Merge pull request into develop from feature/csv-student-io

app/pom.xml

@@ -54,6 +54,12 @@
       <version>3.1.5</version>
     </dependency>
 
+    <dependency>
+      <groupId>org.apache.commons</groupId>
+      <artifactId>commons-csv</artifactId>
+      <version>1.14.1</version>
+    </dependency>
+
   </dependencies>
 
   <build>

app/src/main/java/ru/project/io/StudentCsvWriter.java

@@ -0,0 +1,88 @@
+package ru.project.io;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.nio.charset.StandardCharsets;
+import org.apache.commons.csv.CSVFormat;
+import org.apache.commons.csv.CSVPrinter;
+import ru.project.collection.MyList;
+import ru.project.student.Student;
+
+public class StudentCsvWriter {
+
+  private static final String GROUP_NUMBER_HEADER = "groupNumber";
+  private static final String AVERAGE_GRADE_HEADER = "averageGrade";
+  private static final String RECORD_BOOK_NUMBER_HEADER = "recordBookNumber";
+
+  private final String absoluteFilePath;
+
+  public StudentCsvWriter(String absoluteFilePath) {
+    this.absoluteFilePath = absoluteFilePath;
+  }
+
+  public void write(Student student) throws IOException {
+    ensureFileExists();
+
+    boolean fileIsEmpty = isFileEmpty();
+
+    try (CSVPrinter printer = createPrinter()) {
+      if (fileIsEmpty) {
+        writeHeader(printer);
+      }
+
+      writeStudent(printer, student);
+    }
+  }
+
+  public void write(MyList<Student>[] students) throws IOException {
+    ensureFileExists();
+
+    boolean fileIsEmpty = isFileEmpty();
+
+    try (CSVPrinter printer = createPrinter()) {
+      if (fileIsEmpty) {
+        writeHeader(printer);
+      }
+
+      for (MyList<Student> studentList : students) {
+        for (int i = 0; i < studentList.size(); i++) {
+          writeStudent(printer, studentList.get(i));
+        }
+      }
+    }
+  }
+
+  private CSVPrinter createPrinter() throws IOException {
+    BufferedWriter writer =
+        new BufferedWriter(
+            new OutputStreamWriter(
+                new FileOutputStream(absoluteFilePath, true), StandardCharsets.UTF_8));
+
+    return new CSVPrinter(writer, CSVFormat.DEFAULT);
+  }
+
+  private void writeHeader(CSVPrinter printer) throws IOException {
+    printer.printRecord(GROUP_NUMBER_HEADER, AVERAGE_GRADE_HEADER, RECORD_BOOK_NUMBER_HEADER);
+  }
+
+  private void writeStudent(CSVPrinter printer, Student student) throws IOException {
+
+    printer.printRecord(
+        student.getGroupNumber(), student.getAverageGrade(), student.getRecordBookNumber());
+  }
+
+  private void ensureFileExists() throws IOException {
+    File file = new File(absoluteFilePath);
+
+    if (!file.isFile()) {
+      throw new IOException("CSV file does not exist: " + absoluteFilePath);
+    }
+  }
+
+  private boolean isFileEmpty() {
+    return new File(absoluteFilePath).length() == 0;
+  }
+}

app/src/main/java/ru/project/search/StudentSearchService.java

@@ -1,7 +1,7 @@
 package ru.project.search;
 
-import ru.project.collection.MyLinkedList;
 import ru.project.collection.MyList;
+import ru.project.collection.MyLinkedList;
 import ru.project.student.Student;
 
