What was the hardest to program this year in Java?

[FRC4ME]

Originally Posted by Lord_Jeremy

In regard to WPI crap, I ended up doing a bunch of extensions just so I would have my own inheritance tree to play with, and I had to fix some bugs along the way.

I wouldn't go so far as to call it "crap." Were you around in the days of IFI? The default code didn't really have bugs in it - I'll give you that - but its organization didn't make much sense. Lines like "extern volatile near unsigned long short VAR" were not uncommon, and many teams ended up using Kevin Watson's unofficial default code instead.

When I was on a high school, I wrapped all of WPI's classes as well. In fact, I'm beginning to wonder if that's what they want you to do. Let WPI handle the low-level hardware drivers and interactions with the FPGA, but write the high-level inheritance tree yourself.

[Robototes2412]

Mecanum drive was also up there

[michael714]

One thing that frustrated us was the 21 character limit for the User Message box in the Dashboard DriverStationLCD. I know that it's a holdover from the old system, but it would have been nice to be able to change that limit for the new driver station LCD. After reading the posts here, it sounds like it might have been possible to write a new class to override the limit, but as relatively beginner Java programmers, it was not entirely obvious.

Another bummer was the DefaultCode template. The Timer.delay() routine was not as useful as we thought it would be. We needed delays because of how our pneumatic kicker was designed, but we wanted the teleop periodic to keep looping as well. Timer.delay() did not allow that to happen. Eventually, we learned that we should have put our pneumatic code into a thread that is separate from our joystick read and motor control. But working with threads will be something new for our team. It would be nice to have a sample routine with some task in its own thread.

It wasn't very friendly that the DefaultCode template tells you that you should not use it. We understood not to use it as-is, but the comment at the beginning of the template was a bit offputting. A bit more commenting throughout would also be helpful- I'm going to send my suggestions to the folks at WPI. One specific point was the disable mode. Didn't understand when and how it could be used until shortly before the competition. Finally discovered that it allowed us to use the driver station to set our autonomous mode and that was very helpful.

Not directly related to Java, the Driver Station update process was frustrating. The deal about having to install, then uninstall, then reinstall was frustrating. And somehow we downloaded what we thought was the latest update, but when we got to the competition, we were told that it was not the latest update. They point to a date on the dashboard, but this indication was not described in any readme or release notes for the driver station update.

We did most of our debugging via System.out.println statements, but it seemed like occasionally those statements directly interfered with other code- no specific example at this time. Just curious if anyone else noticed that.

The WPIlib user guide for Java was not complete and so there were some things we wanted to know but were not described in the document.

When we tried to receive data from the NXT Magnetic Compass, we received an error message along the lines of "Invalid Manufacturer." Not sure if that was a Java problem or something else.

Had some problems getting digital inputs to show up on the dashboard using the Dashboard example code. The analog inputs showed up fine, but not the digital inputs.

Not sure why writing data to the DriverStationLCD was so time consuming, but we experienced that and noticed that others have made posts about it as well.

Things that we loved:

- The gyro class worked quite smoothly
- Being able to set autonomous mode via disabled mode was cool
- The Java was much easier to work with than Labview for those of us who have written code using text for years
- It was quite easy to implement holonomic drive code and it was beautiful to see the result
- Although I have my complaints about the DefaultCode template, in the end, we did write code that worked and we did implement our first successful autonomous code in 4 years (scored a goal in autonomous from the middle zone!)

[jhersh]

Originally Posted by FRC4ME

Oh, and I forgot to mention: finding and fixing bugs in WPI's code.

So far we're overriding three of WPI's classes with our own versions: PWM, because someone forgot to cast two integers to doubles before dividing them; Encoder, because someone divided by 0.25 when they should have divided by four; and DriverStation, because the scaling on the joystick axes is wrong (it goes from -1.0 to 0.9 rather than -1.0 to 1.0 due to the use of two's complement).

Not that I'm complaining; when volunteers write 20,000 lines of code there are bound to be a few errors. In fact, I'm glad WPILib isn't perfect, because then my programming team would have nothing to do after week one.

Have you reported all the bugs you found so that the library can be improved for everyone? Even better would be patches that implement the fixes.

Visit http://firstforge.wpi.edu/sf/tracker...wpilib/tracker to report bugs!

Thanks,
-Joe

[FRC4ME]

Originally Posted by jhersh

Have you reported all the bugs you found so that the library can be improved for everyone? Even better would be patches that implement the fixes.

