try to fix SonarQube bug - A "NullPointerException" could be thrown

Question

I am facing one strange Sonar issue - A "NullPointerException" could be thrown.

Below is my service implementation class. emailNotificationServiceClient is FeignClient Interface which works fine.

      try {
        // send POST request
        ResponseEntity<GenericRes<?>> response = emailNotificationServiceClient.sendEmail(payload);
        // check response
        if (response != null) {
            if (response.getStatusCode() == HttpStatus.OK)
                log.info("Email Send Successful : {}", response.getBody());
            else
                log.info("Email Send Failed : {}", response.getBody());

            if (response.getBody() != null && response.getBody().getMessage() != null && !response.getBody().getMessage().isEmpty())
                return CompletableFuture.completedFuture(response.getBody().getMessage());
        }
    } catch (Exception e) {
        log.error("Error while sending email - sendEmailNotification in esb", e);
        return CompletableFuture.completedFuture(e.getMessage());
    }

GenericRes class -

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class GenericRes<T> {

    private String message;
    
    private T data;

}

I know that I have to add null check for object and then I should use that object. I have tried that but it won't work.

I have also tried Java 8 Optional.ofNullable but still facing same problem.

Answer 1

It is a false positive. SonarCube's rule is a bit "dumb". But you should be able to help it out ... something like this:

GenericRes<?> body = response.getBody();
if (body != null) {
    String message = body.getMessage();
    if (message != null && !message.isEmpty()) {
        return CompletableFuture.completedFuture(message);
    }
}

To my mind, that is more readable than the versions that SonarCube is having trouble with. So, that is a "win - win" solution.