Question

(a) Create a Card class that represents a playing card. It should have an int instance variable named rank and a char variable named suit. Include the following methods:

• A constructor with two arguments for initializing the two instance variables.
• A copy constructor.
• A method equals — with one argument — which compares the calling object with another Card and returns true if and only if the corresponding ranks and suits are equal. Make sure your method will not generate null pointer exception.
• A method toString which returns the String value that represents the state of a Card object. For example, if rank is 2 and suit is ‘d’, The toString method should return (diamonds, 2).
• A static method read which reads rank and suit from the user, and returns an object of type Card.

(b) Write a driver program that creates four Card objects, where c1 is initialized to 2 and ‘d’, c2 is a copy of c1, c3 is initialized with user’s input, and c4 is set to null. Demonstrate all the capabilities and methods of the Card class and generate the following output.

~/cs1400/2020fall/exam $ java CardTest

card1 is (diamonds, 2)

card2 is (diamonds, 2)

creating card3...

enter rank(1-13): 8

enter suit(d=diamonds, h=hearts, s=spades, c=clubs): c

card3 is (clubs, 8)

set card4 to null

card1==card2? true

card1==card3? false

card1==card4? false

Answer 1

Program Code Screenshot (Card.java)

Program Code Screenshot (CardTest.java)

Program Sample Input/Output Screenshot

Program Code to Copy (Card.java)

import java.util.Scanner;

public class Card {
    // instance variables
    private int rank;
    private char suit;

    // getters and setters
    public int getRank() {
        return this.rank;
    }

    public void setRank(int rank) {
        this.rank = rank;
    }

    public char getSuit() {
        return this.suit;
    }

    public void setSuit(char suit) {
        this.suit = suit;
    }

    // constructor
    public Card(int r, char s) {
        rank = r;
        suit = s;
    }

    // copy constructor
    public Card(Card other) {
        rank = other.getRank();
        suit = other.getSuit();
    }

    // equals method
    public boolean equals(Card other) {
        if(other==null)
            return false;
        return rank == other.rank && suit == other.suit;
    }

    // toString method
    public String toString() {
        switch (suit) {
            case 'd':
                return "(diamonds, " + rank + ")";

            case 'h':
                return "(hearts, " + rank + ")";

            case 's':
                return "(spades, " + rank + ")";

            case 'c':
                return "(clubs, " + rank + ")";

        }
        return "";
    }

    // A static method read which reads rank and suit from the user, and returns an
    // object of type Card.
    public static Card create() {
        int rank;
        char suit;
        Scanner sc = new Scanner(System.in);

        System.out.print("enter rank(1-13): ");
        rank = sc.nextInt();

        System.out.print("enter suit(d=diamonds, h=hearts, s=spades, c=clubs): ");
        suit = sc.next().charAt(0);

        // create object and return
        return new Card(rank, suit);
    }
}

Program Code to Copy (CardTest.java)

public class CardTest {
    // Write a driver program that creates four Card objects
    public static void main(String[] args) throws Exception {
        // c1 is initialized to 2 and ‘d’
        Card c1 = new Card(2, 'd');

        // Print card 1
        System.out.println("card1 is "+c1);

        // c2 is a copy of c1
        Card c2 = new Card(c1);

        // Print card 2
        System.out.println("card2 is "+c2);

        // c3 is initialized with user’s input
        Card c3 = Card.create();

        // Print card 3
        System.out.println("card3 is "+c3);
        
        // c4 is set to null. 
        System.out.println("set card4 to null");
        Card c4 = null;


        // Demonstrate all the capabilities and methods of the Card class 
        System.out.println("card1==card2? "+c1.equals(c2));

        System.out.println("card1==card3? "+c1.equals(c3));

        System.out.println("card1==card4? "+c1.equals(c4));
        
    }
}