Reading and processing a file line by line

Files containing data in the comma separated values (csv) format are structured so that one line contains data about one object, so we need a way to read and process the file line by line. As an example, we use the data file winequality-red.csv, that contains 1,599 sample measurements, 12 data columns, such as pH and alcohol, per sample, separated by a semicolon (;), of which you can see the top 20 in the following screenshot:

How to do it...

Examine the code of the command-line project processing_lines using the following methods:

1. Using the readAsLines method as shown in the following code:

   import 'dart:io';
   // for step 3:
   import 'dart:async';
   import 'dart:convert';
   
   main() {
     File data= new File("../winequality-red.csv");
     data.readAsLines().then(processLines)
     .catchError((e) => handleError(e));
   }
   
   processLines(List<String> lines) {
     // process lines:
     for (var line in lines) {
     print(line);
     }
   }
   
   handleError(e) {
     print("An error...