Requirement 4 is failing with following message: CodeGym security exception. You are performing a forbidden or potentially dangerous operation.

package com.codegym.task.task18.task1827;

/*
Prices

*/

import java.io.*;


public class Solution {
    public static void main(String[] args) throws IOException {
       BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
       String fileName = reader.readLine();;
        File file = new File(fileName);
        try {
            if(!file.exists()){
                throw new FileNotFoundException();
            }
        }catch (FileNotFoundException e){
            System.out.println("Product file does not exists: " + fileName);
        }

        if (args.length > 0 && args[0].equals("-c")){
            Product prod = new Product();
            prod.setProdName(args[1]);
            prod.setPrice(args[2]);
            prod.setQuantity(args[3]);
            if(file.exists()) {
                Product.refreshProdList(file, prod);
            }

        }
        else if(args.length == 0){

        }

    }
}

package com.codegym.task.task18.task1827;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class Product {

    private String prodId;
    private String prodName;
    private String price;
    private String quantity;

    public String getProdId() {
        return prodId;
    }

    public void setProdId(String prodId) {
        prodId = String.valueOf(Integer.parseInt(prodId) + 1);
        prodId = setPadding(8, prodId);
        this.prodId = prodId;
    }

    public String getProdName() {
        return prodName;
    }

    public void setProdName(String prodName) {
        prodName = setPadding(30, prodName);
        this.prodName = prodName;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        price = setPadding(8, price);
        this.price = price;
    }

    public String getQuantity() {
        return quantity;
    }

    public void setQuantity(String quantity) {
        quantity = setPadding(4, quantity);
        this.quantity = quantity;
    }


    public static void refreshProdList(File file, Product prod){
        List<String> prodList = new ArrayList<>();
        String record;

        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
            while ((record = reader.readLine()) != null){
                prodList.add(record);
            }
            reader.close();
            if(prodList.size() > 0){
                rewrite(file, prodList);
            }
            if(prod != null){
                setMaxId(prodList, prod);
                addProd2List(file, prod);
            }
        }catch (IOException e){
        }
    }

    private static void rewrite(File file, List<String> prodList) {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(file));
            for(String record : prodList){
                writer.write(record);
                writer.newLine();
            }
            writer.close();
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    private static void addProd2List(File file, Product prod){
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(file, true));
            String prodRecord = prod.getProdId() + prod.getProdName() + prod.getPrice() + prod.getQuantity();
            writer.write(prodRecord);
            writer.close();
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    private static void setMaxId(List<String> prodList, Product prod) {
        String maxId = "123456789";
        if (prodList.size() != 0) {
            maxId = "";
            String lastRecord = prodList.get(prodList.size() - 1);
            for(int i = 0;Character.isDigit(lastRecord.charAt(i)); i++){
                maxId += lastRecord.charAt(i);
            }
        }
        prod.setProdId(maxId);
    }

    private static String setPadding(int len, String field){
        int counter = field.length();
        while(counter < len) {
            field += " ";
            counter++;
        }
        if(counter > len){
            field = field.substring(0, len);
        }
        return field;
    }

}