Have you ever been forced to work with a younger and far less experienced colleague and in turn for being nice to him been lectured about basic stuff which he thinks he knows better (but he doesnt)? Gosh, I haven't been this angry in years...

Restraint.

@kunashe I try to, but I have the feeling that only encourages these kind of people in their 'superiority'

Its terrible!

I havnt been in this specific position but the feeling is oddly familiar. I assume that, like me, you're just a nice guy. What I would do is ask him carefully crafted leading questions, that make him arrive at the conclusion that he's a complete and utter noob. The key is to be very subtle and indirect so it rings very authentic to this idiot l. Once he's internalized this and arrived at it organically, it should make his bitch noob ass pipe down and be more appreciative of your help and patience. Some would call this a condescending approach, but like I said, I've been there and it's a furiously frustrating feeling.

In that case, can't you just let him sweat with it and wait for him to ask for help?

I have worked with loads of people like that. I don't let it get to me. Juniors usually want to prove their worth and want to feel important. I just let it happen. To make my life easier I usually pretend that I'm "daddy pig" from the "Peppa Pig" cartoon and the junior is Peppa. Makes life *a lot* easier. Don't take things too personally, as per Oscar Wilde: "life is too important to be taken seriously". All the best mate!

That's just immaturity. Junior devs are reeling of that attitude.