Supposed I have two API:

one for get customer name and another for updates customer name

I have two request simultaneously for updates customer name, how to auto handle this concurrency and Don’t occur race condition?

Because I don’t see any real world example to use synchronized for this scenario.

Can you help me and explain?

package com.example.customerapp.model;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;

@Entity
public class Customer {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String email;

    // Getters and setters
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

package com.example.customerapp.dao;

import com.example.customerapp.model.Customer;
import org.springframework.data.jpa.repository.JpaRepository;

public interface CustomerRepository extends JpaRepository<Customer, Long> {
}

package com.example.customerapp.service;

import com.example.customerapp.dao.CustomerRepository;
import com.example.customerapp.model.Customer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.Optional;

@Service
public class CustomerService {
    @Autowired
    private CustomerRepository customerRepository;

    public Optional<Customer> getCustomerById(Long id) {
        return customerRepository.findById(id);
    }

    public Customer saveOrUpdateCustomer(Customer customer) {
        return customerRepository.save(customer);
    }
}

package com.example.customerapp.controller;

import com.example.customerapp.model.Customer;
import com.example.customerapp.service.CustomerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.Optional;

@RestController
@RequestMapping("/customer")
public class CustomerController {
    @Autowired
    private CustomerService customerService;

    @GetMapping("/{id}")
    public ResponseEntity<Customer> getCustomer(@PathVariable Long id) {
        Optional<Customer> customer = customerService.getCustomerById(id);
        return customer.map(ResponseEntity::ok)
                .orElse(ResponseEntity.notFound().build());
    }

    @PutMapping
    public ResponseEntity<Customer> updateCustomer(@RequestBody Customer customer) {
        Customer savedCustomer = customerService.saveOrUpdateCustomer(customer);
        return ResponseEntity.ok(savedCustomer);
    }
}