Exceptions and Files

src/main/java/Main.java

@@ -4,43 +4,59 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Scanner;
 
-public class Main {
+public class Main
+{
     static ArrayList<Product> productCatalog = new ArrayList<>();
-    public static void loadProducts() throws IOException{
+
+    public static void loadProducts() throws IOException
+    {
         InputStream input = Main.class
                 .getClassLoader()
                 .getResourceAsStream("products.csv");
-        if (input == null) {
+
+        if (input == null)
+        {
             throw new IOException("products.csv not found");
         }
-        Scanner scanner = new Scanner(input);
 
-        // TODO:
+        try (Scanner scanner = new Scanner(input))
-        // - Read each line from products.csv
+        {
-        // - For each line, parse productId, name, and price
+            while (scanner.hasNextLine())
-        // - The format of the file is like this:
+            {
-        //      [productId],[name],[price]
+                String line = scanner.nextLine();
-        // - Store Product objects in the productCatalog ArrayList
+                if (line.isBlank()) continue;
 
-        // NOTE
+                String[] parts = line.split(",");
-        // - The data in products.csv is guaranteed to be valid.
+
+                int id = Integer.parseInt(parts[0].trim());
+                String name = parts[1].trim();
+                double price = Double.parseDouble(parts[2].trim());
+
+                productCatalog.add(new Product(id, name, price));
+            }
+        }
     }
 
     public static void main(String[] args)
     {
-        try {
+        try
-            loadProducts();
+        {loadProducts();}
-        } catch (IOException e) {
+        catch (IOException e)
+        {
             System.err.println("Error reading products");
             System.out.println("Terminating the program...");
             return;
         }
+
         System.out.println("=== Products loaded");
 
-        ReportGenerator reportGenerator = new ReportGenerator("2025_order_details.csv", Collections.unmodifiableList(productCatalog));
+        ReportGenerator reportGenerator =
+                new ReportGenerator("2025_order_details.csv", Collections.unmodifiableList(productCatalog));
+
         reportGenerator.processFile();
         System.out.println("=== Order file processed");
+
         reportGenerator.saveReport();
         System.out.println("=== Report saved as report.txt");
     }
-}
+}

src/main/java/ReportGenerator.java

@@ -1,83 +1,82 @@
-import java.util.List;
+import java.io.*;
-
+import java.util.*;
-public class ReportGenerator {
 
+public class ReportGenerator
+{
     private final String ordersFilePath;
     private final List<Product> productList;
+    private double totalFinalCost = 0.0;
+    private int totalQuantity = 0;
+    private double totalDiscountValue = 0.0;
+    private int totalInvalidLines = 0;
 
-    private double totalFinalCost;
+    public ReportGenerator(String ordersFilePath, List<Product> productList)
-    private int totalQuantity;
+    {
-    private double totalDiscountValue;
-    private int totalInvalidLines;
-
-    public ReportGenerator(String ordersFilePath, List<Product> productList) {
         this.ordersFilePath = ordersFilePath;
         this.productList = productList;
     }
 
     public void processFile()
     {
-        // TODO:
+        Map<Integer, Product> productMap = new HashMap<>();
-        // 1. Open the order details CSV file
+        for (Product p : productList)
-        // 2. Read the file line by line
+        {
-        // 3. Split each line using comma delimiter
+            productMap.put(p.getProductID(), p);
-        //      (each line is guaranteed to contain exactly two commas)
+        }
-        // 4. Each line contains exactly 3 values in the format:
+
-        //      [productId],[quantity],[discountPercent]
+        try (BufferedReader reader = new BufferedReader(new FileReader(ordersFilePath)))
-        // 5. Attempt to convert values:
+        {
-        //      - productId -> int
+            String line;
-        //      - quantity -> int
+            while ((line = reader.readLine()) != null)
-        //      - discountPercent -> int
+            {
-        //    NOTE:
+                try
-        //      - quantity and discountPercent may contain invalid characters
+                {
-        //        (e.g., letters instead of numbers).
+                    String[] parts = line.split(",");
-        //      - If parsing any value fails (NumberFormatException),
+                    if (parts.length != 3) throw new Exception("Invalid format");
-        //        the entire line must be considered invalid.
+
-        //      - Use try-catch blocks and exception handling to safely
+                    int productId = Integer.parseInt(parts[0].trim());
-        //        handle parsing and validation errors without stopping
+                    int quantity = Integer.parseInt(parts[1].trim());
-        //        the processing of the remaining lines.
+                    int discountPercent = Integer.parseInt(parts[2].trim());
-        // 6. Validate parsed values:
+
-        //      - productId must be greater than 0
+                    Product product = productMap.get(productId);
-        //      - quantity must be greater than 0
+
-        //      - discountPercent must be between 0 and 99 inclusive
+                    if (productId <= 0 || quantity <= 0 || discountPercent < 0 || discountPercent > 99 || product == null)
-        // 7. Look for a Product in productList that matches productId
+                    {
-        // 8. If no Product with that ID exists in the catalog,
+                        throw new Exception("Validation failed");
-        //      the entire line is considered invalid
+                    }
-        // 9. If all values are valid and the product exists, calculate:
+
-        //      subtotal = quantity * product price
+                    double subtotal = quantity * product.getPrice();
-        //      discountValue = subtotal * discountPercent / 100
+                    double discountVal = subtotal * discountPercent / 100.0;
-        //      finalCost = subtotal - discountValue
+                    double finalCost = subtotal - discountVal;
-        // 10. Update report totals:
+
-        //      - totalQuantity += quantity
+                    totalQuantity += quantity;
-        //      - totalFinalCost += finalCost
+                    totalFinalCost += finalCost;
-        //      - totalDiscountValue += discountValue
+                    totalDiscountValue += discountVal;
-        // 11. If any parsing error, validation failure, or missing product occurs:
+
-        //      - increment totalInvalidLines
+                }
-        //      - skip the line and continue processing the next line
+                catch (Exception e) {totalInvalidLines++;}
-        // 12. Close all file resources
+            }
+        }
+        catch (IOException e)
+        {
+            System.err.println("Error reading file: " + e.getMessage());
+        }
     }
 
     public void saveReport()
     {
-        // TODO:
+        try (PrintWriter writer = new PrintWriter(new FileWriter("report.txt")))
-        // 1. Build a formatted report string
+        {
-        // 2. Include:
+            writer.println("========= SALES REPORT =========");
-        //      - total quantity
+            writer.println("Total Quantity Sold: " + totalQuantity);
-        //      - total final cost
+            writer.printf("Total Final Cost: $%.2f%n", totalFinalCost);
-        //      - total discount value
+            writer.printf("Total Discount Value: $%.2f%n", totalDiscountValue);
-        //      - total invalid lines
+            writer.println("Invalid Rows: " + totalInvalidLines);
-        // 3. Create/open output report file (name it report.txt)
+            writer.println("================================");
-        // 4. Write report string into file
+        }
-        // 5. Handle file writing exceptions
+        catch (IOException e)
-        // 6. Close writer resources
+        {
-
+            System.err.println("Error writing report: " + e.getMessage());
-        /* Example Structure
+        }
-        ========= SALES REPORT =========
-        Total Quantity Sold: 42
-        Total Final Cost: $1520.75
-        Total Discount Value: $230.50
-        Invalid Rows: 3
-        ================================
-        */
     }
 }