implement saveReport method

src/main/java/Main.java

@@ -15,6 +15,7 @@ public class Main {
         }
         Scanner scanner = new Scanner(input);
 
+        //reading file line by line and then parsing their values
         while (scanner.hasNextLine()) {
             String line = scanner.nextLine();
             String[] cells = line.split(",");

src/main/java/ReportGenerator.java

@@ -1,4 +1,5 @@
 import java.io.*;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Scanner;
 
@@ -35,29 +36,29 @@ public class ReportGenerator {
                     int quantity = Integer.parseInt(fields[1]);
                     int discountPercent = Integer.parseInt(fields[2]);
                     // check if any field has wrong amounts
-                    if ((discountPercent < 0 || discountPercent > 100) || (quantity <= 0) || (!productList.contains(productID)))
+                    if ((discountPercent < 0 || discountPercent > 99) || (quantity <= 0) ||
+                            (productList.stream().noneMatch(product -> product.getProductID() == productID)))
                     { throw  new IllegalArgumentException(); }
 
-                    double subtotal = quantity * discountPercent / 100;
+                    Product p = productList.stream().filter(product -> product.getProductID() == productID).findFirst().get();
+                    double subtotal = quantity * p.getPrice();
                     double discountValue = subtotal * discountPercent / 100;
-                    double finalCost = subtotal + discountValue;
+                    double finalCost = subtotal - discountValue;
 
                     //updating report attributes
                     totalQuantity += quantity;
                     totalFinalCost += finalCost;
                     totalDiscountValue += discountValue;
                 }
-                catch (Exception e) {
+                catch (IllegalArgumentException e) {
                     totalInvalidLines++;
                     System.out.println("Inavalid line: " + lineNumber);
-                    continue;
                 }
-                finally {
+            }
             input.close();
-                }
-            }
 
         }
+
         catch (IOException e) {
             System.out.println("Orders file not found");
         }
@@ -66,26 +67,21 @@ public class ReportGenerator {
 
     public void saveReport()
     {
-        // TODO:
-        // 1. Build a formatted report string
-        // 2. Include:
-        //      - total quantity
-        //      - total final cost
-        //      - total discount value
-        //      - total invalid lines
-        // 3. Create/open output report file (name it report.txt)
-        // 4. Write report string into file
-        // 5. Handle file writing exceptions
-        // 6. Close writer resources
 
-        /* Example Structure
+        String report = "========= SALES REPORT =========\n" +
-        ========= SALES REPORT =========
+                "Total Quantity Sold: " + totalQuantity + "\n" +
-        Total Quantity Sold: 42
+                "Total Final Cost: " + totalFinalCost + "\n" +
-        Total Final Cost: $1520.75
+                "Total Discount Value: " + totalDiscountValue + "\n" +
-        Total Discount Value: $230.50
+                "Total Invalid Rows: " + totalInvalidLines + "\n" +
-        Invalid Rows: 3
+                "=======================================";
-        ================================
-        */
 
+        try {
+            PrintWriter output = new PrintWriter("report.txt");
+            output.println(report);
+            output.close();
+        }
+        catch (FileNotFoundException e) {
+            System.out.println("Error writing report file!");
+        }
     }
 }