Question

I use this tutorial:
Tutorial Custom database

I copy database from assets folder and copy it to my device(or emulator). Everything is correct. I see my database in DDMS perspective. But I want aslo upgrade my database sometimes so i did:

super(context, DB_NAME, null, 2); //changed version from 1 to 2

and modify onUpgrade method:

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    if(newVersion > oldVersion){
        this.myContext.deleteDatabase(DB_NAME);
        try {
            this.copyDataBase();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

But after run I have still old version of database on my device. How I can delete old version of database and copy new. DB_NAME is my database name(with format, but not path) and copyDataBase() is method that copy database to device(and it’s work).

I paste my all code:

public class DataBaseHelper extends SQLiteOpenHelper{

    private static String DB_PATH = "/data/data/sitcom.quiz/databases/";

    private static String DB_NAME = "sitcoms.sqlite";

    private SQLiteDatabase myDataBase; 

    private final Context myContext;

    public DataBaseHelper(Context context) {

        super(context, DB_NAME, null, 4);
        this.myContext = context;
    }   

    public void createDataBase() throws IOException{

        boolean dbExist = checkDataBase();

        if(dbExist){
            //do nothing - database already exist
        }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){
            //database does't exist yet.
        }

        if(checkDB != null){
            checkDB.close();
        }

        return checkDB != null ? true : false;
    }


    private void copyDataBase() throws IOException{

        //Open your local db as the input stream
        InputStream myInput = myContext.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(outFileName);

        //transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer))>0){
            myOutput.write(buffer, 0, length);
        }

        //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_READONLY);

    }

    @Override
    public synchronized void close() {

            if(myDataBase != null)
                myDataBase.close();

            super.close();

    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.d("adas", "dasd");

        if(newVersion > oldVersion){
            String myPath = DB_PATH + DB_NAME;
            this.myContext.deleteDatabase(myPath);
            try {
                this.copyDataBase();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


}

and my activity:

DataBaseHelper myDbHelper = new DataBaseHelper(this);
        myDbHelper = new DataBaseHelper(this);

        try {
            myDbHelper.createDataBase();
        } catch (IOException ioe) {
            throw new Error("Unable to create database");
        }
        try {
            myDbHelper.openDataBase();
        }catch(SQLException sqle){
            throw sqle;
        }

Thanks if you can give me reason or only hint why this don’ t work.

Answer 1

android already opened the db when the function onUpgrade() is called. i don’t think it is possible to delete it at this time. check the log for more info. if you wanna do it this way, you need to move the delete and copy code to a place where the db is not open yet.