import java.util.Arrays;

public class Card {

public static final String[] VALID_RANKS =

{"2", "3", "4", "5", "6", "7", "8", "9",

"10", "jack", "queen", "king", "ace"};

public static final String[] VALID_SUITS =

{"diamonds", "clubs", "hearts","spades"};

private String rank;

private String suit;

public Card(String aRank, String aSuit) {

String theRank = normalizeString(aRank);

String theSuit = normalizeString(aSuit);

if (isValidRank(theRank)) {

rank = theRank;

} else {

String msg = "Illegal rank: " + theRank;

throw new IllegalArgumentException(msg);

}

if (isValidSuit(theSuit)) {

suit = theSuit;

} else {

String msg = "Illegal suit: " + theSuit;

throw new IllegalArgumentException(msg);

}

}

private static String normalizeString(String someString) {

return someString.trim().toLowerCase();

}

private static boolean isValidRank(String someRank) {

return Arrays.asList(VALID_RANKS).contains(someRank);

}

private static boolean isValidSuit(String someSuit) {

return Arrays.asList(VALID_SUITS).contains(someSuit);

}

public String toString() {

return rank + " of " + suit;

}

public boolean equals(Object other) {

if (other == null) return false;

if (this == other) return true;

if (!(other instanceof Card)) return false;

Card that = (Card) other;

return this.rank.equals(that.rank) && this.suit.equals(that.suit);

}

public static void main(String[] args) {

Card c1 = new Card("ace", "spades");

Card c2 = new Card("ace", "spades");

Card c3 = c1;

System.out.println("c1 == c2 returns " + (c1 == c2));

System.out.println("c1.equals(c2) returns " + c1.equals(c2));

System.out.println("c1 == c3 returns " + (c1 == c3));

System.out.println("c1.equals(c3) returns " + c1.equals(c3));

String a = "foo";

String b = "foo";

System.out.println(a == b);

}

}