Unreleased Resource: Android SQLite Database

An Android activity fails to release the Android database handler in its onPause(), onStop(), or onDestroy() event handlers.

The Android activity maintains an Android SQLite database handler that is not closed in onPause(), onStop(), or onDestroy() callback. The Android OS invokes these callbacks whenever it needs to send the current activity to the background, or when it needs to temporarily destroy the activity when system resources are low. By failing to close the database properly, the activity can potentially exhaust the device of available cursors if the activity is constantly restarted. In addition, depending on the implementation, the Android operating system can also throws DatabaseObjectNotClosedException, which crashes the application if the exception is not caught.

Example 1: The following code describes an Android activity that caches user data and writes the data to disk when the activity is stopped. Note that does not override the base onPause(), which should be used to release the database object, nor does it properly release it during its shutdown sequence.

public class MyDBHelper extends SQLiteOpenHelper {
  ...
}

public class UnreleasedDBActivity extends Activity {
  private myDBHelper dbHelper;
  private SQLiteDatabase db;

  @Override
  public void onCreate(Bundle state) {
      ...
      db = dbHelper.getWritableDatabase();
      ...
  }

  @Override
  public void onRestart() {
      ...
  }

  @Override
  public void onStop() {
      db.insert(cached_data);     // flush cached data
  }
}