mirror of
https://github.com/coding-horror/basic-computer-games.git
synced 2025-12-26 12:51:29 -08:00
cdf194f770
Java Records automatically acquire an implementation of equals and hashCode that accounts for their components. They also have read accessors for their components (card.suit() to get the suit).
62 lines
2.0 KiB
Java
62 lines
2.0 KiB
Java
import java.util.List;
|
|
|
|
public final class ScoringUtils {
|
|
|
|
/**
|
|
* Calculates the value of a hand. When the hand contains aces, it will
|
|
* count one of them as 11 if that does not result in a bust.
|
|
*
|
|
* @param hand the hand to evaluate
|
|
* @return The numeric value of a hand. A value over 21 indicates a bust.
|
|
*/
|
|
public static final int scoreHand(List<Card> hand) {
|
|
int nAces = (int) hand.stream().filter(c -> c.value() == 1).count();
|
|
int value = hand.stream()
|
|
.mapToInt(Card::value)
|
|
.filter(v -> v != 1) // start without aces
|
|
.map(v -> v > 10 ? 10 : v) // all face cards are worth 10. The 'expr ? a : b' syntax is called the
|
|
// 'ternary operator'
|
|
.sum();
|
|
value += nAces; // start by treating all aces as 1
|
|
if (nAces > 0 && value <= 11) {
|
|
value += 10; // We can use one of the aces to an 11
|
|
// You can never use more than one ace as 11, since that would be 22 and a bust.
|
|
}
|
|
return value;
|
|
}
|
|
|
|
/**
|
|
* Compares two hands accounting for natural blackjacks and busting using the
|
|
* java.lang.Comparable convention of returning positive or negative integers
|
|
*
|
|
* @param handA hand to compare
|
|
* @param handB other hand to compare
|
|
* @return a negative integer, zero, or a positive integer as handA is less
|
|
* than, equal to, or greater than handB.
|
|
*/
|
|
public static final int compareHands(List<Card> handA, List<Card> handB) {
|
|
int scoreA = scoreHand(handA);
|
|
int scoreB = scoreHand(handB);
|
|
if (scoreA == 21 && scoreB == 21) {
|
|
if (handA.size() == 2 && handB.size() != 2) {
|
|
return 1; // Hand A wins with a natural blackjack
|
|
} else if (handA.size() != 2 && handB.size() == 2) {
|
|
return -1; // Hand B wins with a natural blackjack
|
|
} else {
|
|
return 0; // Tie
|
|
}
|
|
} else if (scoreA > 21 || scoreB > 21) {
|
|
if (scoreA > 21 && scoreB > 21) {
|
|
return 0; // Tie, both bust
|
|
} else if (scoreB > 21) {
|
|
return 1; // A wins, B busted
|
|
} else {
|
|
return -1; // B wins, A busted
|
|
}
|
|
} else {
|
|
return Integer.compare(scoreA, scoreB);
|
|
}
|
|
}
|
|
|
|
}
|