How to put an indicator if it was expand or collapse ?

[ghost]

Implement same thing like website accordion. It has an icon as indicator to whether its expand or collapse.

Here an example : https://roaderapp.com/faq.html

[cachapa]

Set a listener using setOnExpansionUpdateListener(OnExpansionUpdateListener listener).

The callback gives you the expansion ratio as a float from 0 (collapsed) to 1 (expanded). Simply set your bitmap accordingly.

[ghost]

Thanks for quick reply.