sqlite - Android - Could not open database -

i have db.sqlite file in asset folder , error when try open it:

android.database.sqlite.sqlitecantopendatabaseexception: unknown error (code 14): not open database

i've tried different paths , names (with , without extension) can't make work.

package com.example.app.db;  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.sqliteexception; import android.database.sqlite.sqliteopenhelper; import android.widget.toast;  public class databasehelper extends sqliteopenhelper {  // android's default system path of application database. private static string db_path = "/data/data/com.example.app/databases/"; private static string db_name = "app"; private sqlitedatabase mydatabase; private final context mycontext;  /**  * constructor takes , keeps reference of passed context in order  * access application assets , resources.  *   * @param context  */ public databasehelper(context context) {     super(context, db_name, null, 1);     this.mycontext = context; }  /**  * creates empty database on system , rewrites own  * database.  * */ public void createdatabase() throws ioexception {     boolean dbexist = checkdatabase();      if (dbexist) {         // nothing - database exist     } else {          // calling method , empty database created         // default system path         // of application gonna able overwrite         // database our database.         this.getreadabledatabase();         try {             copydatabase();         } catch (ioexception e) {             throw new error("error copying database");         }     } }  /**  * check if database exist avoid re-copying file each  * time open application.  *   * @return true if exists, false if doesn't  */  private boolean checkdatabase(){         boolean checkdb = false;         try{             string mypath = mycontext.getfilesdir().getabsolutepath().replace("files", "databases")+file.separator + db_name;             file dbfile = new file(mypath);                             checkdb = dbfile.exists();         }         catch(sqliteexception e){             system.out.println("database doesn't exist");         }          return checkdb;     }  /**  * copies database local assets-folder created  * empty database in system folder, can accessed ,  * handled. done transfering bytestream.  * */ private void copydatabase() throws ioexception {      // open local db input stream     inputstream myinput = mycontext.getassets().open(db_name);      // path created empty db     string outfilename = db_path + db_name;      // open empty db output stream     outputstream myoutput = new fileoutputstream(outfilename);      // transfer bytes inputfile outputfile     byte[] buffer = new byte[1024];     int length;     while ((length = myinput.read(buffer)) > 0) {         myoutput.write(buffer, 0, length);     }      // close streams     myoutput.flush();     myoutput.close();     myinput.close(); }   public void opendatabase() throws sqlexception{      //open 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) {  } } 

i error when try open here:

package com.example.app;  import android.app.activity; import android.os.bundle; import android.widget.textview; import com.example.app.db.databasehelper;   public class speakerslistactivity extends activity {  public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.mylayout);            databasehelper dbhelper = new databasehelper(this);     dbhelper.opendatabase(); } } 

you need check existence of database file first not doing here

databasehelper dbhelper = new databasehelper(this); dbhelper.opendatabase(); 

you making object of databasehelper , calling .opendatabase()

try constructor :

public databasehelper(context context) {     super(context, db_name, null, 1);    this.mycontext = context;    try{         string mypath = db_path + db_name; // check extension of db file          file dbfile = new file(mypath);                             if( dbfile.exists());              toast.maketext(context, "database exists", toast.length_long).show();             else              toast.maketext(context, "cant find database", toast.length_long).show();         }         catch(sqliteexception e){             system.out.println("database doesn't exist");         }  }