Using I/O stream to parse CSV file

Question

I have a CSV file of US population data for every county in the US. I need to get each population from the 8th column of the file. I'm using a fileReader() and bufferedStream() and not sure how to use the split method to accomplish this. I know this isn't much information but I know that I'll be using my args[0] as the destination in my class.

I'm at a loss to where to being to be honest.

import java.io.FileReader;

public class Main {

    public static void main(String[] args) {
      BufferedReader() buff = new BufferedReader(new FileReader(args[0]));
      String 
    }
    try {

    }
}

The output should be an integer of the total US population. Any help with pointing me in the right direction would be great.

What you are trying to do here is to reimplement a csv parser. By experience i can tell you that its a painful road. You would have to deal with escaping quotes, escaping commas, dealing with charsets etc. Instead try using super-csv.github.io/super-csv/index.html or some other similar library. These libs are tried and tested and speed up your dev time. Here's some sample code : super-csv.github.io/super-csv/examples_reading.html . — Arpan Kanthal
– Arpan Kanthal, Commented Aug 5, 2019 at 21:44
This has been asked a million times before. stackoverflow.com/a/844185/1044799 — awm
– awm, Commented Aug 5, 2019 at 21:47
Assuming you have copied your "attempt" correctly, you cannot have a try outside of a method. Try needs to surround a block of code that might "throw" an error (Exception). Thus it needs to be inside (not outside) your main method. — GMc
– GMc, Commented Aug 5, 2019 at 21:55
Also, I completely agree about using a library for parsing CSV, but I am guessing your homework assignment is to use split. Did you try searching for "how to split a string on a character in java"? If so, try working that into your assignment and when you get stuck, ask a follow up question. Alternatively, if you are free to choose your own method to process the csv file, follow the excellent advice here and use a library. Again, when you get stuck with the library approach, ask a follow up question. — GMc
– GMc, Commented Aug 5, 2019 at 21:58

madhead · Accepted Answer · 2019-08-05 21:56:10Z

Don't reinvent the wheel, don't parse CSV yourself: use a library. Even such a simple format as CSV has nuances: fields can be escaped with quotes or unescaped, the file can have or have not a header and so on. Besides that you have to test and maintain the code you've wrote. So writing less code and reusing libraries is good.

There are a plenty of libraries for CSV in Java:

IMHO, the first two are the most popular.

Here is an example for Apache Commons CSV:

final Reader in = new FileReader("counties.csv");
final Iterable<CSVRecord> records = CSVFormat.DEFAULT.parse(in);

for (final CSVRecord record : records) { // Simply iterate over the records via foreach loop. All the parsing is handler for you
    String populationString = record.get(7); // Indexes are zero-based
    String populationString = record.get("population"); // Or, if your file has headers, you can just use them

    … // Do whatever you want with the population
}

Look how easy it is! And it will be similar with other parsers.

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