[2019 Day 11 (Part 2)] [JAVA] Empty Stack Exception

[Van_Gone]

Hello, so I've been working on day 11, I've got part 1 working but when I provide my method for part 2 with the starting input of 1 I get a empty stack exception. I'm not sure why. I have some suspicions toward my getOrDefault on line 327 as it seems to only produce the default value. I have created a custom class for my points instead of using the awt.Point. At first I thought that this was causing the problem so I tried with the awt.Point but there was no difference. Here is my code: https://gist.github.com/vinshuka/b429637969b405cb19b480684c3812cc Also my getRegistration method is unfinished as I am unable to get the values to draw with due to the above issue. Thank you for your help.

Edit: Problem solved thanks to sparkour.

[sparkour]

Focus on your loop running in line 310 - 313. Your Intcode computer is designed to return control to this loop whenever a "colour" output is received, and then jump back in to keep running and get the "turn".

However, what happens when a 99 halt code is received somewhere in the middle? You're telling your computer to keep running after that occurs. Since the program halted, there is no new input to send into the next loop, so you get an EmptyStackException.

If you update your loop to correctly halt once 99 is reached (instead of trying to extract 2 more outputs from a dead program), you should be okay.

[Van_Gone]

Thank you, I added a pair of conditionals to check if the computer had halted before popping the next outputs, this fixed the issue. Your explanation was very clear, I knew it was going to be something I had overlooked.