The android documentation has the following options below but does not explain what circumstances each is best for. What are the pros and cons of each method? e.g. Under what conditions would SQL be better than Shared Preferences?
Shared Preferences
Internal Storage
External Storage
SQLite Databases
Network Connection
Different Storage options in Android
Content Providers
Consider the structured data added to the device from application1 is
not accessible to another application2 present in the same device but
the profile photo added to the device by application1 is available to
the application2 running in the same device
Consider android device as a city, the applications in it are the
houses in the city, people in the houses(application) are the data.
Now content provider is like an broker in the city(android device).
This broker provide access for the people in the city for finding
different houses referring as the content provider in the android
device provide access for the data in the device for different
applications.
Shared Preferences
Consider I have an App say a Face book App which I use to log in to
my account.
Now the very first time I enter my username and password to get
access to my account. Say I log out of the application an hour later
again I use the same Face book App to login again to my application.
I have to enter username and password again to login to my account
and I set a theme to my application and other settings on how my app
looks in my current phone
This is un-necessary because consider I am using my phone to login to
the application. So I will always use my phone to login again and
again, thus entering my credentials again and again is more work
shows it’s not a user friendly app
Shared Preferences is very handy in such scenarios where I can use
its feature to share my data in a xml file Which physically exists in
the Android app installed in my phone which is not destroyed even if
the app is closed. Here we can save user preferences data of the
current application.
As a result next time I open my app in my phone I can see the data
automatically filled in the necessary fields and the settings are
File Storage
In Android we can use the device storage space to store the data in
it for the applications. The type of data involves things such as a
text file, image file, video file, audio file etc.
As seen in the figure as we can see that there are two places we can
do this. One way is to write the raw files into primary /secondary
storage. Another way is to write the cache files into the
primary/secondary storage.
There is also difference between storing raw data and the cache data,
the raw data once stored in memory by user has to be explicitly
deleted by the user explicitly otherwise it would exist till then.
Cache data stored in memory is not a permanent data because the
system automatically deletes it if it feels there is shortage of
memory.
Internal Storage:
Consider a user in an application has stored data in internal
storage, then only that user of that application has access to that
data on the mobile and that data is automatically deleted when the
user uninstalls the application. Speaking of which internal memory is
private.
The apps internal storage directory is stored using the name package
name in a special place in the android file system.
Other apps or users of current app have no access to the file set by
a particular user and a particular app unless it is explicitly made
available to the user for readable/writable access.
SQLite
Sqlite is used to store more structured data locally in a mobile
where the android app is running. Structured data involves as of
which shown in the figure like a student’s information in the form of
rows and columns.
Sqlite offers similar functionality like Mysql and oracle but with
limited functional features. Some of the things involve performing
query operations on tables. There are features though like creating
views but also some features are not available like stored procedure.
Sqlite is very helpful in storing complex and large data which can be
downloaded once and can be used again and again until the application
is running. When the application is closed the sqlite database is
also destroyed.
Putting all the pieces together
Shared preferences are good for storing ... an application's preferences, and other small bits of data. It's a just really simple persistent string key store for a few data types: boolean, float, int, long and string. So for instance if my app had a login, I might consider storing the session key as string within SharedPreferences.
Internal storage is good for storing application data that the user doesn't need access to, because the user cannot easily access internal storage. Possibly good for caching, logs, other things. Anything that only the app intends to Create Read Update or Delete.
External storage. Great for the opposite of what I just said. The dropbox app probably uses external storage to store the user's dropbox folder, so that the user has easy access to these files outside the dropbox application, for instance, using the file manager.
SQLite databases are great whenever you are going to use a lot of structured data and a relatively rigid schema for managing it. Put in layman's terms, SQLite is like MySQL or PostgreSQL except instead of the database acting as a server daemon which then takes queries from the CGI scripts like php, it is simply stored in a .db file, and accessed and queried through a simple library within the application. While SQLite cannot scale nearly as big as the dedicated databases, it is very quick and convenient for smaller applications, like Android apps. I would use an SQLite db if I were making an app for aggregating and downloading recipes, since that kind of data is relatively structured and a database would allow for it to scale well. Databases are nice because writing all of your data to a file, then parsing it back in your own proprietary format it no fun. Then again, storing data in XML or JSON wouldn't be so bad.
