
assert rankToString(EIGHT) == "Eight";
assert rankToString(NINE) == "Nine";
assert rankToString(TEN) == "Ten";
assert rankToString(JACK) == "Jack";
assert rankToString(QUEEN) == "Queen";
assert rankToString(KING) == "King";
assert suitToString(DIAMONDS) == "Diamonds";
assert suitToString(CLUBS) == "Clubs";
assert suitToString(HEARTS) == "Hearts";
assert suitToString(SPADES) == "Spades";
}
}
My modified Card.java so far:
public class Card {
public enum Suit
{
DIAMONDS(1),
CLUBS(2),
HEARTS(3),
SPADES(4);
private final int suit;
private Suit(int suit)
{
this.suit = suit;
}
public int getSuit()
{
return suit;
}
} //end enum suit
public enum Rank
{
ACE(1),
DEUCE(2),
THREE(3),
FOUR(4),
FIVE(5),
SIX(6),
SEVEN(7),
EIGHT(8),
NINE(9),
TEN(10),
JACK(11),
QUEEN(12),
KING(13);
private final int rank;
private Rank(int rank)
{
this.rank = rank;
}
public int getRank()
{
return rank;
}
}//end enum rank
public static String rankToString(Rank rank) {
switch (rank) {
case ACE:
return "Ace";
case DEUCE:
return "Deuce";
case THREE:
return "Three";
case FOUR:
return "Four";
case FIVE:
return "Five";
case SIX:
return "Six";
case SEVEN:
return "Seven";
case EIGHT:
return "Eight";
case NINE:
return "Nine";
case TEN:
return "Ten";
case JACK:
return "Jack";
case QUEEN:
return "Queen";
case KING:
return "King";
default:
//Handle an illegal argument. There are generally two
//ways to handle invalid arguments, throwing an exception
//(see the section on Handling Exceptions) or return null
return null;
}
}
public static String suitToString(Suit suit) {
switch (suit) {
case DIAMONDS:
return "Diamonds";
case CLUBS:
return "Clubs";
case HEARTS:
return "Hearts";
case SPADES:
return "Spades";
default:
return null;
}
}
}//end class
And this are the original Deck.java and DisplayDeck.java:
Original Deck.java
import java.util.*;
public class Deck {
public static int numSuits = 4;
public static int numRanks = 13;
public static int numCards = numSuits * numRanks;
private Card[][] cards;
public Deck() {
cards = new Card[numSuits][numRanks];
for (int suit = Card.DIAMONDS; suit <= Card.SPADES; suit++) {
for (int rank = Card.ACE; rank <= Card.KING; rank++) {
cards[suit-1][rank-1] = new Card(rank, suit);
}
}
}
public Card getCard(int suit, int rank) {
return cards[suit-1][rank-1];
}
}
Modified Deck.java:
import java.util.*;
public class Deck {
public static int numSuits = 4;
public static int numRanks = 13;
public static int numCards = numSuits * numRanks;
private Card[][] cards;
public Deck() {
cards = new Card[numSuits][numRanks];
for (Card.Suit suit : Card.Suit.values()) {
for (Card.Rank rank : Card.Rank.values()) {
// I dont know how to change this to work with Card.java
cards[suit-1][rank-1] = new Card(rank, suit);
}
}
}
public Card getCard(int suit, int rank) {
return cards[suit-1][rank-1];
}
}
and DisplayDeck.java
import java.util.*;
public class DisplayDeck {
public static void main(String[] args) {
Deck deck = new Deck();
/// how can i modify this code to work with both Card.java and Deck.java?
for (int suit = Card.DIAMONDS; suit <= Card.SPADES; suit++) {
for (int rank = Card.ACE; rank <= Card.KING; rank++) {
Card card = deck.getCard(suit, rank);
System.out.format("%s of %s%n",
card.rankToString(card.getRank()),
card.suitToString(card.getSuit()));
}
}
}
}
I update my code on what I got so far.
Get rid of all your int representations for rank and suit. You can replace loops like this:
for (int suit = Card.DIAMONDS; suit <= Card.SPADES; suit++) { ...
with an enhanced for loop:
for (Suit suit : Card.Suit.values()) { ...
