private int getNumPiecesInDiagonal(int startRow, int startCol, int endRow,
			int endCol) {
		int count = 0;
		// Check all positions on board and count only those that are on the
		// diagonal and not empty
		for (int rowCounter = 0; rowCounter < SIZE; rowCounter++) {
			for (int colCounter = 0; colCounter < SIZE; colCounter++) {
				// Position lies on the diagonal i.e. satisfies the line
				// equation
				// and position not empty
				if (Math.abs(endRow - rowCounter) == Math.abs(endCol
						- colCounter)
						&& Math.abs(rowCounter - startRow) == Math
								.abs(colCounter - startCol)
						&& !board[rowCounter][colCounter].isEmpty()) {
					count++;
				}
			}
		}
		return count;
	}