Dianne,
Let me ask this quick question.
Will this sequence of three operations, run consecutively one right after
the other on the UI thread, cause the exception to be thrown
1. Change the count in the base adapter
2. notifyDataSetChanged() // Which will react some time in the future
3. immediately change the count in the base adapter, again
Or another way: when does the ListView grab the BaseAdapter count? Does it
grab it on the call to notifyDataSetChanged() or whenever it later starts
the update operation?
Thank you,
On Thu, Nov 19, 2009 at 2:24 PM, Dianne Hackborn <hack...@android.com>wrote:
> As the exception says:
>
> throw new IllegalStateException("The content of the adapter
> has changed but "
> + "ListView did not receive a notification. Make
> sure the content of "
> + "your adapter is not modified from a background
> thread, but only "
> + "from the UI thread. [in ListView(" + getId() +
> ", " + getClass()
> + ") with Adapter(" + mAdapter.getClass() + ")]");
>
> You can't modify an adapter from a background thread; this must be done on
> the main thread.
>
> This exception is not adding a restriction; it is making it more obvious
> when you do something that would always break in weird, subtle, and/or
> horrible ways.
>
> On Thu, Nov 19, 2009 at 5:56 AM, WoodManEXP <woodman...@gmail.com> wrote:
>
>> For Google about BaseAdapter class
>>
>> In Android 1.6 and 2.0 the BaseAdapter class has apparently been
>> modified to throw an exception when it sees the Adapter.getCount()
>> method return a number different than what it picked up when
>> BaseAdapter.notifyDataSetChanged() was called (at least I did not
>> observe this behavior in pre 1.6).
>>
>> So now the question is, when should one call notifyDataSetChanged() or
>> more importantly, when can the count in the Adapter be safely changed?
>>
>> Consider the case of an app with a background thread delivering data
>> to a BaseAdapter at a rate faster than the ListView responds to
>> notifyDataSetChanged(). Because notifyDataSetChanged() is a
>> synchronous call and the ListView updates are taking place sometime in
>> the indeterminate future on the UI thread, how can an app know when it
>> is safe to change the adapter count?
>>
>> If the app changes the count while the ListView is updating itself the
>> exception will be thrown (and there is no way to catch the exception).
>>
>> Is there a way to know when it is safe to change the count in the
>> BaseAdapter?
>>
>> --
>> You received this message because you are subscribed to the Google
>> Groups "Android Developers" group.
>> To post to this group, send email to android-developers@googlegroups.com
>> To unsubscribe from this group, send email to
>> android-developers+unsubscr...@googlegroups.com<android-developers%2bunsubscr...@googlegroups.com>
>> For more options, visit this group at
>> http://groups.google.com/group/android-developers?hl=en
>>
>
>
>
> --
> Dianne Hackborn
> Android framework engineer
> hack...@android.com
>
> Note: please don't send private questions to me, as I don't have time to
> provide private support, and so won't reply to such e-mails. All such
> questions should be posted on public forums, where I and others can see and
> answer them.
>
> --
> You received this message because you are subscribed to the Google
> Groups "Android Developers" group.
> To post to this group, send email to android-developers@googlegroups.com
> To unsubscribe from this group, send email to
> android-developers+unsubscr...@googlegroups.com<android-developers%2bunsubscr...@googlegroups.com>
> For more options, visit this group at
> http://groups.google.com/group/android-developers?hl=en
--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