Replace mappings from int to String with EnumMap<Suit,String> or EnumMap<Rank,String> as appropriate. Methods for checking whether an int value is valid can be disposed of, as a non-null enum is guaranteed to be a legal value.
EDIT (in response to comment): You can define your deck as simply an array of Card objects:
public class Deck {
private List<Card> cards;
public Deck() {
cards = new ArrayList<>();
for (Card.Suit suit : Card.Suit.values()) {
for (Card.Rank rank : Card.Rank.values()) {
cards.add(new Card(suit, rank));
}
}
}
}
With this, you can use the Collections utility class to trivially implement shuffling:
public class Deck {
. . . // as above
public void shuffle() {
Collections.shuffle(cards);
}
}
Since every enum type comes with a built-in compareTo() method that tells you the relative order of two enum values (of the same type). You can build on this to make the Card class implement Comparable<Card>. (This is left as an exercise for the reader :-)). Then you can trivially sort the deck back into its "brand new" order or even sort hands drawn randomly from the deck.
I see that you are currently retrieving a card by suit and rank. That's a weird way to access cards in a deck, especially since you just turn around and use the Card object to retrieve its suit and rank. But if you really need that kind of retrieval, you can expand the Deck definition to include internally an EnumMap<Suit, EnumMap<Rank, Card>> to allow you to quickly retrieve a card that way. (Yes, each card would then be stored in two distinct data structures inside the Deck object.) A better approach, in my view, is to add a method to retrieve a card by offset into the deck (and another method to tell you the deck size):
public class Deck {
. . .
public Card getCard(int index) {
return cards.get(index);
}
public int cardCount() {
return cards.size();
}
}
To be fancier, you can define a method that returns an iterator over all the cards:
public class Deck {
. . .
public Iterator<Card> iterator() {
return cards.iterator();
}
}
Even fancier yet, you could declare Deck to implement Iterable<Card>. Then you can print the deck contents very simply:
Deck deck = new Deck();
for (Card card : deck) {
// print the card
}
I have an error here and I don't know where it is coming from. I am in a beginner's java class is High School so I don't yet have much experience here. I have 3 programs that incorporate each other.
I have a card class that creates a playing card
//********************************************************************
// Card.java Author: Lewis and Loftus
//
// Solution to Programming Project 4.5
//********************************************************************
import java.util.*;
public class Card
{
public final static int ACE = 1;
public final static int TWO = 2;
public final static int THREE = 3;
public final static int FOUR = 4;
public final static int FIVE = 5;
public final static int SIX = 6;
public final static int SEVEN = 7;
public final static int EIGHT = 8;
public final static int NINE = 9;
public final static int TEN = 10;
public final static int JACK = 11;
public final static int QUEEN = 12;
public final static int KING = 13;
public final static int CLUBS = 1;
public final static int DIAMONDS = 2;
public final static int HEARTS = 3;
public final static int SPADES = 4;
private final static int NUM_FACES = 13;
private final static int NUM_SUITS = 4;
private int face, suit;
private String faceName, suitName;
private int myInt1, myInt2;
Random rand = new Random();
//-----------------------------------------------------------------
// Creates a random card.
//-----------------------------------------------------------------
public Card ()
{
face = rand.nextInt(4) + 1;
setFaceName();
suit = rand.nextInt(13) + 1;
setSuitName();
}
//-----------------------------------------------------------------
// Sets the string representation of the face using its stored
// numeric value.
//-----------------------------------------------------------------
private void setFaceName()
{
switch (face)
{
case 1:
faceName = "Ace";
break;
case 2:
faceName = "Two";
break;
case 3:
faceName = "Three";
break;
case 4:
faceName = "Four";
break;
case 5:
faceName = "Five";
break;
case 6:
faceName = "Six";
break;
case 7:
faceName = "Seven";
break;
case 8:
faceName = "Eight";
break;
case 9:
faceName = "Nine";
break;
case 10:
faceName = "Ten";
break;
case 11:
faceName = "Jack";
break;
case 12:
faceName = "Queen";
break;
case 13:
faceName = "King";
break;
}
}
//-----------------------------------------------------------------
// Sets the string representation of the suit using its stored
// numeric value.