Network connection refers to storing data on the cloud. HTTP or FTP file and content transfers through the java.net.* packages makes this happen.
SharedPreferences is mainly for application-specific settings that you can access via your Settings menu - like application settings. It's a good idea to keep everything simple here - mostly boolean flags, short strings, or integers. SharedPreferences data persist on device reboot, and are removed along with app uninstallation. Data is saved as a key-value pair.
Internal Storage is mostly used for larger non-persistent data storage. You utilize internal storage if you want to process an image, a short video clip, a large text file, etc. But you don't store the processed data in the internal storage - its function is more like a CPU's RAM. The amount of available internal storage for your application depends on the device, but it's always a good idea to keep anything under 1MB. Data is referenced via its file path.
External Storage does not only refer to the SDCard storage, but for higher-end phones, this can mean internal mountable storage (like in the Galaxy Nexus or S2). This is where you store the large video files, the high-resolution images, and the 20-megabyte text file you want to parse in your application. This is also a place to store data that you want shared across devices if you swap sd cards. Data is also referenced via its file path.
SQLite Databases is where you'd store pretty much anything you want in a regular database - with the advantage of organizing things into tables, rows, and columns. It works best with things that you want displayed in the UI as lists - the best example would be the great invention knows as the CursorAdapter. Data stored here also persist on device reboot, and are removed with app uninstallation. You can also share data across applications with sqlite db if you hook it up to a ContentProvider. Data is accessed using a Cursor, where you can call methods as if you're executing sql statements.
Network Connection is not really a data storage technique, but can be a way of persisting data for a specific user provided the device is connected to the internet, using some sort of authentication. You have to balance out between downloading data every time the app needs it, or having a one-time data sync, which would ultimately lead to another of the storage options mentioned above.
Shared preferences are key/value pairs, nothing more. So if you want to keep track of say, students and their test score, it really won't work well for that.
A database is just that, a database. You can define as many columns (and tables) as you need to get the job done.
If it's preferences for your app, use shared preferences (almost any preference I can think of can be done that way), if it's anything else more complicated, use a database.
Related
This question already has answers here:
How to save/restore global variables in android even when os kill application
(2 answers)
Closed 5 years ago.
I am facing a problem in y code that I am creating an audio recorder app that saves audio files but for name of the files I am using count variable and initialising it to 0 initially as below
static int count=0;
and then incrementing it for each new recording
but the problem is that till the app is not destroyed count is working fine but after destroying the app when I am again starting the app then count is again initialised with 0 and my previous recordings are overwritten. So how to resolve this issue and make count to increment from where it left off before app was destroyed
You can either use a database (which is probably oversized for your need) or you can persist it as preference(see https://developer.android.com/guide/topics/data/data-storage.html#pref). To save:
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("silentMode", mSilentMode);
// Commit the edits!
editor.commit();
and to read:
// Restore preferences
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
boolean silent = settings.getBoolean("silentMode", false);
setSilent(silent);
Different Storage options in Android
Content Providers
Consider the structured data added to the device from application1 is
not accessible to another application2 present in the same device but
the profile photo added to the device by application1 is available to
the application2 running in the same device
Consider android device as a city, the applications in it are the
houses in the city, people in the houses(application) are the data.
Now content provider is like an broker in the city(android device).
This broker provide access for the people in the city for finding
different houses referring as the content provider in the android
device provide access for the data in the device for different
applications.
Shared Preferences
Consider I have an App say a Face book App which I use to log in to
my account.
Now the very first time I enter my username and password to get
access to my account. Say I log out of the application an hour later
again I use the same Face book App to login again to my application.
