Read and write summary of files in Android

In Android, files are divided into two main categories, internal storage and external storage

The files stored internally are private to the program and are divided into ordinary files and cache files.

External files can also be private or common, depending on the directory location of the file.

Common files can be handled in Java file processing, but internal files must be opened and closed with Openfileinput or openfileoutput

Check the status of the SD card (read/write, accessible, etc.) before operating the file on the SD card.

Read and write summary of files in Android