My nav program uses map tiles which are stored in a directory under external root.
When the program fails (application close, not reported error) the map file which was used ( = was read to a bitmap) sometimes is deleted from the directory.
How can these files be protected against deletion ?
I don't see any reason for the image files to be deleted. If your application fails with no error you should check the unfiltered LogCat and see if there are any messages.