# Cannot find a class or type named “ParticleSystem”

**URL:** <https://discourse.processing.org/t/cannot-find-a-class-or-type-named-particlesystem/14394>\
**Category:** Beginners\
**Created:** [October 3, 2019, 11:23am UTC](https://discourse.processing.org/t/cannot-find-a-class-or-type-named-particlesystem/14394 "2019-10-03T11:23:08Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Andrea](https://avatars.discourse-cdn.com/v4/letter/a/c37758/32.png) [@Andrea](https://discourse.processing.org/u/Andrea)\
**Post date:** [October 3, 2019, 11:23am UTC](https://discourse.processing.org/t/cannot-find-a-class-or-type-named-particlesystem/14394/1 "2019-10-03T11:23:08Z")

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Hi! I’m a beginner at programming and coding (actually, I know nothing but what I’ve seen in tutorials) so I’ve been following Daniel’s tutorials on Youtube. The thing is that I’m stuck into this particular [tutorial](https://www.youtube.com/watch?v=vdgiqMkFygc), even though I’m copying everything he is doing, the message “Cannot find a class or type named “ParticleSystem”” keeps appearing and I don’t know what am I supposed to do.

Thanks for you attention, I hope you can help me, I’m very lost:upside\_down\_face:

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**Author:** ![kll](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kll/32/964_2.png) [@kll](https://discourse.processing.org/u/kll)\
**Post date:** [October 3, 2019, 11:32am UTC](https://discourse.processing.org/t/cannot-find-a-class-or-type-named-particlesystem/14394/2 "2019-10-03T11:32:51Z")

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hallo, possibly you need some files in your project

i recommend to start from a existing example:

-a- go  
PDE / Tools / add Tool / Examples /  
and load  
The Nature of Code 3  
Daniel Shiffman  
All examples from The Nature of Code book.

-b- with bad luck you might need to restart processing  
now find:  
PDE / File / Examples / Contributed examples / The Nature of Code / cp04\_systems /  
select like

- Exercise\_4\_03\_MovingParticleSystem  
and run it.  
there you see also the .pde you miss so much

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**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [October 3, 2019, 11:32am UTC](https://discourse.processing.org/t/cannot-find-a-class-or-type-named-particlesystem/14394/3 "2019-10-03T11:32:56Z")

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> [@Andrea](#):
>
> , the message “Cannot find a class or type named “ParticleSystem”” keeps appearing

[NatureOfCode.com/book/chapter-4-particle-systems/#44-the-particle-system-class](http://NatureOfCode.com/book/chapter-4-particle-systems/#44-the-particle-system-class)

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**Author:** ![Andrea](https://avatars.discourse-cdn.com/v4/letter/a/c37758/32.png) [@Andrea](https://discourse.processing.org/u/Andrea)\
**Post date:** [October 3, 2019, 3:10pm UTC](https://discourse.processing.org/t/cannot-find-a-class-or-type-named-particlesystem/14394/4 "2019-10-03T15:10:10Z")

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Thank you so much for all your answers!😊