In these cases, I try to write some functional tests first (such as calling restful endpoints and checking the response, or using a headless browser). Not great but much better than nothing. Any ideas on how to do it better?

That's false. A list object may be initialized but be empty (making it's length zero). Or it may not be initialized (making it null).

Both conditions may happen independently of one another. He checks for the null first so that checking the length does not throw a NPE.

> The if-statement is a good summary of what is wrong with Java.

Frankly, I see nothing wrong here.

Also, having an implied "conditional" that must be extracted by reading the head-portion of a loop is very very unreadable. I'd reject your submission on a code-review.

Instead, you should do something like below. I assume that your example is contrived, so for the sake of argument, assume I have all sorts of business cruft around mine. I.e. should_process exists because there are business rules for processing/not processing the master_list.

    def should_process(master_list):
        return master_list is not None and len(master_list) > 0

    def main_doing_of_stuff_foo():
        if not should_process(masterList):
            return  # Yes, this thing should be in its own method so you can do an early exit.

        for item in masterList:  # Yes, you should be using an iterator as well, not indexing.
            print("Body goes here".)

Doesn't it check if a list isn't null and then if the list has at least one item in it? Or are you simply saying the for loop takes care of the situation where there are 0 items in the list?

  masterList[a].list2.length()

  masterList[z].list2.length()