How to use an existing database with an Android application

Question

I have already created an SQLite database  I want to use this database file with my Android project  I want to bundle this database with my application    Instead of creating a new database  how can the application gain access to this database and use it as its database

User · Answer

You can do this by using a content provider  Each data item used in the application remains private to the application  If an application want to share data accross applications  there is only technique to achieve this  using a content provider  which provides interface to access that private data

User · Answer

I had trouble with the other DatabaseHelpers regarding this problem  not sure why  This is what worked for me   import java io File  import java io FileOutputStream  import java io IOException  import java io InputStream  import java io OutputStream   import android content Context  import android database sqlite SQLiteDatabase  import android database sqlite SQLiteOpenHelper  import android util Log   public class DatabaseHelper extends SQLiteOpenHelper      private static final String TAG   DatabaseHelper class getSimpleName       private final Context context    private final String assetPath    private final String dbPath     public DatabaseHelper Context context  String dbName  String assetPath        throws IOException       super context  dbName  null  1       this context   context      this assetPath   assetPath      this dbPath     data data             context getApplicationContext   getPackageName       databases             dbName      checkExists                    Checks if the database asset needs to be copied and if so copies it to the      default location              throws IOException         private void checkExists   throws IOException       Log i TAG   checkExists           File dbFile   new File dbPath        if   dbFile exists             Log i TAG   creating database             dbFile getParentFile   mkdirs          copyStream context getAssets   open assetPath   new FileOutputStream            dbFile           Log i TAG  assetPath     has been copied to     dbFile getAbsolutePath                   private void copyStream InputStream is  OutputStream os  throws IOException       byte buf     new byte 1024       int c   0      while  true          c   is read buf         if  c    -1          break        os write buf  0  c             is close        os close            Override   public void onCreate SQLiteDatabase db            Override   public void onUpgrade SQLiteDatabase db  int oldVersion  int newVersion

User · Answer

If you already have a database  keep it in your asset folder and copy it in your application  For more detail  see Android database basics

User · Answer

NOTE  Before trying this code  please find this line in the below code   private static String DB NAME   YourDbName      Database name   DB NAME here is the name of your database  It is assumed that you have a copy of the database in the assets folder  so for example  if your database name is ordersDB  then the value of DB NAME will be ordersDB   private static String DB NAME   ordersDB       Keep the database in assets folder and then follow the below   DataHelper class   import java io File  import java io FileOutputStream  import java io IOException  import java io InputStream  import java io OutputStream   import android content Context  import android database SQLException  import android database sqlite SQLiteDatabase  import android database sqlite SQLiteOpenHelper  import android util Log   public class DataBaseHelper extends SQLiteOpenHelper        private static String TAG    DataBaseHelper      Tag just for the LogCat window     private static String DB NAME   YourDbName      Database name     private static int DB VERSION   1     Database version     private final File DB FILE      private SQLiteDatabase mDataBase      private final Context mContext       public DataBaseHelper Context context            super context  DB NAME  null  DB VERSION           DB FILE   context getDatabasePath DB NAME           this mContext   context             public void createDataBase   throws IOException              If the database does not exist  copy it from the assets          boolean mDataBaseExist   checkDataBase            if  mDataBaseExist                this getReadableDatabase                this close                try                      Copy the database from assests                 copyDataBase                    Log e TAG   createDatabase database created                  catch  IOException mIOException                    throw new Error  ErrorCopyingDataBase                                          Check that the database file exists in databases folder     private boolean checkDataBase             return DB FILE exists                  Copy the database from assets     private void copyDataBase   throws IOException           InputStream mInput   mContext getAssets   open DB NAME           OutputStream mOutput   new FileOutputStream DB FILE           byte   mBuffer   new byte 1024           int mLength          while   mLength   mInput read mBuffer    gt  0                mOutput write mBuffer  0  mLength                     mOutput flush            mOutput close            mInput close                  Open the database  so we can query it     public boolean openDataBase   throws SQLException              Log v  DB PATH   DB FILE getAbsolutePath             mDataBase   SQLiteDatabase openDatabase DB FILE  null  SQLiteDatabase CREATE IF NECESSARY              mDataBase   SQLiteDatabase openDatabase DB FILE  null  SQLiteDatabase NO LOCALIZED COLLATORS           return mDataBase    null              Override     public synchronized void close             if mDataBase    null                mDataBase close                      super close               Write a DataAdapter class like   import java io IOException  import android content Context  import android database Cursor  import android database SQLException  import android database sqlite SQLiteDatabase  import android util Log   public class TestAdapter        protected static final String TAG    DataAdapter        private final Context mContext      private SQLiteDatabase mDb      private DataBaseHelper mDbHelper       public TestAdapter Context context            this mContext   context          mDbHelper   new DataBaseHelper mContext              public TestAdapter createDatabase   throws SQLException           try               mDbHelper createDataBase              catch  IOException mIOException                Log e TAG  mIOException toString        UnableToCreateDatabase                throw new Error  UnableToCreateDatabase                      return this             public TestAdapter open   throws SQLException           try               mDbHelper openDataBase                mDbHelper close                mDb   mDbHelper getReadableDatabase              catch  SQLException mSQLException                Log e TAG   open  gt  gt    mSQLException toString                 throw mSQLException                    return this             public void close             mDbHelper close                public Cursor getTestData              try                String sql   SELECT   FROM myTable                Cursor mCur   mDb rawQuery sql  null                if  mCur    null                    mCur moveToNext                                return mCur             catch  SQLException mSQLException                 Log e TAG   getTestData  gt  gt    mSQLException toString                  throw mSQLException                        Now you can use it like   TestAdapter mDbHelper   new TestAdapter urContext   mDbHelper createDatabase    mDbHelper open     Cursor testdata   mDbHelper getTestData     mDbHelper close      EDIT  Thanks to JDx  For Android nbsp 4 1  Jelly Bean   change   DB PATH     data data     context getPackageName       databases      to   DB PATH   context getApplicationInfo   dataDir     databases      in the DataHelper class  this code will work on Jelly Bean 4 2 multi-users   EDIT  Instead of using hardcoded path  we can use  DB PATH   context getDatabasePath DB NAME  getAbsolutePath      which will give us the full path to the database file and works on all Android versions