I have to enter username and password again to login to my account
and I set a theme to my application and other settings on how my app
looks in my current phone
This is un-necessary because consider I am using my phone to login to
the application. So I will always use my phone to login again and
again, thus entering my credentials again and again is more work
shows it’s not a user friendly app
Shared Preferences is very handy in such scenarios where I can use
its feature to share my data in a xml file Which physically exists in
the Android app installed in my phone which is not destroyed even if
the app is closed. Here we can save user preferences data of the
current application.
As a result next time I open my app in my phone I can see the data
automatically filled in the necessary fields and the settings are
File Storage
In Android we can use the device storage space to store the data in
it for the applications. The type of data involves things such as a
text file, image file, video file, audio file etc.
As seen in the figure as we can see that there are two places we can
do this. One way is to write the raw files into primary /secondary
storage. Another way is to write the cache files into the
primary/secondary storage.
There is also difference between storing raw data and the cache data,
the raw data once stored in memory by user has to be explicitly
deleted by the user explicitly otherwise it would exist till then.
Cache data stored in memory is not a permanent data because the
system automatically deletes it if it feels there is shortage of
memory.
Internal Storage:
Consider a user in an application has stored data in internal
storage, then only that user of that application has access to that
data on the mobile and that data is automatically deleted when the
user uninstalls the application. Speaking of which internal memory is
private.
The apps internal storage directory is stored using the name package
name in a special place in the android file system.
Other apps or users of current app have no access to the file set by
a particular user and a particular app unless it is explicitly made
available to the user for readable/writable access.
SQLite
Sqlite is used to store more structured data locally in a mobile
where the android app is running. Structured data involves as of
which shown in the figure like a student’s information in the form of
rows and columns.
Sqlite offers similar functionality like Mysql and oracle but with
limited functional features. Some of the things involve performing
query operations on tables. There are features though like creating
views but also some features are not available like stored procedure.
Sqlite is very helpful in storing complex and large data which can be
downloaded once and can be used again and again until the application
is running. When the application is closed the sqlite database is
also destroyed.
Putting all the pieces together
Answer credit - Devrath
The android documentation has the following options below but does not explain what circumstances each is best for. What are the pros and cons of each method? e.g. Under what conditions would SQL be better than Shared Preferences?
Shared Preferences
Internal Storage
External Storage
SQLite Databases
Network Connection
Different Storage options in Android
Content Providers
Consider the structured data added to the device from application1 is
not accessible to another application2 present in the same device but
the profile photo added to the device by application1 is available to
the application2 running in the same device
Consider android device as a city, the applications in it are the
houses in the city, people in the houses(application) are the data.
Now content provider is like an broker in the city(android device).
This broker provide access for the people in the city for finding
different houses referring as the content provider in the android
device provide access for the data in the device for different
applications.
Shared Preferences
Consider I have an App say a Face book App which I use to log in to
my account.
Now the very first time I enter my username and password to get
access to my account. Say I log out of the application an hour later
again I use the same Face book App to login again to my application.
I have to enter username and password again to login to my account
and I set a theme to my application and other settings on how my app
looks in my current phone
This is un-necessary because consider I am using my phone to login to
the application. So I will always use my phone to login again and
again, thus entering my credentials again and again is more work
shows it’s not a user friendly app
Shared Preferences is very handy in such scenarios where I can use
its feature to share my data in a xml file Which physically exists in
the Android app installed in my phone which is not destroyed even if
the app is closed. Here we can save user preferences data of the
current application.
As a result next time I open my app in my phone I can see the data
automatically filled in the necessary fields and the settings are
File Storage
In Android we can use the device storage space to store the data in
it for the applications. The type of data involves things such as a
text file, image file, video file, audio file etc.
As seen in the figure as we can see that there are two places we can
do this. One way is to write the raw files into primary /secondary
storage. Another way is to write the cache files into the
primary/secondary storage.
There is also difference between storing raw data and the cache data,
the raw data once stored in memory by user has to be explicitly
deleted by the user explicitly otherwise it would exist till then.
Cache data stored in memory is not a permanent data because the
system automatically deletes it if it feels there is shortage of
memory.
