SystemDatabaseHelper dbHelper = new SystemDatabaseHelper(this, null, 1);
dbHelper.initialize(this);

public class ContactDBHelper extends SQLiteOpenHelper {

    private ContactDBHelper(Context context, String name,
            CursorFactory factory, int version) {
        super(context, name, factory, version);

    }

    private static ContactDBHelper mInstance;

    public static synchronized ContactDBHelper getInstance() {

        if (mInstance == null) {
            mInstance = new ContactDBHelper(Util.getApplicationContext(),
                    ContactDB.DB_NAME, null, ContactDB.DB_VERSION);
        }
        return mInstance;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(ContactDB.Contact.CREATE_STMT);
        db.execSQL(ContactDB.Contact.CREATE_PHONE_NUMBER_INDEX);
        db.execSQL(ContactDB.Contact.CREATE_REVERSE_PHONE_NUMBER_INDEX);
    }

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

    }

    @Override
    protected Object clone() throws CloneNotSupportedException {

        throw new CloneNotSupportedException();
    }

}

public class Util {

    private static WeakReference<Context> applicationContext;

    public static Context getApplicationContext() {
        return applicationContext.get();
    }

    public static void setApplicationContext(Context context) {
        applicationContext = new WeakReference<Context>(context);
    }
}

public class NameOfApp extends Application {

    public static SQLiteDatabase db;

    @Override
    public void onCreate() {

          super.onCreate();

          try{

               // this will create the database if required (e.g. new install or db deleted)
               db=new Database(this.getBaseContext()).getWritableDatabase();

          } catch (Exception e) {

               // TODO add alert and quit
               Log.e(TAG,"Error creating DB:" + e.getMessage());
               Toast.makeText(getApplicationContext(), "Error creating DB:" + e.getMessage(), Toast.LENGTH_LONG).show();

        }

    } // onCreate

    @Override
    public void onTerminate(){
         Log.d(TAG, "Application.onTerminate() database closed");
         super.onTerminate();
         savePreferences();
         db.close();
    }

    public void closeDB(){
          db.close();
          Log.d(TAG,"Database closed on request");
    }

    protected SQLiteDatabase getwritableDatabase(){
        return db;
    }

}