android - Getting a prepopulated database located in the Assets folder into the data/data/mypackage/databases

Question

I have been trying to follow the example: http://blog.softeq.com/2012/12/using-pre-populated-sqlite-database-in.html

This example is supposed to show you how to open a prepopulated database stored in the Assets folder.

There have been threads created related to this topic and I have tried the suggestions made, but its not helping me to figure out why the program doesn't open the database file. What am I doing wrong? Here is what I'm getting in the first few lines of LogCat:

01-13 15:54:33.171: E/Trace(30747): error opening trace file: No such file or directory (2)
01-13 15:54:33.171: D/ActivityThread(30747): setTargetHeapUtilization:0.25
01-13 15:54:33.171: D/ActivityThread(30747): setTargetHeapIdealFree:8388608
01-13 15:54:33.171: D/ActivityThread(30747): setTargetHeapConcurrentStart:2097152
01-13 15:54:33.251: D/AbsListView(30747): Get MotionRecognitionManager
01-13 15:54:33.261: E/SQLiteLog(30747): (14) cannot open file at line 30245 of [00bb9c9ce4]
01-13 15:54:33.261: E/SQLiteLog(30747): (14) os_unix.c:30245: (2) open(/data/data/com.example.prepopdb/databases/yourdb.db) - 
01-13 15:54:33.261: E/SQLiteDatabase(30747): Failed to open database '/data/data/com.example.prepopdb/databases/yourdb.db'.
01-13 15:54:33.261: E/SQLiteDatabase(30747): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:278)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:217)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:464)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:186)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:178)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at com.example.prepopdb.ExternalDbOpenHelper.checkDataBase(ExternalDbOpenHelper.java:62)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at com.example.prepopdb.ExternalDbOpenHelper.createDataBase(ExternalDbOpenHelper.java:43)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at com.example.prepopdb.ExternalDbOpenHelper.openDataBase(ExternalDbOpenHelper.java:97)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at com.example.prepopdb.ExternalDbOpenHelper.<init>(ExternalDbOpenHelper.java:37)
01-13 15:54:33.261: E/SQLiteDatabase(30747):    at com.example.prepopdb.PrepopSqliteDbActivity.onCreate(PrepopSqliteDbActivity.java:35)

I created the test database with SQLite Database Browser as mentioned in the above link with the exception of my database extension being ".db" instead of ".sqlite3". (Though I have tried using ".sqlite3" as well, with similar/same errors).

Here is the code for my PrepopSqliteDbActivity:

package com.example.prepopdb;

import com.example.prepopdb.ExternalDbOpenHelper;
import java.util.ArrayList;

import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class PrepopSqliteDbActivity extends ListActivity {

private static final String DB_NAME = "yourdb.db";

// Database field names
private static final String TABLE_NAME = "friends";
private static final String FRIEND_ID = "_id";
private static final String FRIEND_NAME = "name";

private SQLiteDatabase database;
private ListView listView;
private ArrayList<String> friends;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ExternalDbOpenHelper dbOpenHelper = new ExternalDbOpenHelper(this,
            DB_NAME);
    database = dbOpenHelper.openDataBase(); // Database is open

    /*SOME OTHER CODE HERE*/
}

Here is the code for my ExternalDbOpenHelper:

package com.example.prepopdb;

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.os.Environment;
import android.util.Log;

public class ExternalDbOpenHelper extends SQLiteOpenHelper {

// Path to the device folder with database
public static String DB_PATH;

// Database filename
public static String DB_NAME;
public SQLiteDatabase database;
public final Context context;

public SQLiteDatabase getDb() {
    return database;
}

public ExternalDbOpenHelper(Context context, String databaseName) {
    super(context, databaseName, null, 1);
    this.context = context;

    // Write the full path to the databases of your application
    String packageName = context.getPackageName();
    DB_PATH = String.format("%s/data/%s/databases/", Environment.getDataDirectory(), packageName);
    DB_NAME = databaseName;
    openDataBase();

}

// Create a database if its not yet created
public void createDataBase() {
    boolean dbExist = checkDataBase();
    if (!dbExist) {
        this.getReadableDatabase();
        try {
            copyDataBase();
        } catch (IOException e) {
            Log.e(this.getClass().toString(), "Copying error!");
            throw new Error("Error copying database!");
        }
    } else {
        Log.i(this.getClass().toString(), "Database already exists");
    }
}

//Performing a database existence check
private boolean checkDataBase(){
    SQLiteDatabase checkDb = null;
    try {
        String path = DB_PATH + DB_NAME;
        checkDb = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READONLY);
    } catch (SQLException e){
        Log.e(this.getClass().toString(), "Error while checking db");
    }

    if (checkDb != null){
        checkDb.close();
    }
    return checkDb !=null;
}

private void copyDataBase() throws IOException {
    //Open a stream for reading, located in the assets
    InputStream externalDbStream = context.getAssets().open(DB_NAME);
    //Path to the created empty database on your Android device
    String outFileName = DB_PATH + DB_NAME;

    //Create a stream for writing the database byte by byte
    OutputStream localDbStream = new FileOutputStream(outFileName);

    //Copy the database
    byte[] buffer = new byte[1024];
    int bytesRead;
    while((bytesRead = externalDbStream.read(buffer)) > 0){
        localDbStream.write(buffer, 0, bytesRead);
    }

    //Close the streams
    localDbStream.close();
    externalDbStream.close();
}

SQLiteDatabase openDataBase() throws SQLException {
    String path = DB_PATH + DB_NAME;
    if (database == null) {
        createDataBase();
        database = SQLiteDatabase.openDatabase(path, null,
                SQLiteDatabase.OPEN_READWRITE);
        //database = getWritableDatabase();
    }
    return database;
}

@Override
public synchronized void close(){
    if (database != null){
        database.close();
    }
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}
}

UPDATE

Thank you Carlos. I agree its not a good idea to hardcode the path as it might be different device to device. I made the changes as you suggested, however I'm still getting the same error. I've verified that the yourdb.db file has read/write permissions for all levels.