Internal Storage:
Consider a user in an application has stored data in internal
storage, then only that user of that application has access to that
data on the mobile and that data is automatically deleted when the
user uninstalls the application. Speaking of which internal memory is
private.
The apps internal storage directory is stored using the name package
name in a special place in the android file system.
Other apps or users of current app have no access to the file set by
a particular user and a particular app unless it is explicitly made
available to the user for readable/writable access.
SQLite
Sqlite is used to store more structured data locally in a mobile
where the android app is running. Structured data involves as of
which shown in the figure like a student’s information in the form of
rows and columns.
Sqlite offers similar functionality like Mysql and oracle but with
limited functional features. Some of the things involve performing
query operations on tables. There are features though like creating
views but also some features are not available like stored procedure.
Sqlite is very helpful in storing complex and large data which can be
downloaded once and can be used again and again until the application
is running. When the application is closed the sqlite database is
also destroyed.
Putting all the pieces together
Shared preferences are good for storing ... an application's preferences, and other small bits of data. It's a just really simple persistent string key store for a few data types: boolean, float, int, long and string. So for instance if my app had a login, I might consider storing the session key as string within SharedPreferences.
Internal storage is good for storing application data that the user doesn't need access to, because the user cannot easily access internal storage. Possibly good for caching, logs, other things. Anything that only the app intends to Create Read Update or Delete.
External storage. Great for the opposite of what I just said. The dropbox app probably uses external storage to store the user's dropbox folder, so that the user has easy access to these files outside the dropbox application, for instance, using the file manager.
SQLite databases are great whenever you are going to use a lot of structured data and a relatively rigid schema for managing it. Put in layman's terms, SQLite is like MySQL or PostgreSQL except instead of the database acting as a server daemon which then takes queries from the CGI scripts like php, it is simply stored in a .db file, and accessed and queried through a simple library within the application. While SQLite cannot scale nearly as big as the dedicated databases, it is very quick and convenient for smaller applications, like Android apps. I would use an SQLite db if I were making an app for aggregating and downloading recipes, since that kind of data is relatively structured and a database would allow for it to scale well. Databases are nice because writing all of your data to a file, then parsing it back in your own proprietary format it no fun. Then again, storing data in XML or JSON wouldn't be so bad.
Network connection refers to storing data on the cloud. HTTP or FTP file and content transfers through the java.net.* packages makes this happen.
SharedPreferences is mainly for application-specific settings that you can access via your Settings menu - like application settings. It's a good idea to keep everything simple here - mostly boolean flags, short strings, or integers. SharedPreferences data persist on device reboot, and are removed along with app uninstallation. Data is saved as a key-value pair.
Internal Storage is mostly used for larger non-persistent data storage. You utilize internal storage if you want to process an image, a short video clip, a large text file, etc. But you don't store the processed data in the internal storage - its function is more like a CPU's RAM. The amount of available internal storage for your application depends on the device, but it's always a good idea to keep anything under 1MB. Data is referenced via its file path.
External Storage does not only refer to the SDCard storage, but for higher-end phones, this can mean internal mountable storage (like in the Galaxy Nexus or S2). This is where you store the large video files, the high-resolution images, and the 20-megabyte text file you want to parse in your application. This is also a place to store data that you want shared across devices if you swap sd cards. Data is also referenced via its file path.
SQLite Databases is where you'd store pretty much anything you want in a regular database - with the advantage of organizing things into tables, rows, and columns. It works best with things that you want displayed in the UI as lists - the best example would be the great invention knows as the CursorAdapter. Data stored here also persist on device reboot, and are removed with app uninstallation. You can also share data across applications with sqlite db if you hook it up to a ContentProvider. Data is accessed using a Cursor, where you can call methods as if you're executing sql statements.
Network Connection is not really a data storage technique, but can be a way of persisting data for a specific user provided the device is connected to the internet, using some sort of authentication. You have to balance out between downloading data every time the app needs it, or having a one-time data sync, which would ultimately lead to another of the storage options mentioned above.
Shared preferences are key/value pairs, nothing more. So if you want to keep track of say, students and their test score, it really won't work well for that.