User · Answer

If you are having pre built data base than copy it in asset folder and create an new class as DataBaseHelper which implements SQLiteOpenHelper  Than use following code   import java io File  import java io FileOutputStream  import java io IOException  import java io InputStream  import java io OutputStream   import android content Context  import android database Cursor  import android database SQLException  import android database sqlite SQLiteDatabase  import android database sqlite SQLiteOpenHelper   public class DataBaseHelperClass extends SQLiteOpenHelper     The Android s default system path of your application database  private static String DB PATH     data data package name databases       Data Base Name  private static final String DATABASE NAME    DBName sqlite      Data Base Version  private static final int DATABASE VERSION   1     Table Names of Data Base  static final String TABLE Name    tableName    public Context context  static SQLiteDatabase sqliteDataBase          Constructor    Takes and keeps a reference of the passed context in order to access to the application assets and resources      param context    Parameters of super   are    1  Context                                 2  Data Base Name                                  3  Cursor Factory                                  4  Data Base Version      public DataBaseHelperClass Context context               super context  DATABASE NAME  null  DATABASE VERSION       this context   context            Creates a empty database on the system and rewrites it with your own database     By calling this method and empty database will be created into the default system path    of your application so we are gonna be able to overwrite that database with our database        public void createDataBase   throws IOException        check if the database exists     boolean databaseExist   checkDataBase         if databaseExist              Do Nothing       else          this getWritableDatabase                     copyDataBase             end if else dbExist      end createDataBase            Check if the database already exist to avoid re-copying the file each time you open the application      return true if it exists  false if it doesn t     public boolean checkDataBase        File databaseFile   new File DB PATH   DATABASE NAME       return databaseFile exists                      Copies your database from your local assets-folder to the just created empty database in the    system folder  from where it can be accessed and handled     This is done by transferring byte stream        private void copyDataBase   throws IOException         Open your local db as the input stream     InputStream myInput   context getAssets   open DATABASE NAME           Path to the just created empty db     String outFileName   DB PATH   DATABASE NAME         Open the empty db as the output stream     OutputStream myOutput   new FileOutputStream outFileName          transfer bytes from the input file to the output file     byte   buffer   new byte 1024       int length      while   length   myInput read buffer   gt 0           myOutput write buffer  0  length                Close the streams     myOutput flush        myOutput close        myInput close               This method opens the data base connection     First it create the path up till data base of the device     Then create connection with data base      public void openDataBase   throws SQLException              Open the database     String myPath   DB PATH   DATABASE NAME      sqliteDataBase   SQLiteDatabase openDatabase myPath  null  SQLiteDatabase OPEN READWRITE               This Method is used to close the data base connection       Override public synchronized void close          if sqliteDataBase    null          sqliteDataBase close         super close              Apply your methods and class to fetch data using raw or queries on data base using    following demo example code as     public String getUserNameFromDB        String query    select User First Name From   TABLE USER DETAILS      Cursor cursor   sqliteDataBase rawQuery query  null       String userName   null      if cursor getCount   gt 0           if cursor moveToFirst         do                  userName   cursor getString 0                while  cursor moveToNext                         return userName       Override public void onCreate SQLiteDatabase db           No need to write the create table query         As we are using Pre built data base         Which is ReadOnly      Override public void onUpgrade SQLiteDatabase db  int oldVersion  int newVersion           No need to write the update table query         As we are using Pre built data base         Which is ReadOnly         We should not update it as requirements of application           Hope this will help you

[java] How to use an existing database with an Android application

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