Exporting a CSV file into arrays

Question

I have a CSV file with different columns of data.

Example:

100, 0.1, 0.5
200, 0.1, 0.1
300, 0.2, 0.5

etc

I want to store the first column into an array, the second column into its own array and so on so that I can use them for math equations.

import.java.util.Scanner; 
import java.io.File;

public class Example
{
    public static void main(String[] args) throws Exception 
    {
        Scanner s = new Scanner(new File("C://java//data.txt"));
    }
}

I'm pretty lost up until this point.

Use csvjdbc.sourceforge.net or something like it. What you are doing is the hard way. — matthudson
– matthudson, Commented Mar 5, 2014 at 0:52
So, what you're saying is that you have no idea what to do? Have you thought, in abstract terms, what it is that you want to implement? Why did you instantiate a Scanner - is there any functionality in that class you planned to use but are not telling us? You need to give us something more if you want help. — vanza
– vanza, Commented Mar 5, 2014 at 1:11
look up String.split() that would help you in what you need. The first split is 2 columns (hint split function have this capability), the second split is to again split the remaining data into array. good luck. — TA Nguyen
– TA Nguyen, Commented Mar 5, 2014 at 1:19
What I want to implement is a way to use this data from these columns and plug them into a mathematical equation such as the sum of column1*column3 or something like that. Thank you guys for your answers. I'm still a bit lost but I will try String.split(). — user3251256
– user3251256, Commented Mar 5, 2014 at 2:07
Explain a bit more what you mean by "column". Is a column all the rows, or 1 per row? That is, would you expect "100 200 300" to be a single column, or 3 different columns? — PNS
– PNS, Commented Mar 5, 2014 at 2:20

Sambhav · Accepted Answer · 2014-03-05 03:33:52Z

You can try this:

public class ReadCSV {
    public static List<List<Double>> getDimensionList(String key) throws Exception  
    {        
        List<List<Double>> listOfDimension = new ArrayList<List<Double>>();
        List<Double> dimensionList = null;      
        File file = null;
        BufferedReader br = null;
        try {
            file = new File(key);   
            br = new BufferedReader(new FileReader(file));

            String strLine = "";
            StringTokenizer dimensionVal = null;
            int lineNumber = 0, tokenNumber = 0;
            while( (strLine = br.readLine()) != null)
            {
                    dimensionVal = new StringTokenizer(strLine, ",");
                    dimensionList = new ArrayList<Double>();
                    while(dimensionVal.hasMoreTokens())
                    {
                        tokenNumber++;
                        dimensionList.add(Double.parseDouble(dimensionVal.nextToken()));

                        if(tokenNumber == 3)
                        {
                            Comparator<Double> comparator = Collections.reverseOrder();
                            Collections.sort(dimensionList,comparator);

                        }
                    }
                    listOfDimension.add(dimensionList);
                    tokenNumber = 0;
                lineNumber++;
            }
        }catch (Exception e) {
            throw new Exception();
        }
        finally
        {
            if(br != null)
                br.close();         
        }       
        return listOfDimension;
    }

    public static void main(String[] args) throws Exception {
        System.out.println(getDimensionList("dimension_details.csv"));
    }

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