Splitting a csv file with quotes as text-delimiter using String.split()

Question

I have a comma separated file with many lines similar to one below.

Sachin,,M,\"Maths,Science,English\",Need to improve in these subjects.

Answer 1

As your problem/requirements are not all that complex a custom method can be utilized that performs over 20 times faster and produces the same results. This is variable based on the data size and number of rows parsed, and for more complicated problems using regular expressions is a must.

import java.util.Arrays;
import java.util.ArrayList;
public class SplitTest {

public static void main(String[] args) {

    String s = "Sachin,,M,\"Maths,Science,English\",Need to improve in these subjects.";
    String[] splitted = null;

 //Measure Regular Expression
    long startTime = System.nanoTime();
    for(int i=0; i<10; i++)
    splitted = s.split(",(?=([^\"]*\"[^\"]*\")*[^\"]*$)");
    long endTime =   System.nanoTime();

    System.out.println("Took: " + (endTime-startTime));
    System.out.println(Arrays.toString(splitted));
    System.out.println("");


    ArrayList sw = null;        
 //Measure Custom Method
            startTime = System.nanoTime();
    for(int i=0; i<10; i++)
    sw = customSplitSpecific(s);
    endTime =   System.nanoTime();

    System.out.println("Took: " + (endTime-startTime));
    System.out.println(sw);         
}

public static ArrayList customSplitSpecific(String s)
{
    ArrayList words = new ArrayList();
    boolean notInsideComma = true;
    int start =0, end=0;
    for(int i=0; i

}

On my own computer this produces:

Took: 6651100
[Sachin, , M, "Maths,Science,English", Need to improve in these subjects.]

Took: 224179
[Sachin, , M, "Maths,Science,English", Need to improve in these subjects.]