//-----------------------------------------------------------------
private void setSuitName()
{
switch (suit)
{
case 1:
suitName = "Clubs";
break;
case 2:
suitName = "Diamonds";
break;
case 3:
suitName = "Hearts";
break;
case 4:
suitName = "Spades";
break;
}
}
//-----------------------------------------------------------------
// Determines if this card is higher than the passed card. The
// second parameter determines if aces should be considered high
// (beats a King) or low (lowest of all faces). Uses the suit
// if both cards have the same face.
//-----------------------------------------------------------------
public boolean isHigherThan (Card card2, boolean aceHigh)
{
boolean result = false;
if (face == card2.getFace())
{
if (suit > card2.getSuit())
result = true;
}
else
{
if (aceHigh && face == ACE)
result = true;
else
if (face > card2.getFace())
result = true;
}
return result;
}
//-----------------------------------------------------------------
// Determines if this card is higher than the passed card,
// assuming that aces should be considered high.
//-----------------------------------------------------------------
public boolean isHigherThan (Card card2)
{
return isHigherThan (card2, true);
}
//-----------------------------------------------------------------
// Returns the face (numeric value) of this card.
//-----------------------------------------------------------------
public int getFace ()
{
return face;
}
//-----------------------------------------------------------------
// Returns the suit (numeric value) of this card.
//-----------------------------------------------------------------
public int getSuit ()
{
return suit;
}
//-----------------------------------------------------------------
// Returns the face (string value) of this card.
//-----------------------------------------------------------------
public String getFaceName ()
{
return faceName;
}
//-----------------------------------------------------------------
// Returns the suit (string value) of this card.
//-----------------------------------------------------------------
public String getSuitName ()
{
return suitName;
}
//-----------------------------------------------------------------
// Returns the string representation of this card, including
// both face and suit.
//-----------------------------------------------------------------
public String toString ()
{
return faceName + " of " + suitName;
}
}
I have a Deck Of cards file that creates 52 cards
import java.util.*;
public class DeckOfCards
{
private Card deckOfCards[];
private int currentCardUsed;
private final int NumberOfCards = 52;
private int nextCard;
private Random rand;
String myString = "All Cards have been dealt.";
public DeckOfCards()
{
deckOfCards = new Card[NumberOfCards];
currentCardUsed = 0;
Random rand = new Random();
for(int index = 0; index < deckOfCards.length; index ++)
{
deckOfCards[index] = new Card();
}
}
public void shuffleCards()
{
currentCardUsed = 0;
for(int newCard = 0; newCard < deckOfCards.length; newCard ++)
{
int nextCard = rand.nextInt(NumberOfCards);
Card temporaryDeck = deckOfCards[newCard];
deckOfCards[newCard] = deckOfCards[nextCard];
deckOfCards[nextCard] = temporaryDeck;
}
}
public Card dealCard()
{
if(currentCardUsed < deckOfCards.length)
{
return deckOfCards[currentCardUsed ++];
}
else
{
return null;
}
}
}
And finally I have a driver class
public class DeckTester
{
public static void main(String [] args)
{
DeckOfCards deck = new DeckOfCards();
deck.shuffleCards();
System.out.println(deck.dealCard());
System.out.println(deck.dealCard());
System.out.println(deck.dealCard());
System.out.println(deck.dealCard());
System.out.println(deck.dealCard());
System.out.println(deck.dealCard());
}
}
None of them have errors. But when I run the driver I get this for the output
Exception in thread "main" java.lang.NullPointerException
at DeckOfCards.shuffleCards(DeckOfCards.java:39)
at DeckTester.main(DeckTester.java:8)
I have tried changing the Null in the deal Method to no avail.
It looks like you are declaring a local Random object in your constructor.
Try changing line 25 to be:
rand = new Random();
The line Random rand = new Random(); in your constructor creates a local object rand whose scope is limited to constructor only. You have two options to fix this issue :-
1) Change line in your constructor to
Random rand = new Random(); ---> this.rand = new Random()
2) Initialize your instance object at the time of declaration only. Change line
private Random rand; ---> private Random rand = new Random();
i seem to be having a problem with my deck class iterating through the Suits array.
