Reading CSV files safely
You're ready to read a CSV file of coffee sales. Use data validation functions to read in the data and validate the data types.
This exercise is part of the course
Cleaning Data in Java
Exercise instructions
- Parse the format of the date string as
M/d/yy
. - Read the sales
quantity
as anInteger
.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
import java.io.*;
import java.time.*;
import java.time.format.*;
import java.util.*;
import org.apache.commons.lang3.math.NumberUtils;
public class CoffeeSalesExample {
private record CoffeeSales(LocalDate date, String coffeeName, String paymentMethod, Integer quantity, Double amount) {}
private static LocalDate parseDate(String dateStr) {
// Parse the format of the date string
return ____.____(dateStr, DateTimeFormatter.ofPattern("M/d/yy"));
}
private static String validateNumeric(String value) {
if (NumberUtils.isParsable(value)) return value;
throw new IllegalArgumentException("Invalid: " + value);
}
public static double parsePrice(String priceText) {
if (NumberUtils.isParsable(priceText.replace("$", ""))) {
return Double.parseDouble(priceText.replace("$", ""));
}
throw new IllegalArgumentException("Invalid price: " + priceText);
}
public static CoffeeSales parseSalesData(String[] fields) {
LocalDate publishDate = parseDate(fields[0]);
String coffeeName = fields[1];
String paymentMethod = fields[2];
// Read quantity as an Integer
Integer quantity = ____.____(validateNumeric(fields[3]));
Double amount = parsePrice(fields[4]);
return new CoffeeSales(publishDate, coffeeName, paymentMethod, quantity, amount);
}
public static void main(String[] args) throws IOException, InterruptedException {
List sales = new ArrayList<>();
String filename = "coffee.csv";
try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
String line = reader.readLine();
while ((line = reader.readLine()) != null) {
String[] fields = line.split(",");
sales.add(parseSalesData(fields));
}
}
sales.forEach(System.out::println);
}
}