EV $1\mathrm{.}0$ will read record data files $($multiple CSV files$)$ via Java file I$/$O$.$ The names of the data files will

be specified by the user using standard input. When EV $1\mathrm{.}0$ starts, it will enter a data input loop,

prompting the user for the name of a data file $($Enter data file name: $)$ and waiting for the user to

type a file name and hit enter. If the user enters the name of an available data file, EV $1\mathrm{.}0$ will open

the file using Java file I$/$O and read the data. If the user enters the name of a file that is not accessible, EV

$1\mathrm{.}0$ will report the error to the user $($File is not available.$)$ and continue in the loop, repeating the

prompt and waiting again for a file name. If the user hits enter without entering anything else, EV $1\mathrm{.}0$

will exit the data input loop. If no data has been read in when EV $1\mathrm{.}0$ exits the data input loop, EV

$1\mathrm{.}0$ will exit. Otherwise, EV $1\mathrm{.}0$ will move on to a data manipulation loop $($see below$).$

The data files will be organized as they were in the previous homework. However, for this homework,

the record$/$row data may be spread across multiple files. When EV reads in each file, it must make

sure the data in that file is internally consistent and alert the user to any errors encountered $($as described

in Homework $1).$ If a record appears in more than one data file, EV will retain the data

read most recently $($note the difference from the previous homework, although it will still reject

duplicates within the same file$).$ As each file is read in$,$ EV must update internal tallies of the total number

of EVRecord it attempted to read, the total number of valid record$/$rows read in$,$ and the total number

of EVRecord currently stored in memory. $($Note that these totals may be the same, but they may differ, as

some records may be duplicated.

After reading in and storing all the records from all the specified files, then you need to create RecordIDs,

Emission reduction and Petroleum reduction. After creating those columns for each valid record as

specified in Homework $3,$ EV will enter a data manipulation loop $($as mentioned above$).$ In this loop, EV

$1\mathrm{.}0$ will prompt the user with four options: $$o$$ for output, $$s$$ for sort, $$f$$ for find, $$e$$ for efficiency, and $$q$$

for quit $($Enter $($o$)$utput$,($s$)$ort$,($f$)$ind$,($e$)$fficiency$,$ or $($q$)$uit: $).$

If the user selects output, EV $1\mathrm{.}0$ will prompt the user for a filename $($Enter output file name: $)$ and read it

in from the console. If the user hits enter without specifying a filename, EV $1\mathrm{.}0$ will send the output to

standard out in the console. Otherwise, it will attempt to open the specified file for writing. If the user enters

the name of a file that is not accessible, EV $1\mathrm{.}0$ will report the error $($File is not available.$)$ and repeat the

prompt for the file name. If the file is accessible or the user has specified the standard out, EV $1\mathrm{.}0$ will print

out the records in whichever order it is presently ordered, followed by a row showing the internal tallies,

for example:

Data lines read: $5505$; Records in memory: $4217$; Invalid records: $750,$ Duplicate records: $538$

Other than this trailing row, EV $1\mathrm{.}0$ will exactly match the output format used by EV $0\mathrm{.}1$ through EV $0\mathrm{.}4.$

If the user selects sort, EV $1\mathrm{.}0$ will prompt the user for the data field to sort the record $($Enter sort attribute:

$).$ The user may enter a numeric value, which corresponds to the column order on which to sort. If the user

enters an invalid value for the column field on which to sort, EV $1\mathrm{.}0$ will return to the data manipulation

loop. If the user selects to sort by any valid column, EV $1\mathrm{.}0$ will sort the data based on those corresponding

values.

If the user selects find from the data manipulation loop, EV $1\mathrm{.}0$ will prompt the user for the data field on

which to search $($Enter search column: $).$ As with sort, the user may select a numeric value

corresponding to the column order on which to search. If the user selects any other invalid column, EV $1\mathrm{.}0$

will return to the data manipulation loop.

If the user chooses to find any other valid column, EV $1\mathrm{.}0$ will prompt the user for the value for search

$($Enter exact text on which to search for column value: $).$ If the user enters any text, EV $1\mathrm{.}0$ will search

for the given value but does not need to perform any validity check on the input data. If the user just hits

enter without giving a search string, EV $1\mathrm{.}0$ will return to the data manipulation loop.

If EV $1\mathrm{.}0$ finds one or more fields exactly matching a user request, EV $1\mathrm{.}0$ should display for the user $($by

sending to standard out in the console$)$ all the corresponding record in the same format as when printing the

data, but with a trailing row that indicates the number of records found in the format shown in the

following example:

Records found: $37.$

If no matching records are found, EV $1\mathrm{.}0$ should simply send to standard out the line indicating that the

number of records found is zero:

Records found: $0$