I fixed the main part and part of the report.

src/main/java/Main.java

@@ -14,6 +14,53 @@ public class Main {
             throw new IOException("products.csv not found");
         }
         Scanner scanner = new Scanner(input);
+        while (scanner.hasNextLine())
+        {
+            String ln = scanner.nextLine() ;
+            int part_number = 0 ;
+            String part  = "";
+            String product_id = "" ;
+            String product_name = "" ;
+            String product_price = "" ;
+            for (char x : ln.toCharArray() )
+            {
+
+                  if (x != ',')
+                  {
+                      part = part + x ;
+                  }
+                  else if (x == ',')
+                  {
+                      switch (part_number)
+                      {
+                          case 0 :
+                              product_id = part ;
+                              part = "" ;
+                              part_number ++ ;
+                              break;
+
+                          case  1 :
+                              product_name = part ;
+                              part = "" ;
+                              part_number ++ ;
+                              break;
+
+                          case 2 :
+                              product_price = part ;
+                              part = "" ;
+                              part_number ++ ;
+                              break;
+
+
+                      }
+                  }
+
+                  productCatalog.add(new Product(Integer.parseInt(product_id), product_name , Float.parseFloat(product_price))) ;
+
+
+
+            }
+        }
 
         // TODO:
         // - Read each line from products.csv
@@ -26,8 +73,7 @@ public class Main {
         // - The data in products.csv is guaranteed to be valid.
     }
 
-    public static void main(String[] args)
+    public static void main(String[] args) throws IOException {
-    {
         try {
             loadProducts();
         } catch (IOException e) {

src/main/java/ReportGenerator.java

@@ -1,22 +1,116 @@
+import java.io.IOException;
+import java.io.InputStream;
 import java.util.List;
+import java.util.Scanner;
 
 public class ReportGenerator {
 
     private final String ordersFilePath;
     private final List<Product> productList;
 
-    private double totalFinalCost;
+    private double totalFinalCost = 0;
-    private int totalQuantity;
+    private int totalQuantity = 0 ;
-    private double totalDiscountValue;
+    private double totalDiscountValue = 0 ;
-    private int totalInvalidLines;
+    private int totalInvalidLines = 0 ;
 
     public ReportGenerator(String ordersFilePath, List<Product> productList) {
         this.ordersFilePath = ordersFilePath;
         this.productList = productList;
     }
+    public static boolean isNumber(String str) {
+        try {
+            Integer.parseInt(str);
+            return true;
+        } catch (NumberFormatException e) {
+            return false;
+        }
+    }
+
+    public void processFile() throws IOException {
+        InputStream input = ReportGenerator.class
+                .getClassLoader()
+                .getResourceAsStream("products.csv");
+        if (input == null) {
+            throw new IOException("products.csv not found");
+        }
+        Scanner scanner = new Scanner(input);
+        while (scanner.hasNextLine())
+        {
+            String ln = scanner.nextLine() ;
+            int part_number = 0 ;
+            String part  = "";
+            String product_id = "" ;
+            String product_number = "" ;
+            String product_discount = "" ;
+            for (char x : ln.toCharArray() )
+            {
+
+                if (x != ',')
+                {
+                    part = part + x ;
+                }
+                else if (x == ',')
+                {
+                    switch (part_number)
+                    {
+                        case 0 :
+                            product_id = part ;
+                            part = "" ;
+                            part_number ++ ;
+                            break;
+
+                        case  1 :
+                            product_number = part ;
+                            part = "" ;
+                            part_number ++ ;
+                            break;
+
+                        case 2 :
+                            product_discount = part ;
+                            part = "" ;
+                            part_number ++ ;
+                            break;
+
+
+                    }
+                }
+
+                if (isNumber(product_id) && isNumber(product_number ) && isNumber(product_discount))
+                {
+                    int id = Integer.parseInt(product_id) ;
+                    int number = Integer.parseInt(product_number) ;
+                    int discount = Integer.parseInt(product_discount) ;
+
+                    if (id < 1 || id > 9 )
+                    {
+                        totalInvalidLines ++ ;
+                        continue;
+
+                    }
+                    if (number < 1)
+                    {
+                        totalInvalidLines ++ ;
+                        continue;
+                    }
+                    if (discount >= 100 || discount < 0 )
+                    {
+                        totalInvalidLines ++ ;
+                        continue;
+                    }
+
+
+                }
+                else {
+
+                    totalInvalidLines ++ ;
+                    continue;
+                }
+
+
+
+
+        }
 
-    public void processFile()
-    {
         // TODO:
         // 1. Open the order details CSV file
         // 2. Read the file line by line
@@ -80,4 +174,7 @@ public class ReportGenerator {
         ================================
         */
     }
-}
+}
+
+    public void saveReport() {
+    }