I note that other apps (testing on Android) like WhatsApp, etc have folders that contains images the user has used/downloaded. These folders (like WhatsAppImages) are visible in other apps (Gallery/File Explorers, etc) so you can use those files to share, delete, etc like any other file.
In my codenameone app I download image files but they cannot be seen anywhere on the local device. I understand that for security apps run in a sandbox and this may be why.
But how do these other apps make their downloaded files visible to the general file system and other apps ?
Many Thx