Accessing the Existing sqlite database from assets

Question

In my project I need to add data which gets stored on to database and retrieves data when asked to display.

I created a database called DannyZ with a table in it using SQLite browser in my computer and stored it in the assets folder of my android application project.

Then i added a class DatabaseHelper.java. I get the filenotfound exception in the code.I quit couldnot figure out, is the database file being recognised or not.

The below is the code for DatabaseHelper class.

    public class DatabaseHelper extends SQLiteOpenHelper 
{
    private static String DB_PATH = "/data/data/pack.dannyzdatabase/databases/";
    private static String DB_NAME = "DannyZ";
    private SQLiteDatabase myDatabase;
    private final Context myContext;

    /**
     * Constructor
     * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
     * @param context
     */

    public DatabaseHelper(Context context){

        super(context,DB_NAME,null,1);
        this.myContext = context;
    }
    /** creates an empty database on the system and rewrites it **/
    public void createDatabase() throws IOException {
    boolean dbExist = checkDatabase();
    if(dbExist){
        //do nothing - database already exists
        }else{
        this.getReadableDatabase();
        try {
            copyDatabase();
        } catch(IOException e){
            throw new Error ("Error copying Database");
        }
        }
        }   

        private boolean checkDatabase(){
    SQLiteDatabase checkDB = null;
    try{
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READONLY);
    } catch(SQLiteException e){
    }
    if(checkDB!= null){
        checkDB.close();
    }
    return checkDB!= null? true : false;
    }

    /*** 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 database as input stream
    InputStream myInput = myContext.getAssets().open(DB_NAME);

    //path to the just created empty database
    String outFileName = DB_PATH + DB_NAME;

    //Open the empty database 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))>0)
        myOutput.write(buffer,0,length);
    myOutput.flush();
    myOutput.close();
    myInput.close();
    }
    //close the streams
    public void openDatabase() throws SQLException {
    String myPath = DB_PATH + DB_NAME;
    myDatabase = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READONLY);
    }
    @Override
    public synchronized void close() {
    if(myDatabase != null)
    myDatabase.close();
    super.close();}
    @Override
    public void onCreate(SQLiteDatabase db) {
    db.execSQL(null);
    onCreate(db);
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS");
    onCreate(db);
    }
    }

Sorry for my poor formatting,I am new to stack overflow.

please help me!!

Answer 1

I had same issue earlier and I created a DatabaseHelper class to handle all the Sqlite operations.

Here is the example:

public class DataBaseHelper extends SQLiteOpenHelper {
    private Context context;

    //add the database file into assets folder of your project, what you have created using SqliteBrowser
    //make sure give proper extension
    private static String DB_NAME = "(your_datbase_file_name).sqlite";//the extension can be .sqlite or .db
    public SQLiteDatabase myDataBase;


    public DataBaseHelper(Context context) throws IOException {
        super(context,DB_NAME,null,1);
        this.context=context;
        boolean dbexist = checkdatabase();
        if (dbexist) {
            //If the database exists, open it
            opendatabase(); 
        } else {
            //else create new database
            createdatabase();
        }
    }

    public void createdatabase() throws IOException {

            this.getReadableDatabase();
            try {
                copydatabase();
            } catch(IOException e) {
                throw new Error("Error copying database");
            }
    }   

    private boolean checkdatabase() {

        boolean checkdb = false;
        try {
            String myPath = DB_PATH + DB_NAME;
            File dbfile = new File(myPath);
            checkdb = dbfile.exists();
        } catch(SQLiteException e) {
            System.out.println("Database doesn't exist");
        }
        return checkdb;
    }

    private void copydatabase() throws IOException {
        //Open your local db as the input stream
        InputStream myinput = context.getAssets().open(DB_NAME);

        // Path to the just created empty db
        String outfilename = DB_PATH + DB_NAME;

        //Open the empty db as the output stream
        OutputStream myoutput = new FileOutputStream("/data/data/(your_project_package_name)/databases/(your_datbase_name).sqlite");

        // transfer byte to inputfile to outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myinput.read(buffer))>0) {
            myoutput.write(buffer,0,length);
        }

        //now clear and close the streams
        myoutput.flush();
        myoutput.close();
        myinput.close();
    }

    public void opendatabase() throws SQLException {
        //Open the database
        String mypath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(mypath, null, SQLiteDatabase.OPEN_READWRITE);
    }

    public synchronized void close() {
        if(myDataBase != null) {
            myDataBase.close();
        }
        super.close();
    }

}

Deep Thanks to Jaydeep Khamar for helping in this.

Answer 2

Try this:

File file = new File(outFileName);

if (!file.exist()) file.mkdir();

I assume that the path you are trying to copy your database is not existed.. that is why it gave you the error.