Make Card immutable

10_Blackjack/java/src/Card.java

@@ -1,26 +1,34 @@
-public class Card {
+/**
+ * This is an example of an "immutable" class in Java. That's just a fancy way
+ * of saying the properties (value and suit) can't change after the object has
+ * been created (it has no 'setter' methods and the properties are 'final').
+ *
+ * Immutability often makes it easier to reason about code logic and avoid
+ * certain classes of bugs.
+ *
+ * Since it would never make sense for a card to change in the middle of a game,
+ * this is a good candidate for immutability.
+ *
+ */
+public final class Card {
 
 	public enum Suit {
 		HEARTS, DIAMONDS, SPADES, CLUBS;
 	}
 
-    private int value;
-    private Suit suit;
+    // Since this class is immutable, there's no reason these couldn't be
+    // 'public', but the pattern of using 'getters' is more consistent with
+    // typical Java coding patterns.
+	private final int value;
+	private final Suit suit;
 
-    public void setValue(int value) {
+	public Card(int value, Suit suit) {
 		this.value = value;
+		this.suit = suit;
 	}
 
 	public int getValue() {
 		return this.value;
     }
 
-    public void setSuit(Suit suit) {
-        this.suit = suit;
-    }
-
-    public Suit getSuit() {
-        return this.suit;
-    }
-
 }