Add TODO Knight class, make Piece abstract

src/Board.java

@@ -40,11 +40,10 @@ public class Board {
         board = new Piece[BOARD_SIZE][BOARD_SIZE];
 
         // Initialize pieces
-        for (int y = 0; y < 2; y++)
-            for (int x = 0; x < BOARD_SIZE; x++) {
-                set(x, y, new Piece(true));
-                set(x, y + BOARD_SIZE - 2, new Piece(false));
-            }
+        set(1, 0, new Knight(true));
+        set(6, 0, new Knight(true));
+        set(1, 7, new Knight(false));
+        set(6, 7, new Knight(false));
     }
 
     public boolean outOfBounds(int x, int y) {

src/Knight.java

@@ -0,0 +1,14 @@
+import java.util.ArrayList;
+
+public class Knight extends Piece {
+    public Knight(boolean black) {
+        super(black);
+    }
+
+    @Override
+    public ArrayList<BoardCoordinate> getPossibleMoves(BoardCoordinate position) {
+        ArrayList<BoardCoordinate> possibleMoves = new ArrayList<>();
+        possibleMoves.add(new BoardCoordinate(position.x, position.y - 1)); // to up
+        return possibleMoves;
+    }
+}

src/Piece.java

@@ -1,7 +1,7 @@
 import java.awt.*;
 import java.util.ArrayList;
 
-public class Piece {
+public abstract class Piece {
     // Width and height of placeholder rectangle graphic
     public static final int DIMENSION = 32;
     public boolean black;
@@ -13,14 +13,7 @@ public class Piece {
         this.black = black;
     }
 
-    public ArrayList<BoardCoordinate> getPossibleMoves(BoardCoordinate position) {
-        ArrayList<BoardCoordinate> possibleMoves = new ArrayList<>();
-        possibleMoves.add(new BoardCoordinate(position.x - 1, position.y)); // to left
-        possibleMoves.add(new BoardCoordinate(position.x + 1, position.y)); // to right
-        possibleMoves.add(new BoardCoordinate(position.x, position.y - 1)); // to up
-        possibleMoves.add(new BoardCoordinate(position.x, position.y + 1)); // to down
-        return possibleMoves;
-    }
+    public abstract ArrayList<BoardCoordinate> getPossibleMoves(BoardCoordinate position);
 
     public ArrayList<BoardCoordinate> getLegalMoves(BoardCoordinate position, Board board) {
         ArrayList<BoardCoordinate> legalMoves = getPossibleMoves(position);