A database is just that, a database. You can define as many columns (and tables) as you need to get the job done.
If it's preferences for your app, use shared preferences (almost any preference I can think of can be done that way), if it's anything else more complicated, use a database.
I have scenario where there are 4 (or more) applications, the first one which runs on a device (it can be any one of the 4 applications) will generate a Unique ID and store it on some where, and all other applications which runs afterwards requires to read Unique ID that was generated by the first running application.
I want to exclude External Storage option as some user may easily change the stored value.
I also considered Shared Preferences, but it seems using Shared Preferences we can implement multiple applications to read the data generated by a single application, but all applications cannot write this shared data.
You can also have the Sqlite DB option and share a ContentProvider for the other applications to be able to access or modify the data. The advantage is that this data will be stored locally, the disadvantage will be that if you want a security for your data you will have to encrypt your data or choose the Remote Server option.
I'm making a simple GPA android app. The user can input their grades and class names for each semester. How would I then store each of these semesters so that they can always be pulled up in the app? I might also need to store random variables that are alone.
I've briefly looked at options such as Shared Preferences, Internal Storage, and others. What option is the best for my needs? Please explain why. Thanks!
Here is Explanation...
Shared preferences are good for storing ... an application's preferences, and other small bits of data. It's a just really simple persistent string key store for a few data types: boolean, float, int, long and string. So for instance if my app had a login, I might consider storing the session key as string within SharedPreferences.
Internal storage is good for storing application data that the user doesn't need access to, because the user cannot easily access internal storage. Possibly good for caching, logs, other things. Anything that only the app intends to Create Read Update or Delete.
External storage. Great for the opposite of what I just said. The dropbox app probably uses external storage to store the user's dropbox folder, so that the user has easy access to these files outside the dropbox application, for instance, using the file manager.
SQLite databases are great whenever you a lot of structured data and a relatively rigid schema for managing it. Put in layman's terms, SQLite is like MySQL or PostgreSQL except instead of the database acting as a server daemon which then takes queries from the CGI scripts like php, it is simply stored in a .db file, and accessed and queried through a simple library within the application. While SQLite cannot scale nearly as big as the dedicated databases, it is very quick and convenient for smaller applications, like Android apps. I would use an SQLite db if I were making an app for aggregating and downloading recipes, since that kind of data is relatively structured and a database would allow for it to scale well. Databases are nice because writing all of your data to a file, then parsing it back in your own proprietary format it no fun. Then again, storing data in XML or JSON wouldn't be so bad.
Network connection refers to storing data on the cloud. HTTP or FTP file and content transfers through the java.net.* packages makes this happen.
Considering this i suggest you to use Sqlite especially in your case.
Best luck
it depends on your need, some times you use all options in the same app,
for example : the best way to store grades and classes is using database, in android SqlLite database.
and for storing some variables values like username and password you just need to use shared preferences.... at least this is my policy in my apps.
SQLite will be the best for your scenario.
As you can create well formatted Tables with desired columns. Either you can use pre-developed database or you can create tables on the go.
I am looking to store simple variables so that if the app process is stopped the data will still be available when it relaunches. I looked into extending the Application class and sharedPreferences. To me, it seems that extending Application is good for temporary global variables that are deleted when the app process is stopped. sharedPreferences however saves the variable onto a file so that is is always available. What are the differences between the two, and what are their optimal uses? Also, what is the best for storing variables that you want to keep even if the app is stopped?
When your app's process is killed, any data stored in the Application class will be lost. You should only use that for storing data that is not needed across multiple launches and uses of your app.
For storing simple data like highscores, sound preference, showing a dialog at startup preference, your best bet would be SharedPreferences. For more comprehensive data, like a list of purchases made by an user in your app, or notes in a todo list app, you should use an SQLite Database.
Beyond that, if you want to store files like PDFs etc. or images (images can also be saved into a database), you can use the internal storage or the external storage (may be an SD Card, or a partition on the internal storage). Please keep in mind that on most devices, internal storage is very limited and you shouldn't save excessively large file there.
This part of the documentation should help you with storage options.