Exceptions and Files
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+32
-16
@@ -4,42 +4,58 @@ import java.util.ArrayList;
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import java.util.Collections;
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import java.util.Scanner;
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public class Main {
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public class Main
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{
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static ArrayList<Product> productCatalog = new ArrayList<>();
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public static void loadProducts() throws IOException{
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public static void loadProducts() throws IOException
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{
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InputStream input = Main.class
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.getClassLoader()
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.getResourceAsStream("products.csv");
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if (input == null) {
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if (input == null)
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{
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throw new IOException("products.csv not found");
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}
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Scanner scanner = new Scanner(input);
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// TODO:
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// - Read each line from products.csv
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// - For each line, parse productId, name, and price
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// - The format of the file is like this:
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// [productId],[name],[price]
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// - Store Product objects in the productCatalog ArrayList
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try (Scanner scanner = new Scanner(input))
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{
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while (scanner.hasNextLine())
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{
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String line = scanner.nextLine();
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if (line.isBlank()) continue;
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// NOTE
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// - The data in products.csv is guaranteed to be valid.
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String[] parts = line.split(",");
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int id = Integer.parseInt(parts[0].trim());
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String name = parts[1].trim();
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double price = Double.parseDouble(parts[2].trim());
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productCatalog.add(new Product(id, name, price));
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}
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}
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}
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public static void main(String[] args)
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{
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try {
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loadProducts();
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} catch (IOException e) {
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try
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{loadProducts();}
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catch (IOException e)
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{
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System.err.println("Error reading products");
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System.out.println("Terminating the program...");
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return;
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}
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System.out.println("=== Products loaded");
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ReportGenerator reportGenerator = new ReportGenerator("2025_order_details.csv", Collections.unmodifiableList(productCatalog));
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ReportGenerator reportGenerator =
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new ReportGenerator("2025_order_details.csv", Collections.unmodifiableList(productCatalog));
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reportGenerator.processFile();
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System.out.println("=== Order file processed");
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reportGenerator.saveReport();
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System.out.println("=== Report saved as report.txt");
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}
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@@ -1,83 +1,82 @@
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import java.util.List;
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public class ReportGenerator {
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import java.io.*;
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import java.util.*;
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public class ReportGenerator
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{
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private final String ordersFilePath;
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private final List<Product> productList;
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private double totalFinalCost = 0.0;
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private int totalQuantity = 0;
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private double totalDiscountValue = 0.0;
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private int totalInvalidLines = 0;
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private double totalFinalCost;
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private int totalQuantity;
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private double totalDiscountValue;
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private int totalInvalidLines;
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public ReportGenerator(String ordersFilePath, List<Product> productList) {
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public ReportGenerator(String ordersFilePath, List<Product> productList)
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{
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this.ordersFilePath = ordersFilePath;
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this.productList = productList;
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}
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public void processFile()
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{
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// TODO:
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// 1. Open the order details CSV file
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// 2. Read the file line by line
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// 3. Split each line using comma delimiter
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// (each line is guaranteed to contain exactly two commas)
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// 4. Each line contains exactly 3 values in the format:
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// [productId],[quantity],[discountPercent]
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// 5. Attempt to convert values:
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// - productId -> int
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// - quantity -> int
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// - discountPercent -> int
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// NOTE:
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// - quantity and discountPercent may contain invalid characters
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// (e.g., letters instead of numbers).
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// - If parsing any value fails (NumberFormatException),
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// the entire line must be considered invalid.
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// - Use try-catch blocks and exception handling to safely
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// handle parsing and validation errors without stopping
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// the processing of the remaining lines.
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// 6. Validate parsed values:
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// - productId must be greater than 0
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// - quantity must be greater than 0
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// - discountPercent must be between 0 and 99 inclusive
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// 7. Look for a Product in productList that matches productId
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// 8. If no Product with that ID exists in the catalog,
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// the entire line is considered invalid
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// 9. If all values are valid and the product exists, calculate:
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// subtotal = quantity * product price
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// discountValue = subtotal * discountPercent / 100
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// finalCost = subtotal - discountValue
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// 10. Update report totals:
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// - totalQuantity += quantity
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// - totalFinalCost += finalCost
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// - totalDiscountValue += discountValue
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// 11. If any parsing error, validation failure, or missing product occurs:
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// - increment totalInvalidLines
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// - skip the line and continue processing the next line
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// 12. Close all file resources
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Map<Integer, Product> productMap = new HashMap<>();
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for (Product p : productList)
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{
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productMap.put(p.getProductID(), p);
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}
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try (BufferedReader reader = new BufferedReader(new FileReader(ordersFilePath)))
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{
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String line;
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while ((line = reader.readLine()) != null)
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{
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try
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{
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String[] parts = line.split(",");
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if (parts.length != 3) throw new Exception("Invalid format");
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int productId = Integer.parseInt(parts[0].trim());
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int quantity = Integer.parseInt(parts[1].trim());
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int discountPercent = Integer.parseInt(parts[2].trim());
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Product product = productMap.get(productId);
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if (productId <= 0 || quantity <= 0 || discountPercent < 0 || discountPercent > 99 || product == null)
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{
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throw new Exception("Validation failed");
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}
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double subtotal = quantity * product.getPrice();
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double discountVal = subtotal * discountPercent / 100.0;
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double finalCost = subtotal - discountVal;
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totalQuantity += quantity;
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totalFinalCost += finalCost;
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totalDiscountValue += discountVal;
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}
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catch (Exception e) {totalInvalidLines++;}
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}
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}
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catch (IOException e)
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{
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System.err.println("Error reading file: " + e.getMessage());
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}
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}
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public void saveReport()
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{
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// TODO:
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// 1. Build a formatted report string
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// 2. Include:
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// - total quantity
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// - total final cost
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// - total discount value
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// - total invalid lines
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// 3. Create/open output report file (name it report.txt)
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// 4. Write report string into file
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// 5. Handle file writing exceptions
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// 6. Close writer resources
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/* Example Structure
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========= SALES REPORT =========
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Total Quantity Sold: 42
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Total Final Cost: $1520.75
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Total Discount Value: $230.50
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Invalid Rows: 3
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================================
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*/
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try (PrintWriter writer = new PrintWriter(new FileWriter("report.txt")))
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{
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writer.println("========= SALES REPORT =========");
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writer.println("Total Quantity Sold: " + totalQuantity);
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writer.printf("Total Final Cost: $%.2f%n", totalFinalCost);
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writer.printf("Total Discount Value: $%.2f%n", totalDiscountValue);
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writer.println("Invalid Rows: " + totalInvalidLines);
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writer.println("================================");
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}
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catch (IOException e)
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{
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System.err.println("Error writing report: " + e.getMessage());
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}
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}
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}
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