Updating UI elements in ListView row is not not working

Question

I am attempting to update UI elements in a ListView row from my custom adapter. I have no problems when updating from within getView(). But the UI does not update from within my onCheckedChangedListener nor from a method called in onPostExecute() of my AsyncTask. I am using the View Holder pattern, here is my code.

public class InstanceAdapter extends ArrayAdapter<MyInstance> {

    Context context;
    int layoutResourceId;
    List<MyInstance> data = null;
    static InstanceHolder holder = null;
    static Timer myTimer;

    public InstanceAdapter(Context context, int layoutResourceId,
            List<MyInstance> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;

        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            holder = new InstanceHolder();
            holder.spinner = (ProgressBar) row.findViewById(R.id.progressBar);
            holder.state = (TextView) row.findViewById(R.id.instanceState);


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

        final MyInstance instance = data.get(position);
        holder.instanceName.setText(instance.getName());
        holder.state.setText(instance.getState());
        holder.toggle.setChecked(instance.stateSwitch);
        holder.toggle.setEnabled(instance.getEnabled());

        holder.toggle.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton buttonView,
                    boolean isChecked) {

                if (isChecked) {

                    // this does not work
                    holder.spinner.setVisibility(View.VISIBLE);

                    new StartInstancesTask(instance).execute();

                } else {

                    // this does not work
                    holder.spinner.setVisibility(View.VISIBLE);

                }

            }

        });

        return row;
    }

    @Override
    public MyInstance getItem(int position) {
        return data.get(position);
    }

    static class InstanceHolder {
        TextView state;
        ProgressBar spinner;
    }

    protected static class StartInstancesTask extends
            AsyncTask<Void, Void, String> {

        private MyInstance instance;
        private String result;

        public StartInstancesTask(MyInstance instance) {
            this.instance = instance;
        }

        @Override
        protected String doInBackground(Void... params) {
            result = EC2.startInstance(instance.getId());

            return result;
        }

        protected void onPostExecute(final String result) {

            updateState(result);

        }
    }

    public static void updateState(String result) {

        // these ui updates do not work ...

        if (result.equals("pending")) {
            holder.spinner.setVisibility(View.VISIBLE);
        } else if (result.equals("running")) {
            holder.spinner.setVisibility(View.GONE);
        } else if (result.equals("shutting-down")) {
            holder.spinner.setVisibility(View.VISIBLE);
        } else if (result.equals("terminated")) {
            holder.spinner.setVisibility(View.GONE);
        } else if (result.equals("stopping")) {
            holder.spinner.setVisibility(View.VISIBLE);
        } else if (result.equals("stopped")) {
            holder.spinner.setVisibility(View.GONE);
        }

        holder.state.setText(result);

    }
}

I had put in logging statements, and updateResult() is definitely being called correctly. Any ideas?

you are changing the view, which is recycled, when you should be changing the data. — njzk2, Dec 06 '13 at 14:03
and your holder reference changes at every getView call. it can only point to one thing at a time, and that thing is the last view holder that was rendered. — njzk2, Dec 06 '13 at 14:04

score 0 · Accepted Answer · answered Dec 06 '13 at 14:15

0

Use holder.toggle.setTag for getting holder instance for clicked row to update views. try as:

InstanceHolder clicked_holder = null; // to get selected row views

in getView save current row holder using holder.toggle.setTag :

holder.toggle.setEnabled(instance.getEnabled());
holder.toggle.setTag(holder);
holder.toggle.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton buttonView,
                    boolean isChecked) {
                    clicked_holder=(InstanceHolder)buttonView.getTag();
                    //...your code here..     
            }

        });

now use clicked_holder instead of holder which hold last row to updated views in selected row

answered Dec 06 '13 at 14:15

ρяσѕρєя K

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So clicked_holder should be global and holder should be local to getView()? – littleK Dec 06 '13 at 14:33
declare `clicked_holder` as global – ρяσѕρєя K Dec 06 '13 at 14:37
OK, I have it mostly working now. But I still have some crashes. I think that this is because I am referencing clicked_holder directly in my updateState() method without a getTag() assignment. How can I reference the spinner in updateStatus()? – littleK Dec 06 '13 at 14:45
@littleK : put null check before accessing views from `clicked_holder` and also add one more `paramter` in `StartInstancesTask` constructor and `updateStatus` to get clicked_holder – ρяσѕρєя K Dec 06 '13 at 14:47
Did that, same error. Looks like I am not on the main UI thread according to the error: "CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views." It works if I wrap the contents of updateResult() in a Runnable (see answer from http://stackoverflow.com/questions/3280141/android-calledfromwrongthreadexception-only-the-original-thread-that-created). Is that acceptable? I thought that anything called from onPostExecute() is safe? – littleK Dec 06 '13 at 15:04
@littleK make sure you are updating or accessing any UI element inside startInstance method? – ρяσѕρєя K Dec 06 '13 at 15:09

score 0 · Answer 2 · answered Dec 06 '13 at 14:27

Take a look at this post: http://android.kuffs.co.uk/2013/12/custom-list-adapter-with-icon-and.html

Updating the UI in this case is as simple as editing the properties of the CheckedListItem (or similar) class and calling NotifyDatasetChanged on the adapter.

Updating UI elements in ListView row is not not working

2 Answers2