Can't open database-Android

Question

I'm developing a simple Android application with SQL. I followed the following guides - http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

I get an error when trying to open the database. Here is my DataBaseHelp.Java Class-

public class DataBaseHelper extends SQLiteOpenHelper{

private static String DB_PATH = "/data/data/and.testDB/databases/";

private static String DB_NAME = "MyData";

private SQLiteDatabase myDataBase; 

private final Context myContext;
public DataBaseHelper(Context context) {

 super(context, DB_NAME, null, 1);
    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() {

 //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) {
  }
}

And this is my testDB.Java class-

public class testDB extends Activity {
SQLiteDatabase myDataBase;
public String[] gur = new String[4];
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    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();
// Here is the problem-Can't open the database/
}catch(SQLException sqle){

    throw sqle;

}
    myDataBase = myDbHelper.getWritableDatabase();

    Cursor c = myDataBase.rawQuery("SELECT * FROM beer", null);


if (c != null ) {
    if  (c.moveToFirst()) {
          for(int x=0;x< 1;x++)
          {

              gur[x] = (c.getString(c.getColumnIndex("name")));
              c.moveToNext();
          }
}
    Toast.makeText(this,gur[0],Toast.LENGTH_LONG).show();
}


        }
    }

I created the database using SQLite Database Browser, created a table named "beer", added 2 rows and put it in the /assests folder in my project.

Please note that i'm new to SQL, and its my first time using it. I searched all day for an answer and couldn't find one.

Thanks!

Answer 1

Open your database in sqlite database browser and add a new table called "android_metadata",

you can execute the following SQL statement to do it:

CREATE TABLE "android_metadata" ("locale" TEXT DEFAULT 'en_US')

Now insert a single row with the text 'en_US' in the "android_metadata" table:

INSERT INTO "android_metadata" VALUES ('en_US')

Then, it is necessary to rename the primary id field of your tables to "_id" so Android will know where to bind the id field of your tables.

now copy the new database file into your projects assets folder, it will work.....

Answer 2

You need to create the database in the onCreate method of your database helper (the extension of SQLiteOpenHelper). Your call to getReadableDatabase() won't return anything until a database has been created in the context of the application.

db.execSQL("CREATE TABLE " + TABLE_NAME
+ " (_id INTEGER PRIMARY KEY AUTOINCREMENT,"
+ "foo TEXT, bar TEXT);");

Something along those lines. Obviously fill in your own data scheme.

Then you can read the data from the database you have in your assets folder and insert them into the database using the sqlite commands.

Here's a tutorial that I used to get started:

http://www.devx.com/wireless/Article/40842