# Box2D example not building

**URL:** <https://discourse.processing.org/t/box2d-example-not-building/46353>\
**Category:** Processing for Android\
**Created:** [May 9, 2025, 10:24am UTC](https://discourse.processing.org/t/box2d-example-not-building/46353 "2025-05-09T10:24:21Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![RichardDL](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@RichardDL](https://discourse.processing.org/u/RichardDL)\
**Post date:** [May 9, 2025, 10:24am UTC](https://discourse.processing.org/t/box2d-example-not-building/46353/1 "2025-05-09T10:24:22Z")

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Hi, I’m trying the basic examples for Android. On [Processing for Android](https://android.processing.org/tutorials/sensors/), when I run the example from just below “A more complex example using Box2D”, it complains:

```auto
No library found for shiffman.box2d
No library found for org.jbox2d.collision.shapes
No library found for org.jbox2d.common
No library found for org.jbox2d.dynamics

```

I couldn’t find the library in “Manage Libraries” so followed the link trail and downloaded from [Box2D for Processing](http://shiffman-archive.netlify.app/p5/libraries/box2d_processing/box2d_processing.zip). Then copied box2d\_processing to ‘sketchdir’\libraries.

That cleared those errors, but now I have these two:

```auto
The class Box does not exist.
The class Wall does not exist.

```

What have I missed?

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<div class="post-metadata">

**Author:** ![Max\_Normal](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/max_normal/32/20757_2.png) [@Max\_Normal](https://discourse.processing.org/u/Max_Normal)\
**Post date:** [May 17, 2025, 7:25am UTC](https://discourse.processing.org/t/box2d-example-not-building/46353/2 "2025-05-17T07:25:43Z")

</div>

If you are building on top of Shiffman examples then I think that you’ll find that the Box and Wall classes are defined elsewhere in the sample code and not in Box2D,