It was the case some years ago that most GUI development was in
C++, but that is long gone, and except at the very high end of GUIs it is overkill.
In the last year my firm has handled exactly
1 C++ GUI job, even then we asked them if they really meant it.
GUI development is a noticeable part of quant finance, yes really, I'd forecast that Baruch grads will spend 5-10% of their working life doing GUI of some form, but don't sweat if you have no skills in GUI, since any hiring manager who asked about GUI would expose the fact that it's a crap "pseudo quant" role.
If you have basic skills in Excel GUI development, it will make you a marginally more useful employee.
Java is a far from ideal GUI tool, but that doesn't stop it being common...
The friend of Yuriy may be happy, but it is worth pointing out that some employers and headhunters will try to suck you into pure IT roles.
They blur the line between a quant/developer and a straight developer.
In the first year the base salaries will be the same, but the net present value of an IT role is massively less than most quant jobs.
It's not always easy to spot that difference, since I have to sadly say that some HHs will lie to you on this, though fortunately they usually do this with profound incompetence.
What's more difficult is when the hiring manager isn't that straight with you.
As well as being asked about GUI, it's a bad sign when the programming aspect of the interview is too dominant.
There are a couple of banks who use Java in real quant work, but in most cases it is a bad sign if they explicitly ask for it.
This comes about since there are a lot of "bouncer" jobs out there.
Most doormen on clubs have a really boring role, standing in the rain dealing with irritating drunk people.
But occasionally they have a really exciting time, when it gets violent.
Same with mock-quant roles. 90% of the time is the heavy lifting of investment banking work. Feeding data into packages, debugging, altering parameters, and knocking up little GUIs to allow your betters to use some part of the system. Quant skills are prized because tyou understand the language and don't have to be told that if you see a bond price of 5.87, it's actually the yield.