Spring Boot ResponseEntity not Manupulating the HTTP Responses - spring

Question

I'm having a problem with response entity exception handling. as it is seen, my response entity error is not changing the HTTP response.
My Codes
public ResponseEntity<User> retriveUser(#PathVariable int id){
Optional<User> foundUser;
foundUser= userRepo.findById(id);
if(foundUser.get()==null) {
return new ResponseEntity<>(foundUser.get(),HttpStatus.HttpStatus.NOT_FOUND);
}
else {
return new ResponseEntity<>(foundUser.get(),HttpStatus.OK);
}
}

Answer 1

There are a few errors in your code, first of all the foundUser.get()==null part does not enter the if block because it throw an error. You can check the java document to find out why you throw an error.
It also needs to be HttpStatus.NOT_FOUND instead of HttpStatus.HttpStatus.NOT_FOUND.
In the "Not Found" line, so that the optionalUser.get() method does not give an error; you have to remove it too.
#GetMapping("/user/{id}")
public ResponseEntity<User> retrieveUser(#PathVariable int id) {
Optional<User> optionalUser = userRepo.findById(id);
if (!optionalUser.isPresent()) {
return new ResponseEntity<>(null, HttpStatus.NOT_FOUND);
} else {
return new ResponseEntity<>(optionalUser.get(), HttpStatus.OK);
}
}

Answer 2

You should not call get() method if value is not present. can you try like below
public ResponseEntity<User> retriveUser(#PathVariable int id){
Optional<User> foundUser = userRepo.findById(id);
if(foundUser.isPresent()) {
return new ResponseEntity<>(foundUser.get(),HttpStatus.HttpStatus.OK);
}else {
return new ResponseEntity<>(null,HttpStatus.NOT_FOUND);
//or just return not found status code
//return new ResponseEntity<>(HttpStatus.NOT_FOUND);
}
}

Answer 3

Although the current accepted answer has all the details it needs, i have added my suggestions here please take a look.
you can get rid of if else block
#RestController
#RequestMapping(path = "users")
static class UserController {
private final Map<Long, UserInfo> users = new HashMap<>();
UserController() {
users.put(1L, new UserInfo(1L, "User 1"));
users.put(2L, new UserInfo(1L, "User 2"));
}
#GetMapping(path = "{id}")
public ResponseEntity<UserInfo> get(#PathVariable("id") Long id) {
return findUserById(id)
.map(ResponseEntity::ok)
.orElse(new ResponseEntity<>(UserInfo.notFoundUser(), HttpStatus.NOT_FOUND));
}
Optional<UserInfo> findUserById(#NonNull Long id) {
return Optional.ofNullable(users.get(id));
}
static class UserInfo {
Long id;
String name;
public UserInfo() {
}
public UserInfo(Long id, String name) {
this.id = id;
this.name = name;
}
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;
}
static UserInfo notFoundUser() {
return new UserInfo(-1L, null);
}
}
}

Answer 4

change your code to below
if(foundUser.isPresent()) {
return new ResponseEntity<>(foundUser.get(),HttpStatus.OK);
} else {
return new ResponseEntity<>(foundUser.get(),HttpStatus.HTTP_VERSION_NOT_SUPPORTED);
}