From 3b09d15163ab8d838b393219cc5d750b5d33daf4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=95=D1=80=D1=88=D0=BE=D0=B2=20=D0=92=D0=BB=D0=B0=D0=B4?=
 =?UTF-8?q?=D0=B8=D1=81=D0=BB=D0=B0=D0=B2?= <ershvladislav@gmail.com>
Date: Mon, 31 Aug 2026 22:30:45 +0700
Subject: [PATCH] feat: reworking StudentCsvReader. Added the aability to
 specify row number when an exception is thrown out

---
 .../project/datasource/StudentCsvReader.java  | 27 ++++++++++++-------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/app/src/main/java/ru/project/datasource/StudentCsvReader.java b/app/src/main/java/ru/project/datasource/StudentCsvReader.java
index 7e39bee..156608e 100644
--- a/app/src/main/java/ru/project/datasource/StudentCsvReader.java
+++ b/app/src/main/java/ru/project/datasource/StudentCsvReader.java
@@ -25,7 +25,10 @@ public class StudentCsvReader implements Iterator<Student> {
     private final CSVParser parser;
     private final Iterator<CSVRecord> records;
 
+    private int lineOfFile;
+
     public StudentCsvReader(String absoluteFilePath) {
+        lineOfFile = 0;
         Path path = Paths.get(absoluteFilePath);
         if (!path.isAbsolute()) {
             throw new IllegalArgumentException("File path must be absolute");
@@ -51,6 +54,7 @@ public class StudentCsvReader implements Iterator<Student> {
 
     @Override
     public Student next() {
+        lineOfFile++;
         if (!records.hasNext()) {
             throw new NoSuchElementException();
         }
@@ -58,16 +62,21 @@ public class StudentCsvReader implements Iterator<Student> {
         CSVRecord record = records.next();
         if (record.size() != 3) {
             throw new IllegalArgumentException(
-                    "Expected 3 columns, but got " + record.size());
+                    "Problem at line " + lineOfFile + ".Expected 3 columns, but got " + record.size());
+        }
+        try {
+            double averageGrade = Double.parseDouble(record.get(AVERAGE_GRADE));
+            int recordBookNumber = Integer.parseInt(record.get(RECORD_BOOK_NUMBER));
+            return new StudentBuilder()
+                    .setGroupNumber(record.get(GROUP_NUMBER))
+                    .setAverageGrade(averageGrade)
+                    .setRecordBookNumber(recordBookNumber)
+                    .build();
+        }
+        catch (NumberFormatException e){
+            throw new IllegalArgumentException(
+                    "Problem at line " + lineOfFile + ". Unacceptable type convertation");
         }
-
-        double averageGrade = Double.parseDouble(record.get(AVERAGE_GRADE));
-        int recordBookNumber = Integer.parseInt(record.get(RECORD_BOOK_NUMBER));
-        return new StudentBuilder()
-                .setGroupNumber(record.get(GROUP_NUMBER))
-                .setAverageGrade(averageGrade)
-                .setRecordBookNumber(recordBookNumber)
-                .build();
     }
 
     private static void validateHeader(Map<String, Integer> headerMap) {