How to save data in an android app

Question

I recently coded an Android app  It s just a simple app that allows you to keep score of a basketball game with a few simple counter intervals  I m getting demand to add a save feature  so you can save your scores and then load them back up   Currently  when you stop the app  your data is lost   So what I was wondering is what I would have to add to have the app save a label  score  and then load it back up   Thanks guys sorry I don t know much about this stuff

User · Answer

In my opinion db4o is the easiest way to go. Here you can find a tutorial: http://community.versant.com/documentation/reference/db4o-7.12/java/tutorial/

And here you can download the library:

http://www.db4o.com/community/download.aspx?file=db4o-8.0-java.zip

(Just put the db4o-8.0...-all-java5.jar in the lib directory into your project's libs folder. If there is no libs folder in you project create it)

As db4o is a object oriented database system you can directly save you objects into the database and later get them back.

User · Answer

Quick answer   public class MainActivity extends AppCompatActivity implements View OnClickListener        Boolean Music       public static final String PREFS NAME    MyPrefsFile         Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main              restore preferences         SharedPreferences settings   this getSharedPreferences PREFS NAME  0           Music   settings getBoolean  key   true               Override     public void onClick                        save music setup to system                 SharedPreferences settings   this getSharedPreferences PREFS NAME  0                   SharedPreferences Editor editor   settings edit                    editor putBoolean  key   Music                   editor apply

User · Answer

In onCreate   SharedPreferences sharedPref   getSharedPreferences  mySettings   MODE PRIVATE        String mySetting   sharedPref getString  mySetting   null     In onDestroy or equivalent   SharedPreferences sharedPref   getSharedPreferences  mySettings   MODE PRIVATE        SharedPreferences Editor editor   sharedPref edit        editor putString  mySetting    Hello Android        editor commit

User · Answer

There is a lot of options to store your data and Android offers you to chose anyone Your data storage options are the following   Shared Preferences Store private primitive data in key-value pairs  Internal Storage Store private data on the device memory  External Storage Store public data on the shared external storage  SQLite Databases Store structured data in a private database  Network Connection Store data on the web with your own network server  Check here for examples and tuto

User · Answer

Please don t forget one thing - Internal Storage data are deleted when you uninstall the app  In some cases it can be  unexpected feature   Then it s good to use external storage   Google docs about storage - Please look in particular at getExternalStoragePublicDirectory

User · Answer

Shared preferences  android shared preferences example for high scores  Does your application has an access to the  external Storage Media   If it does then you can simply write the value  store it with timestamp  in a file and save it  The timestamp will help you in showing progress if thats what you are looking for   not a smart solution

User · Answer

You have two options  and I ll leave selection up to you    Shared Preferences  This is a framework unique to Android that allows you to store primitive values  such as int  boolean  and String  although strictly speaking String isn t a primitive  in a key-value framework  This means that you give a value a name  say   homeScore  and store the value to this key   SharedPreferences settings   getApplicationContext   getSharedPreferences PREFS NAME  0   SharedPreferences Editor editor   settings edit    editor putInt  homeScore   YOUR HOME SCORE       Apply the edits  editor apply        Get from the SharedPreferences SharedPreferences settings   getApplicationContext   getSharedPreferences PREFS NAME  0   int homeScore   settings getInt  homeScore   0    Internal Storage  This  in my opinion  is what you might be looking for  You can store anything you want to a file  so this gives you more flexibility  However  the process can be trickier because everything will be stored as bytes  and that means you have to be careful to keep your read and write processes working together   int homeScore  byte   homeScoreBytes   homeScoreBytes 0     byte  homeScore  homeScoreBytes 1     byte   homeScore  gt  gt  8      you can probably skip these two  homeScoreBytes 2     byte   homeScore  gt  gt  16     lines  because I ve never seen a                                                                    basketball score above 128  it s                                                 such a rare occurance   FileOutputStream outputStream   getApplicationContext   openFileOutput FILENAME  Context MODE PRIVATE   outputStream write homeScoreBytes   outputStream close       Now  you can also look into External Storage  but I don t recommend that in this particular case  because the external storage might not be there later   Note that if you pick this  it requires a permission

