completed service class and error handling

src/main/java/com/student/details/controllers/DetailsController.java

@@ -15,5 +15,4 @@ public class DetailsController {
     System.out.println("This is the students index route.");
   }
 
-
 }

src/main/java/com/student/details/exceptions/ErrorDetails.java

+package com.student.details.exceptions;
+
+import java.util.Date;
+
+public class ErrorDetails {
+    private Date timestamp;
+    private String message;
+    private String details;
+
+    public ErrorDetails(Date timestamp, String message, String details) {
+        this.timestamp = timestamp;
+        this.message = message;
+        this.details = details;
+    }
+
+    public Date getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(Date timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public String getDetails() {
+        return details;
+    }
+
+    public void setDetails(String details) {
+        this.details = details;
+    }
+}

src/main/java/com/student/details/exceptions/GlobalExceptionHandler.java

+package com.student.details.exceptions;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.context.request.WebRequest;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
+
+import java.util.Date;
+
+public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {
+    public ResponseEntity<?> resourceNotFoundException(ResourceNotFoundException ex, WebRequest webRequest) {
+        ErrorDetails errorDetails = new ErrorDetails(new Date(), ex.getMessage(), webRequest.getDescription(false));
+        return new ResponseEntity<>(errorDetails, HttpStatus.NOT_FOUND);
+    }
+}

src/main/java/com/student/details/exceptions/ResourceNotFoundException.java

+package com.student.details.exceptions;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.NOT_FOUND)
+public class ResourceNotFoundException extends Exception {
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+}

src/main/java/com/student/details/services/StudentService.java

 package com.student.details.services;
+import com.student.details.exceptions.ResourceNotFoundException;
+import com.student.details.models.Student;
+import com.student.details.repositories.StudentRepository;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
 @Service
 public class StudentService {
 
+    @Autowired
+    StudentRepository studentRepository;
+
+
+    public List<Student> findAllStudents() {
+        return studentRepository.findAll();
+    }
+
+
+    public Student addStudent(Student student) {
+        return studentRepository.save(student);
+    }
+
+    public Optional<Student> getStudentById(Long studentId) {
+        return studentRepository.findById(studentId);
+    }
+
+    public Student updateStudent(Long studentId, Student studentDetails) throws ResourceNotFoundException {
+        Student student = studentRepository.findById(studentId)
+                .orElseThrow(() -> new ResourceNotFoundException("Student id: " + studentId + " not found"));
+
+        student.setFirstName(studentDetails.getFirstName());
+        student.setLastName(studentDetails.getLastName());
+
+        Student updatedStudent = studentRepository.save(student);
+        return updatedStudent;
+
+    }
+
+    public Map<String, Boolean> deleteStudent(Long studentId) throws ResourceNotFoundException {
+        Student student = studentRepository.findById(studentId)
+                .orElseThrow(() -> new ResourceNotFoundException("Student id: " + studentId + " not found"));
 
+        studentRepository.delete(student);
+        Map<String, Boolean> response = new HashMap<String, Boolean>();
+        response.put("deleted", true);
+        return response;
+    }
 }