you can just load onc time

.idea/.gitignore

@@ -0,0 +1,10 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Ignored default folder with query files
+/queries/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
+# Editor-based HTTP Client requests
+/httpRequests/

.idea/compiler.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <annotationProcessing>
+      <profile name="Maven default annotation processors profile" enabled="true">
+        <sourceOutputDir name="target/generated-sources/annotations" />
+        <sourceTestOutputDir name="target/generated-test-sources/test-annotations" />
+        <outputRelativeToContentRoot value="true" />
+        <module name="WS-07-Multithreading-Basics-and-Hashing" />
+      </profile>
+    </annotationProcessing>
+  </component>
+</project>

.idea/encodings.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding">
+    <file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
+    <file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
+  </component>
+</project>

.idea/jarRepositories.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RemoteRepositoriesConfiguration">
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Central Repository" />
+      <option name="url" value="https://maven.devneeds.ir/" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Maven Central repository" />
+      <option name="url" value="https://repo1.maven.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="jboss.community" />
+      <option name="name" value="JBoss Community repository" />
+      <option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
+    </remote-repository>
+  </component>
+</project>

.idea/misc.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" project-jdk-name="25" project-jdk-type="JavaSDK" />
+</project>

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="" vcs="Git" />
+  </component>
+</project>

src/main/java/dev/Main.java

@@ -11,11 +11,14 @@ public class Main {
 
     public static void main(String[] args) throws Exception {
 
+        boolean once = true;
+
         Scanner scanner = new Scanner(System.in);
 
         StudentManager manager = new StudentManager();
 
         while (true) {
+            System.out.println("==================================");
 
             System.out.println("""
                     1.Load students
@@ -23,41 +26,59 @@ public class Main {
                     3.Remove student
                     4.Print students
                     5.Exit
+                    Chose:
                     """);
 
+
+
             int choice = scanner.nextInt();
 
+
             switch (choice) {
 
                 case 1 -> {
 
-                    List<String> data = FileManager.loadStudents("students.txt");
+                    if(once){
+                        List<String> data = FileManager.loadStudents("students.txt");
 
-                    // TODO:
+                        int n = data.size();
 
-                    // Split data into 3 parts
+                        List<String> part1 = data.subList(0 , n/3 );
 
-                    List<String> part1 = null;
+                        List<String> part2 = data.subList(n/3 , (2*n)/3);
 
-                    List<String> part2 = null;
+                        List<String> part3 = data.subList((2*n)/3 , n);
 
-                    List<String> part3 = null;
 
-                    // TODO:
 
-                    StudentLoader t1 = null;
+                        StudentLoader t1 = new StudentLoader(part1);
 
-                    StudentLoader t2 = null;
+                        StudentLoader t2 = new StudentLoader(part2);
 
-                    StudentLoader t3 = null;
+                        StudentLoader t3 = new StudentLoader(part3);
 
-                    // TODO:
+                        t1.start();
+                        t2.start();
+                        t3.start();
 
-                    // start()
+                        t1.join();
+                        t2.join();
+                        t3.join();
 
-                    // join()
+                        manager.addStudents(t1.getStudents());
+                        manager.addStudents(t2.getStudents());
+                        manager.addStudents(t3.getStudents());
+
+                        System.out.println("Loading Done");
+                        once = false;
+
+
+
+                    }
+                    else {
+                        System.out.println("you have load students befor");
+                    }
 
-                    // merge results
 
                 }
 
@@ -87,6 +108,7 @@ public class Main {
                         manager.printStudents();
 
                 case 5 -> {
+                    System.out.println("Good by");
                     return;
                 }
 

src/main/java/dev/model/Student.java

@@ -41,30 +41,27 @@ public class Student {
     @Override
     public int hashCode() {
 
-        // TODO:
-        // Return custom hash
+        return id % 97;
 
-        // Example:
-        // return id % 97;
-
-        return 0;
     }
 
     @Override
     public boolean equals(Object obj) {
 
-        // TODO:
+        if(obj == null){
+            return false;
+        }
 
-        // Step 1:
-        // Check null
+        Student std = (Student) obj;
 
-        // Step 2:
-        // Convert obj to Student
+        if(std.hashCode() == this.hashCode()){
+            return true;
+        }
+        else {
+            return false;
+        }
 
-        // Step 3:
-        // Compare IDs
 
-        return false;
     }
 
     @Override

src/main/java/dev/service/StudentManager.java

@@ -1,6 +1,7 @@
 package dev.service;
 
 import dev.model.Student;
+import dev.utils.FileManager;
 
 import java.util.ArrayList;
 
@@ -11,35 +12,38 @@ public class StudentManager {
 
     public void addStudents(ArrayList<Student> newStudents) {
 
-        // TODO:
-
-        // Merge students
-
-        // Hint:
-        // addAll()
+        this.students.addAll(newStudents);
 
     }
 
     public Student searchStudent(int id) {
 
-        // TODO:
-
-        // Loop through students
-
-        // Compare IDs
+        for(Student st : students){
+            if(st.getId() == id){
+                return st;
+            }
+        }
 
         return null;
     }
 
     public boolean removeStudent(int id) {
 
-        // TODO:
+        Student removeable = null;
 
-        // Find student
+        for(Student st: students){
+            if(st.getId() == id){
+                removeable = st;
+            }
+        }
 
-        // Remove student
+        if(removeable!= null){
+            students.remove(removeable);
+            return true;
+        }
 
         return false;
+
     }
 
     public void printStudents() {

src/main/java/dev/thread/StudentLoader.java

@@ -25,27 +25,15 @@ public class StudentLoader extends Thread {
     @Override
     public void run() {
 
-        // TODO:
-
-        /*
-        Example line:
-
-        1001,Aryan,Computer Science,3.7
-         */
-
         for (String line : lines) {
 
-            // TODO:
-            // split line
+            String[] data = line.split(",");
 
-            // TODO:
-            // read values
+            Student mystd = new Student(Integer.parseInt(data[0]) , data[1] ,
+                    data[2] , Double.parseDouble(data[3]));
 
-            // TODO:
-            // create Student
+            students.add(mystd);
 
-            // TODO:
-            // add to students list
 
         }
 

src/main/java/dev/utils/FileManager.java

@@ -18,9 +18,7 @@ public class FileManager {
 
         while ((line = reader.readLine()) != null) {
 
-            // TODO:
-
-            // Add line to list
+           lines.add(line);
 
         }