How does Android determine how to open a file? I ask because I have downloaded some PDFs and when I go into the Downloads folder I see that all of them, other than one, are marked with the Adobe Reader symbol and Android offers a choice of Adobe Reader or Quick Office and opens the file OK using either. The one exception is a file with extension .pdf but no symbol and Android flashes a message saying "Cannot open file" when I click on it.
Yet when I go into a file explorer app (Total Commander) the rogue file opens OK in both Adobe and Quick Office, and if I upload that file to my Windows PC it again opens OK in Adobe. So I assume that Android does not simply examine the file extension, there is something in the file content that tells Android how to open it. Or what?
Yet when I go into a file explorer app (Total Commander) the rogue file opens OK in both Adobe and Quick Office, and if I upload that file to my Windows PC it again opens OK in Adobe. So I assume that Android does not simply examine the file extension, there is something in the file content that tells Android how to open it. Or what?