Question

I have a DB that I use in all my activities. There is only one record in the DB.

In the first activity it is opened or created and then put in my globally used object like this

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // first get the current data from the DB
        myDBAdapter = new MyDBAdapter(this);
        GlobalVars.myDBAdapter = myDBAdapter; // we store the DBAdapter in our global var

        myDBAdapter.open();

        Cursor cursor = myDBAdapter.fetchMainEntry();
        startManagingCursor(cursor);
        // if there is no DB yet, lets just create one with default data
        if (cursor.getCount() == 0) {
            createData();
            cursor = myDBAdapter.fetchMainEntry();
            startManagingCursor(cursor);
        }

Now in another activity I access the already open DB like this…

GlobalVars.myDBAdapter.updateMainEntry(1,.....);

I do not close the DB when leavin one activity to go to the next. The DB is just accessed (since it has been opened at the very first activity).

Only when leaving the app I clode the DB like this…

@Override
    protected void onDestroy() {
        super.onPause();
        myDBAdapter.close();

    }

The background why I am also asking this is I get this error…

Finalizing cursor android.database.sqlite.SQLiteCursor@48106730 on
mainEntry that has not been deactivated or closed

and it seems that my app crashes on certain devices – but I can’t find the reason for it during debugging.

Is that correct and best practice, or do I have to close the DB when I leave the activity and open it when entering the next activity when switching between activities?

Many thanks!

Answer 1

The best thing (I have it tested in a few apps of mine) is to:

• declare database adapter as an activity’s instance variable:

  private DBAdapter mDb;

• create it and open in activity’s onCreate():

  mDb = new DBAdapter(this);
  mDb.open();

• close it in activity’s onDestroy():

  mDb.close();
  mDb = null;

Works like charm.
A side note: the Application class onTerminate “will never be called on a production Android device” according to the docs.