Card class:
//David Diienno
//Lab 01
import java.util.Arrays;
public class Card {
private String m_rank; // card rank: a number between 2 and 10, or Jack, Queen, King or Ace
private char m_suit; // card suit: S, C, H, or D (spades, clubs, hearts, or diamonds)
// Helpful supporting structures
private static String [] Ranks = {"2","3","4","5","6","7","8","9","10", "Jack", "Queen", "King", "Ace"};
private static char [] Suits = {'C','H','D','S'};
// Default constructor: sets card rank to 2 and card suit to H
public Card(){
//setting default card to a 2 of hearts
m_rank = Ranks[0];
m_suit = Suits[1];
}
// Accessors and Mutators
public Card(String Rank, char suit){
if(isValidRank(Rank) == true){
m_rank = Rank;
}
if(isValidSuit(suit) == true){
m_suit = suit;
}
}
public String getRank() {
System.out.println(m_rank);
return m_rank;
}
public char getSuit() {
System.out.println(this.suitToString());
return m_suit;
}
public void setRank(String rank) {
// Make sure to validate provided input
if (isValidRank(rank) == true){
m_rank = rank;
}
else{
System.out.println("The rank you entered is invalid");
}
}
public void setSuit(char suit) {
// Make sure to validate provided input
if(isValidSuit(suit) == true){
m_suit = suit;
}
else{
System.out.println("The suit you entered is invalid");
}
}
// Method toString – returns string representation of the card that looks as follows:
// 2 of Hearts, 3 of Spades, Jack of Diamonds, etc.
// Requirement: you must use switch statement to convert character to string.
//
// Hint: card’s rank is already a string. Therefore you only need to convert card suit into
// a string that reads “Clubs”, “Spades”, “Hearts” or “Diamond s”
public String suitToString(){
switch(m_suit){
case 'c': return "Clubs";
case 'h': return "Hearts";
case 'd': return "Diamonds";
case 's': return "Spades";
default: return "Hearts";
}
}
public String toString() {
String data = "You have a " + m_rank + " of " + this.suitToString();
return data;
}
// Supporting static methods
// Returns an array of possible card ranks
public static String [ ] getPossibleRanks() {
//System.out.println(Arrays.toString(Ranks));
for(int i = 0; i < Card.Ranks.length; i ++){
System.out.println(Ranks[i]);
}
return Ranks;
}
// Returns an array of possible card suits
public static char [ ] getPossibleSuits() {
for(int i = 0; i < Card.Suits.length;i++){
System.out.println(Suits[i]);
}
return Suits;
}
public boolean isValidRank (String r){
for(int i = 0; i < Card.Ranks.length; i++ ){
if(Card.Ranks[i].equals( r)){
return true;
}
}
return false;
}
public boolean isValidSuit (char s){
for (int i = 0; i < Card.Suits.length; i++){
if(Card.Suits[i] == s){
return true ;
}
}
return false;
}
}
Deck class :
import java.util.*;
public class DeckOfCards extends Card {
private ArrayList <Card> deck;
private Card card;
private String [] Ranks = super.getPossibleRanks();
private char [] Suits = super.getPossibleSuits();
// public void resetDeckOfCards() {
public DeckOfCards()
deck = new ArrayList<Card>();
for(int s = 0; s < Suits.length; s++)
{
for(int r = 0; r < Ranks.length; r++){
card = new Card(Ranks[r],Suits[s]);
deck.add(card);
}
}
}
public void display(){
System.out.println(deck);
}
//public Card getCard() { /* ... */ }
//Remove a random card from the Array List of cards and return its value from this method Notes:
//1. Ensure that there is at least one card in the ArrayList of Cards
//2. If there are no more cards left in the ArrayList of Cards, reset the Deck of Cards
//3. Use class Random to create a random number which will be an index into ArrayList of Cards
//4. Remove and return card stored in the ArrayList of Cards in the randomly created index
// Return an ArrayList of specified size (i.e. returned cards are being removed from the deck). //
// Notes:
// 1. Use method getCard() to retrieve a single card
// 2. Validate the value of size passed into this method and return null if size is invalid
//public ArrayList<Card> getHand(int size) { /* ... */ }
}
Why when i display my array list it doesn't iterate through the suits but it does through the ranks, i still get 52 cards but all with same suit.
So the problem appears to be that your Suits array has capital letters, but your suitToString method is using a switch statement where lower case letters are used. Since the default case is Hearts, I bet all your cards are hearts.