CODEWITHSUNDEEP
android
rciovati
rciovati

Reputation: 28063

Performances question when populating ListView with AsyncTask

Actually i use an AsyncTask for populating my ListView. Code looks like that:

private class MyAsyncTask extends AsyncTask<Void, Message, Void> {

    ArrayAdapter<Message> adapter;

    public MyAsyncTask{
        adapter =   ( ( ArrayAdapter<Message> ) mListView.getAdapter();
    }

    @Override
    protected void onPreExecute () {
        adapter.clear();
        super.onPreExecute();
    }

    @Override
    protected void onProgressUpdate ( Message... values ) {
        adapter.add( values[0] );
        super.onProgressUpdate( values );
    }

    @Override
    protected Void doInBackground ( Void... params ) {

        //Getting my messages

        for ( Message message : messages ) {
            publishProgress( message );
        }

        //Other heavy stuff

        return null;
    }
}

With traceview i saw that there is a big overhead due to the publishProgress called in a cycle. I thought that to modify code like that:

private class MyAsyncTask extends AsyncTask<Void, Message, Void> {

    ArrayAdapter<Message> adapter;
    List<Message> messages;

    public MyAsyncTask{
        adapter =   ( ( ArrayAdapter<Message> ) mListView.getAdapter();
    }

    @Override
    protected void onPreExecute () {
        adapter.clear();
        super.onPreExecute();
    }

    @Override
    protected void onProgressUpdate ( Void... values ) {
        for(Message message: messages){
            adapter.add(message);
        }
        super.onProgressUpdate( values );
    }

    @Override
    protected Void doInBackground ( Void... params ) {

        messages =  //Getting my messages

        publishProgress();

        //Other heavy stuff

        return null;
    }
}

This looks line more fast because there are less Messages to send between background thread and ui thread but i'm afraid to run into ANR if my List is very big. Any pattern to optimize this kind of problems?

Thanks :)

Upvotes: 0

Views: 426

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006869

With traceview i saw that there is a big overhead due to the publishProgress called in a cycle.

That is a bit surprising.

Any pattern to optimize this kind of problems?

Add the items to your adapter in doInBackground() and do something else as a progress indicator, such as a ProgressBar.

Upvotes: 1

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