Id already exists in the database Spring boot Mysql

In this tutorials will teach you how to do the validation in Spring boot.this tutorials continue from the last article if you are not read in the last article please read and come here .

it is checking the employee id is already exists or not. if it is exists display the warning message as
  “Employee ID Already Exists”

      if(!employeeRepo.existsById(employee.getEmployeeId()))
       {
           employeeRepo.save(employee);
           return employee.getEmployeeName() + "Saved";
       }
       else
       {
           System.out.println("Employee Id already Exists");
           return "Employee Id already Exists";
       }

Full Code

EmployeeServiceIMPL

package com.springschool.firstapp.service;

import com.springschool.firstapp.dto.EmployeeDTO;
import com.springschool.firstapp.entity.Employee;
import com.springschool.firstapp.repository.EmployeeRepo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.ArrayList;

@Service
public class EmployeeServiceIMPL implements EmployeeService{

    @Autowired
    private EmployeeRepo employeeRepo;

    @Override
    public String addEmployee(EmployeeDTO employeeDTO) {

       Employee employee = new Employee(
               employeeDTO.getEmployeeId(),
               employeeDTO.getEmployeeName(),
               employeeDTO.getEmployeeAddress(),
               employeeDTO.getEmployeeSalary(),
               employeeDTO.getContactNumbers(),
               employeeDTO.getNic(),
               employeeDTO.isActiveState()
       );
       if(!employeeRepo.existsById(employee.getEmployeeId()))
       {
           employeeRepo.save(employee);
           return employee.getEmployeeName() + "Saved";
       }
       else
       {
           System.out.println("Employee Id already Exists");
           return "Employee Id already Exists";
       }

    }
}

i have attached the video link below. which will do this tutorials step by step