CODEWITHSUNDEEP
androidmultithreadingadapterrunnablenotifydatasetchanged
Dmitrij
Dmitrij

Reputation: 13

notifyDataSetChanged() gets updated last

I have a Runnable class that calculates model values for my composite list views, in that runnable there's a UI thread inside of a custom thread. There I have adapter's notifyDataSetChanged() call, but after notifyDataSetChanged() I try updating some TextView value in the main layout. The problem is when running TextView gets updated first and only then ListViews and getting updated. That means notifyDataSetChanged() of the Adapter custom class gets updated last which is not suitable for me. Is there any possibility to synchronize those screen updates?

Here's the sample code:

public class TestRunnable implements Runnable {
    private TestAdapter adapter;

    @Override
    public void run() {
        Context.runOnUiThread(new Runnable() {
            @Override
            public void run() {

                adapter.notifyDataSetChanged();

                MainActivity.setTextViewValue("Something...");
            }
        });
    }
}

public class TestAdapter extends ArrayAdapter<TestModel> {
    @Override
    public View getView(final int position, View view, ViewGroup parent) {
        View row = view;
        TestHolder holder;
        Boolean rowIsNew = false;
        if (row == null) {
            rowIsNew = true;
            LayoutInflater layoutInflater = ((Activity) context)
                    .getLayoutInflater();
            row = layoutInflater.inflate(layoutResourceId, parent, false);

            holder = new TestHolder();
            ...
            row.setTag(holder);
        } else {
            holder = (TestHolder) row.getTag();
        }

        TestModel testModel = data.get(position);
        holder.property = testModel.property;
        ...

        if (rowIsNew) {
            holder.....setTypeface(...);
            holder.....setTypeface(...);

        }

        return row;
    }
}

Upvotes: 0

Views: 83

Answers (2)

Merlevede
Merlevede

Reputation: 8180

I presume your MainActivity.setTextViewValue("Something..."); line is trying to print some data from the adapter and you're getting the old value, is that so?

I'm not 100% sure of this, perhaps someone else can help confirm this, but I think notifyDataSetChanged() only marks the current data on the adapter as dirty, so the adapter will know that it has to refresh the data, but it doesn't do it immediately when you do the call.

EDIT: If my first paragraph is correct, you should try to update the text view with data from the data source instead of the adapter, this would be a nicer way to solve the problem.

Upvotes: 0

Shereef Marzouk
Shereef Marzouk

Reputation: 3392

I have revised the source code of ArrayAdapter and I see no way of executing code after it has called the onChanged() on it's observer so my answer would be:

  1. Implement your own even on onChanged() being called
  2. Call ListView.setAdapter with a brand new adapter with the new dataset

P.S. Number 1 is the optimum solution but number 2 is the easy solution, depending on your time and performance requirement use what you need, but I recommend taking some time and implementing Number 1.

Upvotes: 1

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