Why does the construct work (java)?

Question

Java

www.quizful.net/interview/java/rewrite-a-code-with...
I'm interested in the answer:
if(System.out.printf("Hello world") == null){}
what does that even mean?
why is the helloworld still displayed if the condition body is empty?

Answer 1

Because the System.out.printf("Hello world") call is executed first, and only after that the result of the System.out.printf("Hello world") call is compared to null