从csv文件中提取数据并放入2D数组 - 重构

Question

I need read data from csv file and much more convinience for me is put there to 2D array (to my mind it's easiest way to work with this "schedule" data). Each file line contained information in following format:

Instructor, Course, Group, Student, Result

as follows example:

Paul Schwartz,Introduction to Computer Architecture,I1,Ben Dunkin,88
Muhamed Olji,Object Oriented Programming,I4,Mike Brown,73

But my code needs some simplify. But I don't know how to make it easier and ask of You .

Code:

private String[][] fileContent(String pathToCSVFile) {
    final int ROWS = 100;
    final int COLUMNS = 5;
    String fileData[][] = new String[ROWS][COLUMNS];
    Scanner scanner = new Scanner(pathToCSVFile);
    boolean done = false;
    int i, j;

    while (!done) {
        for (i = 0; i >= 0; i++) {
           for (j = 0; j >= 0; j++) {
               String str[] = scanner.nextLine().split(","); 
               for (int element = 0; element < str.length; element++) {
                   fileData[i][element] = str[element];
                   if (i >= ROWS) {
                       Arrays.copyOf(fileData, fileData.length * 2);
                   }
               }                   
           }
        }

        if (!scanner.hasNextLine()) done = true;
    }

    return  fileData;
}

• How to refactor this snippet of code for better simplicity?
• Does exist any better way for partially filled array (than Arrays.copyOf(fileData, fileData.length * 2) )?

Answer 1

Using openCSV, you can get a list containing all the lines and convert it to an array (or just keep the list):

try (CSVReader reader = new CSVReader(new BufferedReader(
          new FileReader(pathToCSVFile)));) {

    List<String[]> lines = reader.readAll();
    return lines.toArray(new String[lines.size()][]);
}

(using Java 7 try-with-resources syntax)

Answer 2

First of all, be careful with those for loops. They are "almost" undefined loops, because they start with i,j=0, and loop while >=0 (always, until they overflow into a negative number). And why do you need them anyway? I think with you while and the for(element) you are done, right? Something like that (I didn't tried, is just to explain the concept)

private String[][] fileContent(String pathToCSVFile) {
    final int ROWS = 100;
    final int COLUMNS = 5;
    String fileData[][] = new String[ROWS][COLUMNS];
    Scanner scanner = new Scanner(pathToCSVFile);
    boolean done = false;
    int i=0;

    while (!done) {
        String str[] = scanner.nextLine().split(","); 
        for (int element = 0; element < str.length; element++) {
            fileData[i][element] = str[element];
            if (i >= ROWS) {
                Arrays.copyOf(fileData, fileData.length * 2);
            }
        }
        if (!scanner.hasNextLine())
            done = true;
        else
            i++;
    }
    return  fileData;
}

By the way, why don't you use objects, like an ArrayList? It would make your life easier, so you don't have to worry about memory handling. You just add new objects.

Something like an ArrayList <ArrayList <String>>