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Brizton Floyd
3,348 PointsRuntime Exception Only In WorkSpaces runs fine using IDE
Im not sure why im getting this error. My code compiles fine but at runtime im getting this exception. It's only occurring in workspaces and im not sure why. I have Intellij Idea and Eclipse and the code compiles and runs with no problem. I want to submit my project for review but don't want to loose points based on this issue here in workspaces. Does anyone have any idea about this ? As you can see from the stack trace the error is not coming from my custom class but seems to be coming from the ArrayList Collection somewhere.
Exception in thread "main" java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
at java.util.ArrayList$Itr.next(ArrayList.java:851)
at com.teamtreehouse.model.Roster.removeFromRoster(Roster.java:46)
at com.teamtreehouse.model.Coach.removePlayerFromRoster(Coach.java:125)
at com.teamtreehouse.model.Organizer.removePlayerFromTeam(Organizer.java:159)
at com.teamtreehouse.model.Organizer.makeSelection(Organizer.java:32)
at LeagueManager.main(LeagueManager.java:26)
2 Answers
Seth Kroger
56,413 PointsFrom Oracle docs: https://docs.oracle.com/javase/7/docs/api/java/util/ConcurrentModificationException.html
Note that this exception does not always indicate that an object has been concurrently modified by a different thread. If a single thread issues a sequence of method invocations that violates the contract of an object, the object may throw this exception. For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will throw this exception.
I'm guessing that you're using a for-each loop to search for an item to remove and remove it inside of the loop. This can cause errors because you're changing the iteration order while you are still iterating over the list.
Perhaps this SO thread will help: http://stackoverflow.com/questions/223918/iterating-through-a-collection-avoiding-concurrentmodificationexception-when-re
Brizton Floyd
3,348 PointsHello Seth I read the oracle docs and used an Iterator and it stopped the error. However when I execute the code in workspaces I still get the error. And when I run the code on intelli J Idea I don't get the error.
Seth Kroger
56,413 PointsWell, let's take a look at your code then.