some improvements from Jean-Francois

Author: davecom

CCSPiJ/src/chapter8/Board.java

@@ -28,7 +28,7 @@ public interface Board<Move> {
 	boolean isWin();
 
 	default boolean isDraw() {
-		return (!isWin() && (getLegalMoves().size() == 0));
+		return !isWin() && getLegalMoves().isEmpty();
 	}
 
 	double evaluate(Piece player);

CCSPiJ/src/chapter8/C4Piece.java

@@ -21,11 +21,12 @@ public enum C4Piece implements Piece {
 
 	@Override
 	public C4Piece opposite() {
-		if (this == C4Piece.B) {
+		switch (this) {
+		case B:
 			return C4Piece.R;
-		} else if (this == C4Piece.R) {
+		case R:
 			return C4Piece.B;
-		} else {
+		default: // E, empty
 			return C4Piece.E;
 		}
 	}

CCSPiJ/src/chapter8/TTTBoard.java

@@ -65,14 +65,14 @@ public List<Integer> getLegalMoves() {
 	@Override
 	public boolean isWin() {
 		// three row, three column, and then two diagonal checks
-		return position[0] == position[1] && position[0] == position[2] && position[0] != TTTPiece.E ||
-				position[3] == position[4] && position[3] == position[5] && position[3] != TTTPiece.E ||
-				position[6] == position[7] && position[6] == position[8] && position[6] != TTTPiece.E ||
-				position[0] == position[3] && position[0] == position[6] && position[0] != TTTPiece.E ||
-				position[1] == position[4] && position[1] == position[7] && position[1] != TTTPiece.E ||
-				position[2] == position[5] && position[2] == position[8] && position[2] != TTTPiece.E ||
-				position[0] == position[4] && position[0] == position[8] && position[0] != TTTPiece.E ||
-				position[2] == position[4] && position[2] == position[6] && position[2] != TTTPiece.E;
+		return checkPos(0, 1, 2) || checkPos(3, 4, 5) || checkPos(6, 7, 8)
+				|| checkPos(0, 3, 6) || checkPos(1, 4, 7) || checkPos(2, 5, 8)
+				|| checkPos(0, 4, 8) || checkPos(2, 4, 6);
+	}
+
+	private boolean checkPos(int p0, int p1, int p2) {
+		return position[p0] == position[p1] && position[p0] == position[p2]
+				&& position[p0] != TTTPiece.E;
 	}
 
 	@Override

CCSPiJ/src/chapter8/TTTPiece.java

@@ -21,11 +21,12 @@ public enum TTTPiece implements Piece {
 
 	@Override
 	public TTTPiece opposite() {
-		if (this == TTTPiece.X) {
+		switch (this) {
+		case X:
 			return TTTPiece.O;
-		} else if (this == TTTPiece.O) {
+		case O:
 			return TTTPiece.X;
-		} else {
+		default: // E, empty
 			return TTTPiece.E;
 		}
 	}