Visit http://firstforge.wpi.edu/sf/tracker...wpilib/tracker to report bugs!

Thanks,
-Joe

Does the Java tracker actually get used? I noticed that, unlike the C++ tracker which has twelve bugs, the Java tracker only has one; the one that I submitted this January and has still not been fixed. Perhaps this is because, at least when I submitted that one, no Java developers' names were in the assignment list (only C++ and LabVIEW).

I will gladly fix them myself if that is possible. Can you explain further what the process of submitting a patch is? Thanks.

EDIT - I went ahead and submitted the other bugs to the tracker anyway.

[jhersh]

Originally Posted by FRC4ME

Does the Java tracker actually get used? I noticed that, unlike the C++ tracker which has twelve bugs, the Java tracker only has one; the one that I submitted this January and has still not been fixed. Perhaps this is because, at least when I submitted that one, no Java developers' names were in the assignment list (only C++ and LabVIEW).

I will gladly fix them myself if that is possible. Can you explain further what the process of submitting a patch is? Thanks.

EDIT - I went ahead and submitted the other bugs to the tracker anyway.

Sounds good...

I'm not sure why the Java guys aren't on the list. I can address the issues as well, if you don't find one.

If you fix them yourself, you can attach patchs to the artifacts and we'll apply them.

-Joe

[ksanger]

I joined Mak211 last year, three weeks before the ship date. The night before we had crashed our kicker as members had removed parts to modify without telling me. Kick, (too far), bend the forward bracket and eliminated the encoder so the return to reload the kick went back (too far) and destroyed the sensor telling it to stop. The morning of shipping we rebuilt the kicker.

But the most difficult part was that our position sensors on our four wheel steering kept coming loose. Plus we had no means of adjusting the wheels to a known starting position. After shipping we used a spare Crio to figure out how to make a Can Jaguar go from position control to speed control so we could rotate the wheels while reading the pots and displaying their position on the Dashboard. (Last year we were using C++ and to reconfigure the Cans we needed to destruct them then initialize them in either diagnostic speed mode or run position mode). I don't know if I can destruct them in Java and haven't seen a Java example that enables position mode.

Did I mention that I've never coded for C++ objects before? I have been using C since 1980, and I've only read about C++ before and I don't code for a living. Its amazing that we're teaching students Java for next year. Objects rule. Its going to be a while before I'm confident enough to write my own though. Maybe if I had the source I could modify that, but I haven't found the Java wpilibj source.

[davidthefat]

Oh silly me...

Servos

Yep thats right, servos... It took me a full week to figure out that the jumpers existed -__-... It was not software, but hardware so I guess it doesn't count?

[Anupam Goli]

Besides not being able to compile on any x64 OS?

I'd have to say IO. I remember that our head Programmer designed an IO Handler and wrote about half of an OS just so we could start designing our drive system, and autonomous never worked with the IOHandler.

That and the Vision systems. Maybe it was me, but after 4 hours of just trying to get the display to work on the classmate, nothing budged.

[synth3tk]

Originally Posted by michael714

Not sure why writing data to the DriverStationLCD was so time consuming, but we experienced that and noticed that others have made posts about it as well.

I waited for CD on that one. I remember figuring out how to set an autonomous mode during disable (which is a really cool trick [though I never got autonomous working]) right before researching the DriverStationLCD deal.

Other than that, 964's code was relatively simple, so we didn't go through the hassle of writing our own classes or anything exciting.

[jhersh]

Originally Posted by ksanger

(Last year we were using C++ and to reconfigure the Cans we needed to destruct them then initialize them in either diagnostic speed mode or run position mode).

This year the API has a changeMode method so you don't need to destroy the object and recreate it. Just call changeMode and then call enable.

Originally Posted by ksanger

I don't know if I can destruct them in Java and haven't seen a Java example that enables position mode.

In Java, there are no destructors and there is no delete. The lack of destructors is a limitation of the Squawk JVM that we are using. Objects with no references to them are destroyed by the garbage collector.

-Joe

[rrossbach]

Originally Posted by ksanger

Maybe if I had the source I could modify that, but I haven't found the Java wpilibj source.

FYI the wpilibj source is installed when you install the FRC plugins in Netbeans. The default location is %UserProfile%\sunspotfrcsdk\lib\WPILibJ\src (and the WPILibJ directory contains the Netbeans project for building the library).

- Ron
Team #2607 controls mentor