Why ListPicker can not work?

You need a list block to feed the Elements property.

Also, in the future, please get screenshots of your blocks by right-clicking the blocks and selecting Download Blocks as PNG

Join a list block

is this correct?

Is this correct ?

I am guessing you want to use the List Picker for your BlueTooth device connection selection?

If so, here is a sample based on a ListView (close enough) and TinyDB.

(Canned Response)
These blocks can be dragged into your Blocks Editor to request permission(s) for Bluetooth scanning and connecting. All three parts are needed.

Thanks to @Anke for the original code.
My changes include

  • use of the Screen1 permission blocks to avoid the possibility of a typo
  • using a TinyDB tag particular to BT permissions and only for BT permissions.

Thank you, what is list block ? Where to get it ?

It was available about 6 months ago, I am using windows 7 operating system.

You can find it in the list category.

It seems that you haven't learned the basics of App Inventory, especially the List blocks.

A very good way to learn App Inventor is to read the free Inventor's Manual here in the AI2 free online eBook at App Inventor 2 Book: Create Your Own Android Apps. The links are at the bottom of the Web page. The book "teaches" users how to program with AI2 blocks.

There is a free programming course here Course In A Box and the AIA files for the projects in the book are here: App Inventor 2 Book: Create Your Own Android Apps.
How to do a lot of basic things with App Inventor are described here: How do you...?.

Also do the tutorials Tutorials for MIT App Inventor to learn the basics of App Inventor, then try something and follow the Top 5 Tips: How to learn App Inventor.

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