 public class StudentSearchService {

app/src/test/java/ru/project/io/StudentCsvWriterTest.java

@@ -0,0 +1,194 @@
+package ru.project.io;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import ru.project.collection.MyLinkedList;
+import ru.project.collection.MyList;
+import ru.project.student.Student;
+
+class StudentCsvWriterTest {
+
+  @TempDir Path tempDir;
+
+  @Test
+  void writeShouldWriteHeaderAndStudentToEmptyFile() throws Exception {
+    Path file = tempDir.resolve("students.csv");
+    Files.createFile(file);
+
+    Student student = new Student("A12", 4.5, 10001);
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    writer.write(student);
+
+    List<String> lines = Files.readAllLines(file);
+
+    assertEquals(List.of("groupNumber,averageGrade,recordBookNumber", "A12,4.5,10001"), lines);
+  }
+
+  @Test
+  void writeShouldAppendStudentToExistingFile() throws Exception {
+    Path file = tempDir.resolve("students.csv");
+
+    Files.write(file, List.of("groupNumber,averageGrade,recordBookNumber", "A12,4.5,10001"));
+
+    Student student = new Student("B07", 3.8, 10002);
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    writer.write(student);
+
+    List<String> lines = Files.readAllLines(file);
+
+    assertEquals(
+        List.of("groupNumber,averageGrade,recordBookNumber", "A12,4.5,10001", "B07,3.8,10002"),
+        lines);
+  }
+
+  @Test
+  void writeShouldNotCreateMissingFile() {
+    Path file = tempDir.resolve("students.csv");
+
+    Student student = new Student("A12", 4.5, 10001);
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    assertThrows(IOException.class, () -> writer.write(student));
+
+    assertFalse(Files.exists(file));
+  }
+
+  @Test
+  void writeShouldAppendSeveralStudentsInOrder() throws Exception {
+    Path file = tempDir.resolve("students.csv");
+    Files.createFile(file);
+
+    Student student1 = new Student("A12", 4.5, 10001);
+    Student student2 = new Student("B07", 3.8, 10002);
+    Student student3 = new Student("C25", 4.9, 10003);
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    writer.write(student1);
+    writer.write(student2);
+    writer.write(student3);
+
+    List<String> lines = Files.readAllLines(file);
+
+    assertEquals(
+        List.of(
+            "groupNumber,averageGrade,recordBookNumber",
+            "A12,4.5,10001",
+            "B07,3.8,10002",
+            "C25,4.9,10003"),
+        lines);
+  }
+
+  @Test
+  void writeArrayShouldAppendStudentsFromAllListsInOrder() throws Exception {
+
+    Path file = tempDir.resolve("students.csv");
+    Files.createFile(file);
+
+    Student student1 = new Student("A12", 4.5, 10001);
+    Student student2 = new Student("B07", 3.8, 10002);
+    Student student3 = new Student("C25", 4.9, 10003);
+    Student student4 = new Student("D15", 4.2, 10004);
+    Student student5 = new Student("E20", 3.6, 10005);
+
+    MyList<Student> firstList = new MyLinkedList<>();
+    firstList.add(student1);
+    firstList.add(student2);
+
+    MyList<Student> secondList = new MyLinkedList<>();
+    secondList.add(student3);
+
+    MyList<Student> thirdList = new MyLinkedList<>();
+    thirdList.add(student4);
+    thirdList.add(student5);
+
+    @SuppressWarnings("unchecked")
+    MyList<Student>[] students = new MyList[] {firstList, secondList, thirdList};
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    writer.write(students);
+
+    List<String> lines = Files.readAllLines(file);
+
+    assertEquals(
+        List.of(
+            "groupNumber,averageGrade,recordBookNumber",
+            "A12,4.5,10001",
+            "B07,3.8,10002",
+            "C25,4.9,10003",
+            "D15,4.2,10004",
+            "E20,3.6,10005"),
+        lines);
+  }
+
+  @Test
+  void writeArrayShouldSkipEmptyLists() throws Exception {
+    Path file = tempDir.resolve("students.csv");
+    Files.createFile(file);
+
+    Student student = new Student("A12", 4.5, 10001);
+
+    MyList<Student> emptyList = new MyLinkedList<>();
+
+    MyList<Student> nonEmptyList = new MyLinkedList<>();
+    nonEmptyList.add(student);
+
+    @SuppressWarnings("unchecked")
+    MyList<Student>[] students = new MyList[] {emptyList, nonEmptyList, new MyLinkedList<>()};
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    writer.write(students);
+
+    List<String> lines = Files.readAllLines(file);
+
+    assertEquals(List.of("groupNumber,averageGrade,recordBookNumber", "A12,4.5,10001"), lines);
+  }
+
+  @Test
+  void writeEmptyArrayShouldNotModifyFile() throws Exception {
+    Path file = tempDir.resolve("students.csv");
+
+    List<String> initialContent =
+        List.of("groupNumber,averageGrade,recordBookNumber", "A12,4.5,10001");
+
+    Files.write(file, initialContent);
+
+    @SuppressWarnings("unchecked")
+    MyList<Student>[] students = new MyList[0];
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    writer.write(students);
+
+    assertEquals(initialContent, Files.readAllLines(file));
+  }
+
+  @Test
+  void writeEmptyArrayShouldNotCreateMissingFile() {
+    Path file = tempDir.resolve("students.csv");
+
+    @SuppressWarnings("unchecked")
+    MyList<Student>[] students = new MyList[0];
+
+    StudentCsvWriter writer = new StudentCsvWriter(file.toAbsolutePath().toString());
+
+    assertThrows(IOException.class, () -> writer.write(students));
+
+    assertFalse(Files.exists(file));
+  }
+}

app/src/test/java/ru/project/search/StudentSearchTest.java

@@ -3,8 +3,8 @@ package ru.project.search;
 import static org.junit.jupiter.api.Assertions.*;
 
 import org.junit.jupiter.api.Test;
-import ru.project.collection.MyLinkedList;
 import ru.project.collection.MyList;
+import ru.project.collection.MyLinkedList;
 import ru.project.student.Student;
 
 class StudentSearchTest {