Validator complaints unclear, especially "Server security exception. You are performing a forbidden or potentially dangerous operation."

Frage zur Aufgabe

In der Diskussion

My program works just fine. But the validator complains: - Wenn das Programm mit den Parametern „-c productName price quantity“ ausgeführt wird, muss am Ende der Datei eine neue Zeile mit dem entsprechenden Produkt hinzugefügt werden. -- Mentor: Server security exception. You are performing a forbidden or potentially dangerous operation. => What kind of security exception? Maybe because of raw string processing instead of using a Reader/Writer? - Das Produkt muss die nächste ID nach der größten ID erhalten, die in der Datei gefunden wurde. => The program does this. - Das Format der neuen Produktlinie muss genau dem in der Aufgabe angegebenen Format entsprechen. => Seems to be correct format. - Die Dateidatenströme müssen geschlossen werden. -- Mentor: Der Dateieingabedatenstrom wurde nicht geschlossen. => Using try-with-resource...

CrUD für eine Tabelle in einer Datei.
Lies einen Dateinamen für CrUD-Operationen von der Konsole.

Das Programm wird mit den folgenden Parametern gestartet:
-c productName price quantity

Parameterwerte:
id besteht aus 8 Zeichen.
productName besteht aus 30 Zeichen.
price besteht aus 8 Zeichen.
quantity besteht aus 4 Zeichen.
-c fügt das Produkt mit den angegebenen Parametern am Ende der Datei hinzu und erzeugt eine id durch Inkrementieren der größten in der Datei gefundenen id.

Die Dateidaten werden in der folgenden Reihenfolge (ohne trennende Leerzeichen) gespeichert:
id productName price quantity

Jedes Datenfeld wird bis zu seiner vorgegebenen Länge mit Leerzeichen aufgefüllt.

Bevor du eine neue Zeile hinzufügst, schreibe den gesamten Inhalt der Datei neu.

Beispiel:
19847 Swim trunks, blue 159.00 12 198479 Swim trunks, black with printe173.00 17 19847983Snowboard jacket with reflecti10173.991234

Anforderungen:

Das Programm muss einen Dateinamen für CrUD-Operationen von der Konsole lesen.
Die Solution-Klasse darf keine statischen Variablen verwenden.
Wenn du das Programm ohne Parameter ausführst, muss die product-Liste unverändert bleiben.
Wenn das Programm mit den Parametern „-c productName price quantity“ ausgeführt wird, muss am Ende der Datei eine neue Zeile mit dem entsprechenden Produkt hinzugefügt werden.
Das Produkt muss die nächste ID nach der größten ID erhalten, die in der Datei gefunden wurde.
Das Format der neuen Produktlinie muss genau dem in der Aufgabe angegebenen Format entsprechen.
Die Dateidatenströme müssen geschlossen werden.

package de.codegym.task.task18.task1827; /* Preise */ import java.io.BufferedReader; import java.io.InputStreamReader; public class Solution { public static void main(String[] args) throws Exception { if (args.length == 0) return; BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String filename = reader.readLine(); ProductList productList = new ProductList(); productList.loadFromFile(filename); if ("-c".equals(args[0])) { String productName = args[1]; if (productName.length() > 30) productName = productName.substring(0, 30); String priceString = args[2]; if (priceString.length() > 8) priceString = priceString.substring(0, 8); double price = Double.parseDouble(args[2]); String quantityString = args[3]; if (quantityString.length() > 4) quantityString = quantityString.substring(0, 4); int quantity = Integer.parseInt(quantityString); productList.addProduct(productName, price, quantity); productList.writeToFile(filename); } } }

Kommentare (7)

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Marco Heyde Teamlead

17 August 2023, 11:08

Thanks for suggestions. > parsing a String to a number with leading or trailing spaces Changed by adding trim(), but no change in validation result, e.g.: long id = Long.parseLong(line.substring(0, 0 + 8).trim()) > using Locale.US This is done to force String.format to use "." instead of "," for floating point representation. Default locale is German on my local machine. Assuming the server has default locale "US" on server side I tested without explicit definition of Locale.US. No change in validation result. Still "Server security exception" Locale only get's in contact with SecurityManager if one tries to set a new default locale - what I won't do in this code. Stream-Api usage should never cause security manger issues. I've used my code from this task1827 also in task1828 with necessary enhancements for update/delete operations. In task1828 everything validates just fine. So seems the validators in task1827 are simply broken.

Guadalupe Gagnon

Level 37 , Tampa, United States

17 August 2023, 13:57

I messaged you

Guadalupe Gagnon

Level 37 , Tampa, United States

17 August 2023, 16:43

another suggestion to try: put your classes in the Solution class as static classes:

public class Solution {
   static class Product { }
   static class ProductList { }

   main() { }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

16 August 2023, 19:43

One problem that I see is that parsing a String to a number with leading or trailing spaces will result in an exception. This is most likely happening on lines 29 and 34 of your main class. Try fixing that and see what happens. Another thing is I don't think you should be using Locale.US, this may be causing your security warning. In my opinion your code could be greatly simplified by not breaking apart the file into your Product and ProductList classes. You need nothing from the data in the file other than the ID numbers. Also the task is dealing with Strings so other than having to get the max ID there is no reason to convert to numbers. Here is how I would approach it: step 1) read the whole file into a String, so the String would be: "19847 Swim trunks, blue 159.00 12 198479 Swim trunks, black with printe173.00 17 19847983Snowboard jacket with reflecti10173.991234 19847984product1 100.00 100 " step 2, 3, and 4) read the first 8 digits of each line, parse to each to int, figure out the max 5) start a string for the new product with the new ID needed from figuring out the max in that last step 6) continue building that string from the rest of the args 7) write the (whole) file data back to the file. 8) add a line break and write the new product to the file. Adding more steps than is necessary just increases the chance of accidently programming in bugs.

Thomas

Level 41 , Bayreuth, Germany

16 August 2023, 19:59

In addition to what Lupe said: 1. you did not close the BufferedReader object. Maybe that will fix the not closed data streams. 2. I remember a student who wasn't able to validate due to parsing the price to a double. When changing that to a String it worked. I think CG may test with different formats like 3.0, 3, and 3.00 or something like that. And you won't be able to keep these different formats when changing the raw data to double.

Guadalupe Gagnon

Level 37 , Tampa, United States

16 August 2023, 20:10

Maybe using the stream api is causing the security warning?

Thomas

Level 41 , Bayreuth, Germany

16 August 2023, 20:43

Usually CG does not complain about using the stream api. Don't know for sure how it is for this task. At least it is not really necessary. CG uses well ordered test data. So just reading all into a list, grabbing the last entry and parsing its first 8 chars to an int will work perfectly. But of course you can streamify that, too :)

private static int getLastProductId(List<String> products) {
    return Integer.parseInt(products.get(products.size() - 1).substring(0, 8).trim());
}

private static List<String> readProducts(String fileName) throws IOException {
    try (Stream<String> in = new BufferedReader(new FileReader(fileName)).lines()) {
        return in.collect(Collectors.toList());
    }
}