Android write csv

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class ArrayListDemo {
    public static void main(String[] args) throws IOException {
        List<String> list01;
        List<String> list02;
        List<String> list03;

        list01 = Arrays.asList("3D", "UX", "RAM", "CPU");
        list02 = Arrays.asList("200", "300", "400", "500");
        list03 = Arrays.asList("20", "30", "40", "50");

        ArrayList<List> total = new ArrayList<>();
        total.add(list01);
        total.add(list02);
        total.add(list03);
        writeFile(total, ",", System.getProperty("line.separator"));
    }

    private static void writeFile(ArrayList<List> arrayList, String separator, String newLine) throws IOException {
        BufferedWriter writer = new BufferedWriter(new FileWriter(new File("testResult.csv")));
        StringBuilder builder = new StringBuilder();
        for (List list : arrayList) {
            for (int i = 0; i < list.size(); i++) {
                if ( i != list.size() - 1) {
                    builder.append(String.valueOf(list.get(i))).append(separator);
                } else {
                    builder.append(list.get(i)).append(newLine);
                }
            }
        }

        writer.write(builder.toString());
        writer.flush();
        writer.close();
    }

}

$ cat TestResult.csv
3D,UX,RAM,CPU
200,300,400,500
20,30,40,50