That's the traumatizing way. Not bad if you have one mapped function. Terrible if you have dozens. Stepping through code should not require setting more than one breakpoint - but if I have to find where a set of chained method calls goes wrong I have to breakpoint-binary-search to the problem.

When you have "if" statements, you can press "next" repeatedly in Eclipse/IntelliJ/whatever and step through the code. When you use chained method calls you're constantly going into and out of function calls, and all the local variables become return values that you don't ever necessarily get to see in a stack frame, and sometimes you have to step through loads of boilerplate to see the next interesting line of code, even when you're doing something totally simple.

I feel your pain. Having to manually unwind chained calls just to see which one caused the NPE or whatever is obnoxious and kind of defeats the purpose of this style of coding. IDE's really need support for this.

Intellij can drop breakpoints on the Either::map, or in the lambda contained therein. It's really not much different than debugging the if version.

The problem isn't breakpoints so much as stepping through them. You either step through the whole chained method at once, or have to set a breakpoint inside of it. Whereas with loops you can step through loop iterations easily with no additional work.

Honestly, this hasn't been a problem. If I get a bad result I merely figure out where I went from a left to a right (and there will only be one spot where that happened), and debug that function only. I've never had to debug the entire chain from top to bottom, ever.

But if you're really worried, set a breakpoint in each lambda (trivial in IntelliJ) and use continue instead of step over.

Please remove your downvote. You shouldn't use it to disagree with a viable suggestion. Your comment made your argument nicely!

Ok, I agree with you. Someone needs to patch Java and other IDEs to allow breakpoints on periods. Double clicking a dot to set a breakpoint sounds like awesome UX. Why hasn't this been done?

I didn't downvote you.

Breakpoints on periods and the ability to step through them. Honestly if I have to use more than one breakpoint to find a problem because stepping doesn't work, I'm unhappy.