Put 숙제

--UserDaoService.java
//delete, insert
public User update(User user, int id) {
    User deleteUser = deleteById(id);
    User saveUser = new User();

    if(deleteUser == null) {
        return null;
    } else {
        saveUser = save(user);
    }

    return saveUser;
}

--UserController.java

@PutMapping("/users/{id}")
public ResponseEntity<Object> updateUser(@RequestBody User user, @PathVariable int id) {
    User savedUser = service.update(user, id);

    if(savedUser == null) {
        throw new UserNotFoundException(String.format("ID[%s] not found", id));
    }

    return ResponseEntity.status(HttpStatus.NO_CONTENT).build();
}