I mentioned this in a previous comment, but could any of this be happening because I'm using a non-rooted phone? Could the permission of "yourdb.db" possibly change after copying it from the Asssets folder into /data/data/com.example.prepopdb/databases/ and then my program attempting to open it? I know how to change the permission using adb, but how do go about doing this from within the program?

Here's what my Logcat says:

01-14 12:18:02.240: E/Trace(18167): error opening trace file: No such file or directory (2)
01-14 12:18:02.240: D/ActivityThread(18167): setTargetHeapUtilization:0.25
01-14 12:18:02.240: D/ActivityThread(18167): setTargetHeapIdealFree:8388608
01-14 12:18:02.240: D/ActivityThread(18167): setTargetHeapConcurrentStart:2097152
01-14 12:18:02.360: D/AbsListView(18167): Get MotionRecognitionManager
01-14 12:18:02.370: E/SQLiteLog(18167): (14) cannot open file at line 30245 of [00bb9c9ce4]
01-14 12:18:02.370: E/SQLiteLog(18167): (14) os_unix.c:30245: (2) open(/data/data/com.example.prepopdb/databases/yourdb.db) - 
01-14 12:18:02.370: E/SQLiteDatabase(18167): Failed to open database '/data/data/com.example.prepopdb/databases/yourdb.db'.
01-14 12:18:02.370: E/SQLiteDatabase(18167): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:278)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:217)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:464)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:186)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:178)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at com.example.prepopdb.ExternalDbOpenHelper.checkDataBase(ExternalDbOpenHelper.java:63)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at com.example.prepopdb.ExternalDbOpenHelper.createDataBase(ExternalDbOpenHelper.java:45)
01-14 12:18:02.370: E/SQLiteDatabase(18167):    at com.example.prepo

Answer 1

You are assuming too much about the data folder. You rather should let the system give you the correct path. You can get database path with context.getDatabasePath(); you pass the desired name to the file (no matter if it exists or not). And actually you are supposed to do it that way

For that, at any place you are using something like String outFileName = DB_PATH + DB_NAME; you should change it for

 String outFileName =myContext.getDatabasePath(DB_NAME).getPath() ;

and that's the real valid location for your file. So wour helper will be like this

public class ExternalDbOpenHelper extends SQLiteOpenHelper {

// Path to the device folder with database
public static String DB_PATH;

// Database filename
public static String DB_NAME;
public SQLiteDatabase database;
public final Context context;

public SQLiteDatabase getDb() {
    return database;
}

public ExternalDbOpenHelper(Context context, String databaseName) {
    super(context, databaseName, null, 1);
    this.context = context;
        DB_NAME = databaseName;
            DB_PATH =context.getDatabasePath(DB_NAME).getPath() ;
    openDataBase();

}

// Create a database if its not yet created
public void createDataBase() {
    boolean dbExist = checkDataBase();
    if (!dbExist) {
        this.getReadableDatabase();
        try {
            copyDataBase();
        } catch (IOException e) {
            Log.e(this.getClass().toString(), "Copying error!");
            throw new Error("Error copying database!");
        }
    } else {
        Log.i(this.getClass().toString(), "Database already exists");
    }
}

//Performing a database existence check
private boolean checkDataBase(){
    SQLiteDatabase checkDb = null;
    try {

        checkDb = SQLiteDatabase.openDatabase(DB_PATH, null, SQLiteDatabase.OPEN_READONLY);
    } catch (SQLException e){
        Log.e(this.getClass().toString(), "Error while checking db");
    }

    if (checkDb != null){
        checkDb.close();
    }
    return checkDb !=null;
}

private void copyDataBase() throws IOException {
    //Open a stream for reading, located in the assets
    InputStream externalDbStream = context.getAssets().open(DB_NAME);



    //Create a stream for writing the database byte by byte
    OutputStream localDbStream = new FileOutputStream(DB_PATH);

    //Copy the database
    byte[] buffer = new byte[1024];
    int bytesRead;
    while((bytesRead = externalDbStream.read(buffer)) > 0){
        localDbStream.write(buffer, 0, bytesRead);
    }

             //FLUSH THE OUT STREAM
             localDbStream.flush();

    //Close the streams
    localDbStream.close();
    externalDbStream.close();
}

SQLiteDatabase openDataBase() throws SQLException {

    if (database == null) {
        createDataBase();
        database = SQLiteDatabase.openDatabase(DB_PATH, null,
                SQLiteDatabase.OPEN_READWRITE);
        //database = getWritableDatabase();
    }
    return database;
}

@Override
public synchronized void close(){
    if (database != null){
        database.close();
    }
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}
}

with this it should work

UPDATE

Yo can take a few of considerations:

• take a look at what path is the system returning for your database

  DB_PATH =context.getDatabasePath(DB_NAME).getPath() ;
  Log.i ("myApp", DB_PATH);
  

• check the code in the emulator, to see if you have the same problems. there you can manually check if the file is actually created, as explained here

• add permissions to write and read the sdcard (READ_EXTERNAL_STORAGE and WRITE_EXTERNAL_STORAGE). but i dont actually believe you need this