Erel is right. Your code creates a new string for each "out += ". With a large array, that will be very slow and not memory-efficient. If you want to concatenate a long string, uses a StringBuilder (in Java or in B4A).
I am trying to convert, android.nfc.extra.ID=[B@41ad7298, to the UID as I am experiencing problems with the NFC record reader when I store GPS data and some text in a tag. I have also used a combination of UltraLight & MifareUltralight. with MifareUltralight when reading a page it seems to read for then 4 bytes per page.
So I am trying to understand the data so I can read it manually.
We have a project to scan many different tags types and store them in an SQL server so a presentation windows app can display the data.