User · Answer

OP is asking for a  save  function  which is more than just preserving data across executions of the program  which you must do for the app to be worth anything    I recommend saving the data in a file on the sdcard which allows you to not only recall it later  but allows the user to mount the device as an external drive on their own computer and grab the data for use in other places   So you really need a multi-point system   1  Implement onSaveInstanceState    In this method  you re passed a Bundle  which is basically like a dictionary   Store as much information in the bundle as would be needed to restart the app exactly where it left off   In your onCreate   method  check for the passed-in bundle to be non-null  and if so  restore the state from the bundle   2  Implement onPause     In this method  create a SharedPreferences editor and use it to save whatever state you need to start the app up next time  This mainly consists of the users  preferences  hence the name   but anything else relavent to the app s start-up state should go here as well   I would not store scores here  just the stuff you need to restart the app   Then  in onCreate    whenever there s no bundle object  use the SharedPreferences interface to recall those settings   3a  As for things like scores  you could follow Mathias s advice above and store the scores in the directory returned in getFilesDir    using openFileOutput    etc  I think this directory is private to the app and lives in main storage  meaning that other apps and the user would not be able to access the data   If that s ok with you  then this is probably the way to go   3b  If you do want other apps or the user to have direct access to the data  or if the data is going to be very large  then the sdcard is the way to go   Pick a directory name like com user1446371 basketballapp  to avoid collisions with other applications  unless you re sure that your app name is reasonably unique  and create that directory on the sdcard   As Mathias pointed out  you should first confirm that the sdcard is mounted   File sdcard   Environment getExternalStorageDirectory    if  sdcard    null     sdcard isDirectory          fail  sdcard not available      File datadir   new File sdcard   com user1446371 basketballapp     if   datadir exists    amp  amp   datadir mkdirs           fail  unable to create data directory      if   datadir isDirectory           fail  exists  but is not a directory         Now use regular java I O to read and write files to data directory   I recommend simple CSV files for your data  so that other applications can read them easily   Obviously  you ll have to write activities that allow  save  and  open  dialogs   I generally just make calls to the openintents file manager and let it do the work  This requires that your users install the openintents file manager to make use of these features  however

User · Answer

use this methods to use sharedPreferences very easily   private val sharedPreferences   context getSharedPreferences  myPreferences   Context MODE PRIVATE   fun put key  String  value  String    sharedPreferences edit   putString key  value  apply    fun put key  String  value  Int    sharedPreferences edit   putInt key  value  apply    fun put key  String  value  Float    sharedPreferences edit   putFloat key  value  apply    fun put key  String  value  Boolean    sharedPreferences edit   putBoolean key  value  apply    fun put key  String  value  Long    sharedPreferences edit   putLong key  value  apply    fun getString key  String  defaultValue  String    null   String    sharedPreferences getString key  defaultValue   fun getInt key  String  defaultValue  Int   -1   Int   sharedPreferences getInt key  defaultValue   fun getFloat key  String  defaultValue  Float   -1F   Float   sharedPreferences getFloat key  defaultValue   fun getBoolean key  String  defaultValue  Boolean   false   Boolean   sharedPreferences getBoolean key  defaultValue   fun getLong key  String  defaultValue  Long   -1L   Long   sharedPreferences getLong key  defaultValue   fun clearAll     sharedPreferences edit   clear   apply     put them in a class and get context in its constructor

User · Answer

Use SharedPreferences  http   developer android com reference android content SharedPreferences html  Here s a sample  http   developer android com guide topics data data-storage html pref  If the data structure is more complex or the data is large  use an Sqlite database  but for small amount of data and with a very simple data structure  I d say  SharedPrefs will do and a DB might be overhead

[android] How to save data in an android app

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