diff --git a/10_Blackjack/java/src/Game.java b/10_Blackjack/java/src/Game.java
index e81c8f56..01e34d39 100644
--- a/10_Blackjack/java/src/Game.java
+++ b/10_Blackjack/java/src/Game.java
@@ -198,15 +198,28 @@ public class Game {
 	}
 
 	/**
-	 * Compares two hands accounting for natural blackjacks
+	 * Compares two hands accounting for natural blackjacks 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.
 	 */
-	private int compareHands(LinkedList<Card> handA, LinkedList<Card> handB) {
-		// TODO implement compareHands
-		return 0;
+	protected int compareHands(LinkedList<Card> handA, LinkedList<Card> handB) {
+		int scoreA = this.scoreHand(handA);
+		int scoreB = this.scoreHand(handB);
+
+		if(scoreA == 21 && scoreB == 21){
+			if(handA.size() == 2 && handB.size() != 2){
+				return 1; //Hand A wins
+			} else if (handA.size() != 2 && handB.size() == 2) {				
+				return -1; //Hand B wins
+			} else {
+				return 0; //Tie
+			}
+		} else {
+			return Integer.compare(scoreA, scoreB); 
+		}
 	}
 
 	/**
diff --git a/10_Blackjack/java/test/GameTest.java b/10_Blackjack/java/test/GameTest.java
index ad0d625b..00ced688 100644
--- a/10_Blackjack/java/test/GameTest.java
+++ b/10_Blackjack/java/test/GameTest.java
@@ -213,4 +213,113 @@ public class GameTest {
         // Then
         assertEquals(13, result);
     }
+
+    @Test
+    @DisplayName("compareHands should return 1 meaning A beat B, 20 to 12")
+    public void compareHandsAWins() {
+
+        givenStubGame();
+        LinkedList<Card> handA = new LinkedList<>();
+        handA.add(new Card(10, Card.Suit.SPADES));
+        handA.add(new Card(10, Card.Suit.CLUBS));
+
+        LinkedList<Card> handB = new LinkedList<>();
+        handB.add(new Card(1, Card.Suit.SPADES));
+        handB.add(new Card(1, Card.Suit.CLUBS));
+
+        int result = game.compareHands(handA,handB);
+
+        assertEquals(1, result);
+    }
+
+    @Test
+    @DisplayName("compareHands should return -1 meaning B beat A, 18 to 4")
+    public void compareHandsBwins() {
+        givenStubGame();
+        LinkedList<Card> handA = new LinkedList<>();
+        handA.add(new Card(2, Card.Suit.SPADES));
+        handA.add(new Card(2, Card.Suit.CLUBS));
+
+        LinkedList<Card> handB = new LinkedList<>();
+        handB.add(new Card(5, Card.Suit.SPADES));
+        handB.add(new Card(6, Card.Suit.HEARTS));
+        handB.add(new Card(7, Card.Suit.CLUBS));
+
+        int result = game.compareHands(handA,handB);
+
+        assertEquals(-1, result);
+    }
+
+    @Test
+    @DisplayName("compareHands should return 1 meaning A beat B, natural Blackjack to Blackjack")
+    public void compareHandsAWinsWithNaturalBlackJack() {
+        //Hand A wins with natural BlackJack, B with Blackjack
+        givenStubGame();
+        LinkedList<Card> handA = new LinkedList<>();
+        handA.add(new Card(10, Card.Suit.SPADES));
+        handA.add(new Card(1, Card.Suit.CLUBS));
+
+        LinkedList<Card> handB = new LinkedList<>();
+        handB.add(new Card(6, Card.Suit.SPADES));
+        handB.add(new Card(7, Card.Suit.HEARTS));
+        handB.add(new Card(8, Card.Suit.CLUBS));
+
+        int result = game.compareHands(handA,handB);
+
+        assertEquals(1, result);
+    }
+
+    @Test
+    @DisplayName("compareHands should return -1 meaning B beat A, natural Blackjack to Blackjack")
+    public void compareHandsBWinsWithNaturalBlackJack() {
+        givenStubGame();
+        LinkedList<Card> handA = new LinkedList<>();
+        handA.add(new Card(6, Card.Suit.SPADES));
+        handA.add(new Card(7, Card.Suit.HEARTS));
+        handA.add(new Card(8, Card.Suit.CLUBS));
+        
+        LinkedList<Card> handB = new LinkedList<>();
+        handB.add(new Card(10, Card.Suit.SPADES));
+        handB.add(new Card(1, Card.Suit.CLUBS));
+
+        int result = game.compareHands(handA,handB);
+
+        assertEquals(-1, result);
+    }
+
+    @Test
+    @DisplayName("compareHands should return 0, hand A and B tied with a Blackjack")
+    public void compareHandsTieBothBlackJack() {
+        givenStubGame();
+        LinkedList<Card> handA = new LinkedList<>();
+        handA.add(new Card(11, Card.Suit.SPADES));
+        handA.add(new Card(10, Card.Suit.CLUBS));
+        
+        LinkedList<Card> handB = new LinkedList<>();
+        handB.add(new Card(10, Card.Suit.SPADES));
+        handB.add(new Card(11, Card.Suit.CLUBS));
+
+        int result = game.compareHands(handA,handB);
+
+        assertEquals(0, result);
+    }
+
+    @Test
+    @DisplayName("compareHands should return 0, hand A and B tie without a Blackjack")
+    public void compareHandsTieNoBlackJack() {
+        givenStubGame();
+        LinkedList<Card> handA = new LinkedList<>();
+        handA.add(new Card(10, Card.Suit.DIAMONDS));
+        handA.add(new Card(10, Card.Suit.HEARTS));
+        
+        LinkedList<Card> handB = new LinkedList<>();
+        handB.add(new Card(10, Card.Suit.SPADES));
+        handB.add(new Card(10, Card.Suit.CLUBS));
+
+        int result = game.compareHands(handA,handB);
+
+        assertEquals(0, result);
+    }
+
+
 }
diff --git a/10_Blackjack/java/test/UserIoTest.java b/10_Blackjack/java/test/UserIoTest.java
index 2c27b609..a2fccc26 100644
--- a/10_Blackjack/java/test/UserIoTest.java
+++ b/10_Blackjack/java/test/UserIoTest.java
@@ -70,7 +70,7 @@ public class UserIoTest {
     @DisplayName("promptInt should print an error and reprompt if given a non-numeric response")
     public void testPromptIntRepromptsOnNonNumeric() {
         // Given
-        Reader in = new StringReader("foo\n1"); // word, then number
+        Reader in = new StringReader("foo" + System.lineSeparator() +"1"); // word, then number
         StringWriter out = new StringWriter();
         UserIo userIo = new UserIo(in, out);
 
@@ -78,7 +78,7 @@ public class UserIoTest {
         int result = userIo.promptInt("TEST");
 
         // Then
-        assertEquals("TEST? !NUMBER EXPECTED - RETRY INPUT LINE\n? ", out.toString());
+        assertEquals("TEST? !NUMBER EXPECTED - RETRY INPUT LINE" + System.lineSeparator() +"? ", out.toString());
         assertEquals(1, result);
     }
 }