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What does "invalid statement in fillWindow()" in Android cursor mean?

Posted by: admin April 23, 2020 Leave a comment

Questions:

I sometimes see this error in my logcat output,

Cursor: invalid statement in fillWindow().

It sometimes happens when I press the back key and then it goes to the default Android listview before going to my custom listview.

What does it mean? How do I solve it? Because it does not point to any line of code where the problem is coming from.

How to&Answers:

When dealing with ListActivities, this issue has to do with the Cursor objects, CursorAdapter objects, and Database objects not being closed properly when the Activity stops, and not being set properly when the Activity starts or resumes.

I had to make sure that I closed my SimpleListAdapter, my Cursors, and then my Database objects in that respective order, in the onStop method of the Activity that is called when the TabActivity resumes.

I had already been closing the Cursor and Database objects, but had not been closing my SimpleListAdapter Cursor.

/**
   * onStop method
   * 
   * Perform actions when the Activity is hidden from view
   * 
   * @return void
   * 
   */
  @Override
  protected void onStop() {
    try {
      super.onStop();

      if (this.mySimpleListAdapterObj !=null){
        this.mySimpleListAdapterObj.getCursor().close();
        this.mySimpleListAdapterObj= null;
      }

      if (this.mActivityListCursorObj != null) {
        this.mActivityListCursorObj.close();
      }

      if (this.myDatabaseClassObj != null) {
        this.myDatabaseClassObj.close();
      }
    } catch (Exception error) {
      /** Error Handler Code **/
    }// end try/catch (Exception error)
  }// end onStop

Answer:

It is of utmost importance that you close the Cursors, Databases, DBHelpers in the right order.

for e.g.
for the given code below.

DBHelper dbhelper = new DBHelper();
SQLiteDataBase db = dbhelper.getWritableDatabase();

Cursor c = db.query(/*some parameters*/);

the order of closing should be like:

c.close();
db.close();
dbhelper.close();

Otherwise different errors keep on spawning and the developer does not even come to know about it. “Cursor: invalid statement in fillWindow()” being one of such errors.

Answer:

Maybe this can help you: http://www.ragtag.info/2011/feb/1/database-pitfalls/

It seems that calls to getReadableDatabase and getWritableDatabase returns the same connection to the database (even if you made several calls to them).
So, any call to close() on any of them will close both connection(s).

If you tries to use a cursor later, you’ll get the nice ‘Invalid statement’, since the connection which the cursor relies on, is already closed.

Answer:

If you are using a custom Class instance e.g. Model m that holds a DatabaseManager, which in turn holds a SQLiteDatabase: Model->DatabaseManager->SQLiteDatabase

Then, if you do a query to m (which does the appropiate delegations) and then you do something like m.close() (which actually closes the SQLiteDatabase) and after that you try to use the Cursor you will get that error.

The solution is: first use the cursor and then close the Db.

My response is based in the 2 existing so far, that inspired me to solve the problem.

Answer:

I am still having issues with the ‘Invalid statement in fillWindow()’ error.

I have narrowed the issue down to the SimpleCursorAdapter cursor for my ListView.

For example, if I am in the listview for an Activity A, and I close the cursor before starting a new Activity B, I don’t get the ‘Invalid statement in fillWindow()’ when I return to Activity A.

However, before Activity B loads, I see the list from Activity A’s listview disappear on the screen, and the ‘No Records Found’ message is displayed briefly before the screen is hidden, before Activity B’s screen is shown.

How can I gracefully resolve this issue?

EDIT:
I actually figured this out this morning. I added

this.stopManagingCursor(this.myListCursor);

to the onPause method in my ListActivity classes, and that resolved the ‘Invalid statement in fillWindow()’ error.