Lecture 7: Storage Intro

Question 1

What does internal storage refer to?

Answer 1

Non-removable fixed memory within the device

Question 2

What does external storage refer to?

Answer 2

Removable memory like a MicroSD

Question 3

What type of storage does android prefer to install?

Answer 3

Internal storage

Question 4

Where can apps specify if theyd like to be installed on external storage?

Answer 4

app manifest

Question 5

Using internal and external storages impact the way __ is handled

Answer 5

file access

Question 6

What storage type is used for code and cached data?

Answer 6

internal storage

Question 7

What storage type is used for media, large files and data that needs to be shared?

Answer 7

external storage

Question 8

What is App-Specific storage?

Answer 8

Storage for data specific to your app that doesn’t need to be shared with other apps

Question 9

What permissions do app-specific storage requires?

Answer 9

none

Question 10

Files can be listed from internal storage using?

Answer 10

Array<String> files = context.fileList();</String>

Question 11

A specific file object can be retrieved from the array?

Answer 11

File file = new File(context.getFilesDir(), filename);

Question 12

What is an alternative way to work with app-specific storage if you dont want to work with the file API provided by android?

Answer 12

streams

Question 13

Explain the special form of app specific storage known as the ‘cache’

Answer 13

A place for your app to temporaily store data while in use.

Question 14

What is the downside to using cache as temporary storage?

Answer 14

It might disappear at any time

Question 15

Explain the 2 ways a cache can be cleared

Answer 15

• Android automatically empties the cache
• User manually clears the cache

Question 16

How do you access the cache?

Answer 16

Create a new cache file
File.createTempFile(filename, null, context.getCacheDir());

Fetch an existing cache file
File cacheFile = new File (context.getCacheDir(), filename);

Question 17

Files stored in the cache are simpled stored within a __ of the normal __ storage and can be otherwise treated as __

Answer 17

• subfolder
• app specific
• normal

Question 18

How would you delete an existing file from storage?
Give 2 different ways

Answer 18

• 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”);

Question 19

What storage is an alternative to app-specfic storage?

Answer 19

Media storage

Question 20

What is media storage?

Answer 20

A form of shared external storage for your application

Typically involved with media (images, video, etc)

Question 21

What are the types of media that media storage stores?

Answer 21

Images, video, audio, downloads

Question 22

Android uses a __ style querying system for fetching media

Answer 22

SQL

Question 23

When querying media tables you can specify __ to retrieve and ___ clauses with specific requirements

Answer 23

• columns
• where

Question 24

How do you access individual media files when using media storage?

Answer 24

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

Question 25

You cannot edit or overwrite files that you do not own. How would you be able to modify a file owned by another application

Answer 25

Create a modified copy of the file

Question 26

What are the downsides of using media storage?

Answer 26

• 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

Question 27

What are the downsides of using media storage?

Answer 27

• 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