Error Message from RobotBase

I tried running my code onto my robot and I receive the following error:

Warning at edu.wpi.first.wpilibj.RobotBase.main( Robots should not quit, but yours did!
ERROR 1 The startCompetition() method (or methods called by it) should have handled the exception above. edu.wpi.first.wpilibj.RobotBase.main(

I tried looking through the RobotBase.class file but I was unable to find what exactly my problem was.

There’s an error in your robot code. This usually ends up being a NullPointerException by referencing a variable before it’s created, or creating multiple sensors or actuators with the same I/O port or ID.

If you share your code (or post a link to its repository, if you have one), we’ll be able to see the problem

That error is just RobotBase telling you that an error happened somewhere in your code. The actually helpful information is probably above that error in the output.

i am also having the same problem but i dont seem to be able to find the robtbase in my code.

Wait no i found it, i dont understand. it is exactly like y other codes that work and yet it still doesnt work.

If you post your code folks can help.

apparently i am a new user and chief delfi will not let me put the code file on here.

You can paste it into Code Block(s)

by surrounding the text with three backtics > ```

or you can try uploading it to a github account(or pastebin if really desperate) and link to it.

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To clarify OP (since this thread is back live):

Java source code (where the problem will be) are stored in .java files.

Java .class files are the output of the java compiler and generally are not the place to start searching for root cause on issues.

While debugging these sorts of issue the general advice I can provide:

  1. Start by looking at the first error you see in the log, not the last. The place the execution first “goes off the rails” is usually the most informative for where the problem is at. Subsequent errors are usually collateral damage from that initial issue.
  2. Understand the contents of the error message, which usually includes a Stack Trace.
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I am about to post my code onto get hub but first i thought it might be a good thing to let you know that there is a null pointer error first, i looked through my error log again after i saw what gerthworm said. the error is : “java.lang.nullpointerexception”

when i get my code onto get hub i will link it onto this reply.


here is my code.

In your Class you never initalize your DifferentialDrive drive variable. It looks like you were doing this in the init() method, but you later commented it out.

Thank you gixxy, i wasn’t to worried about the drive system. the problem i am facing is that every time i enable the robot, about 1 and a half seconds later the robot disables itself with an error. i am not currently around my robot so i don’t know if this will fix it though. another thing that i should mention is the fact that this is base code for another robot, i am currently using it to teach myself how to do more specific/advanced coding. The code itself is from another team.

Also gixxy i thank you for spending the time of day to sit here and help me work on my code. i unfortunately and the head coder of my-team and i dont know much about coding :smile:

So what’s happening, is that when you initialize the ExampleSubsystem m_subsystem it initializes the default command, ExampleCommand, for the subsystem, which leads to ExampleCommand’s execute() method being called, which then tries to call your ExampleSubsystem’s arcadeDrive() method which references the drive object. Because the drive variable was never initialized, it is null, thus your error.


thank you again gixxy for that, i am going to try out this code tomorrow and if all goes well i will start on my final draft of this code. bro like what FRC team are you apart of and how can i get a hold of you again if i need help?

I’m the Programming Mentor for Team 3468 MAGNATech. You can always direct message me here on Chief Delphi.

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7 posts were merged into an existing topic: Help with lidar code