package store; import model.Student; import java.util.*; public class StudentStore { private Map students = new HashMap<>(); public Optional addStudent(Student student) { int id = students.size(); student.setId(id); students.put(id, student); return Optional.ofNullable(student); } public Optional getStudent(int id) { return Optional.ofNullable(students.get(id)); } public Set getAllStudents() { return new HashSet<>(students.values()); } public Optional updateStudent(Student student) { int id = student.getId(); if (students.containsKey(id)) { students.put(id, student); return Optional.ofNullable(student); } return Optional.empty(); } public boolean deleteStudent(int id) { return students.remove(id) != null; } }