Lecture 7: Storage Intro Flashcards
What does internal storage refer to?
Non-removable fixed memory within the device
What does external storage refer to?
Removable memory like a MicroSD
What type of storage does android prefer to install?
Internal storage
Where can apps specify if theyd like to be installed on external storage?
app manifest
Using internal and external storages impact the way __ is handled
file access
What storage type is used for code and cached data?
internal storage
What storage type is used for media, large files and data that needs to be shared?
external storage
What is App-Specific storage?
Storage for data specific to your app that doesn’t need to be shared with other apps
What permissions do app-specific storage requires?
none
Files can be listed from internal storage using?
Array<String> files = context.fileList();</String>
A specific file object can be retrieved from the array?
File file = new File(context.getFilesDir(), filename);
What is an alternative way to work with app-specific storage if you dont want to work with the file API provided by android?
streams
Explain the special form of app specific storage known as the ‘cache’
A place for your app to temporaily store data while in use.
What is the downside to using cache as temporary storage?
It might disappear at any time
Explain the 2 ways a cache can be cleared
- Android automatically empties the cache
- User manually clears the cache
How do you access the cache?
Create a new cache file
File.createTempFile(filename, null, context.getCacheDir());
Fetch an existing cache file
File cacheFile = new File (context.getCacheDir(), filename);
Files stored in the cache are simpled stored within a __ of the normal __ storage and can be otherwise treated as __
- subfolder
- app specific
- normal
How would you delete an existing file from storage?
Give 2 different ways
- call the delete() method on the File object
File coolFile = new File(context.getFilesDir(), “file.txt”);
coolFile.delete(); - use the context.deleteFile() to delete files based on name
context.deleteFile(“file.txt”);
What storage is an alternative to app-specfic storage?
Media storage
What is media storage?
A form of shared external storage for your application
Typically involved with media (images, video, etc)
What are the types of media that media storage stores?
Images, video, audio, downloads
Android uses a __ style querying system for fetching media
SQL
When querying media tables you can specify __ to retrieve and ___ clauses with specific requirements
- columns
- where
How do you access individual media files when using media storage?
Identify specific files using a query that provides the content uris or file descriptors
Pass them into the openFileDescriptor() method of a ContentResolver()
Try to open file
You cannot edit or overwrite files that you do not own. How would you be able to modify a file owned by another application
Create a modified copy of the file
What are the downsides of using media storage?
- Provides access to all the media storage but little in telling you where to look for a file
- Owner probably doesnt know the uri of a given file
What are the downsides of using media storage?
- Provides access to all the media storage but little in telling you where to look for a file
- Owner probably doesnt know the uri of a given file
- Little security, gives read premissions to almost everyone
