how to put datas in a csv in java code example

Example 1: java read csv file into arraylist

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;

/**
 * Simple Java program to read CSV file in Java. In this program we will read
 * list of books stored in CSV file as comma separated values.
 * 
 * @author WINDOWS 8
 *
 */
public class CSVReaderInJava {

    public static void main(String... args) {
        List<Book> books = readBooksFromCSV("books.txt");

        // let's print all the person read from CSV file
        for (Book b : books) {
            System.out.println(b);
        }
    }

    private static List<Book> readBooksFromCSV(String fileName) {
        List<Book> books = new ArrayList<>();
        Path pathToFile = Paths.get(fileName);

        // create an instance of BufferedReader
        // using try with resource, Java 7 feature to close resources
        try (BufferedReader br = Files.newBufferedReader(pathToFile,
                StandardCharsets.US_ASCII)) {

            // read the first line from the text file
            String line = br.readLine();

            // loop until all lines are read
            while (line != null) {

                // use string.split to load a string array with the values from
                // each line of
                // the file, using a comma as the delimiter
                String[] attributes = line.split(",");

                Book book = createBook(attributes);

                // adding book into ArrayList
                books.add(book);

                // read next line before looping
                // if end of file reached, line would be null
                line = br.readLine();
            }

        } catch (IOException ioe) {
            ioe.printStackTrace();
        }

        return books;
    }

    private static Book createBook(String[] metadata) {
        String name = metadata[0];
        int price = Integer.parseInt(metadata[1]);
        String author = metadata[2];

        // create and return book of this metadata
        return new Book(name, price, author);
    }

}

class Book {
    private String name;
    private int price;
    private String author;

    public Book(String name, int price, String author) {
        this.name = name;
        this.price = price;
        this.author = author;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    @Override
    public String toString() {
        return "Book [name=" + name + ", price=" + price + ", author=" + author
                + "]";
    }

}

Output
Book [name=Effective Java, price=42, author=Joshua Bloch]
Book [name=Head First Java, price=39, author=Kathy Sierra]
Book [name=Head First Design Pattern, price=44, author=Kathy Sierra]
Book [name=Introduction to Algorithm, price=72, author=Thomas Cormen]

Example 2: csv file data structure java

List<List<String>> csv = new ArrayList<>();
//Generic answer