I don't see any 'good' or 'bad' practices here.
Please, correct me if I'm wrong.
For me, this question is rather a matter of taste. Because at the end of the day you end with the same instructions, the only difference is the structure of the code.
Hence there are no other differences the choice must be based on readability. And as for me, for-loop is more readable due to its conciseness.

still no answer, some kind of magic... :)

right, there is also "getOrDefault" method - may be worth to consider.

I was worried the Garbage Collector might get bored if it had nothing to do.

Also computationally inefficient, because each time an element gets evaluated, it is compared with all the existing lists. But I loved the functional approach.

You're right, although String.repeat() was only added since Java 11 and won't work on java 8...

i agree a while loop might be more readable here, thanks

It depends on how you approach the problem. I've found the Streams in Java to be great for declarative-style programming. I don't have to keep track of a "sum" or "min" variable, or even an "i" counter for the for loop. I just declare the function I want and it's all processed for me by the stream. While it maybe runs slower, such micro-optimizations are outweighed by readability. "Easier to understand" is in the eye of the team working on the code.

Appreciate the feedback!

Maybe he can't see the picture?

see the picture - the balls don't sit exactly on top of each other. For 3 layers the height is a little bit less than 3 diameters

EDIT: see the picture Visuallize a rack of pool/snooker balls stacked in a triangle - the balls don't sit exactly on top of each other. For 3 layers the height of that triangle is a little bit less than 3 diameters

visualize how they would be stacked

i love you my man! <3