Android: Button within ListView not receiving onClick events

I am making a date picker activity that looks like a scrolling 30 day month/calendar (think Outlook calendar). The date picker contains a ListView (for scrolling) of MonthView views each of which is a TableView of the individual days. Each individual day in the MonthView is a button. When the MonthView is instantiated I walk each of the days (buttons) and attach a click listener:

final Button b = getButtonAt(i);
b.setOnClickListener(new OnClickListener()
{
      @Override
      public void onClick(View v) {
            setSelectedDate(buttonDayClosure, b);
      }
});

setSelectedDate does a variety of things, but it also turns the button's background to yellow to signify the date is selected.

On my emulator, everything works as you would expect. Activity comes up, you press a day, the day turns yellow. No problems.

However, on some of my peer's emulators and on physical devices when you touch a day nothing happens... until you scroll the ListView... and then all of a sudden the selected day turns yellow. So, for example, you touch "the 3rd" and then nothing happens. Wait a few seconds and then scroll the ListView (touching an area of the calendar that is NOT the 3rd) and as soon as ListView scrolls the 3rd magically turns yellow.

On my peer emulators that show this behavior, I can set a breakpoint on the fist line of onClick and I see that the BP is in fact not hit until the ListView is scrolled.

This behavior doesn't make any sense to me. I would expect the onClick behavior to be unrelated to the encapsulating View's scrolling efforts.

Any thoughts on why this might be the case and how I can rectify the situation so that onClicks always happen immediately when the button is touched?

Thanks.

Post Scriptus: ArrayAdapter and ListView code requested:

public class MonthArrayAdapter extends ArrayAdapter<Date> {

    private MonthView[] _views; 

    private Vector<Procedure<Date>> _dateSelectionChangedListeners = new Vector<Procedure<Date>>();

    public MonthArrayAdapter(Context context, int textViewResourceId, Date minSelectableDay, Date maxSelectableDay) {
        super(context, textViewResourceId);
        int zeroBasedMonth = minSelectableDay.getMonth();
        int year = 1900 + minSelectableDay.getYear();

        if(minSelectableDay.after(maxSelectableDay))
        {
            throw new Il开发者_StackOverflow社区legalArgumentException("Min day cannot be after max day.");
        }

        Date prevDay = minSelectableDay;
        int numMonths = 1;
        for(Date i = minSelectableDay; !sameDay(i, maxSelectableDay); i = i.addDays(1) )
        {
            if(i.getMonth() != prevDay.getMonth())
            {
                numMonths++;
            }
            prevDay = i;
        }

        _views = new MonthView[numMonths];

        for(int i = 0; i<numMonths; i++)
        {
            Date monthDate = new Date(new GregorianCalendar(year, zeroBasedMonth, 1, 0, 0).getTimeInMillis());
            Date startSunday = findStartSunday(monthDate);
            this.add(monthDate);
            _views[i] = new MonthView(this.getContext(), startSunday, minSelectableDay, maxSelectableDay);

            zeroBasedMonth++;
            if(zeroBasedMonth == 12)
            {
                year++;
                zeroBasedMonth = 0;
            }
        }

        for(final MonthView a : _views)
        {
            a.addSelectedDateChangedListener(new Procedure<MonthView>()
            {
                        @Override
                    public void execute(MonthView input) {

                        for(final MonthView b: _views)
                        {
                            if(a != b)
                            {
                                b.clearCurrentSelection();
                            }
                        }

                        for(Procedure<Date> listener : _dateSelectionChangedListeners)
                        {
                            listener.execute(a.getSelectedDate());
                        }
                    }
            });
        }




    }

    void addSelectedDateChangedListener(Procedure<Date> listener)
    {
        _dateSelectionChangedListeners.add(listener);
    }

    private boolean sameDay(Date a, Date b)
    {
        return a.getYear() == b.getYear() && a.getMonth() == b.getMonth() &&
               a.getDate() == b.getDate();
    }

    @Override
    public View getView (int position, View convertView, ViewGroup parent)
    {
        return _views[position];
    }


    private Date findStartSunday(Date d)
    {
        return d.subtractDays(d.getDay());
    }

    public void setSelectedDate(Date date)
    {
        for(MonthView mv : _views)
        {
            mv.setSelectedDate(date);
        }
    }



}

and

public class DatePicker extends ActivityBase {

    public static final String CHOSEN_DATE_RESULT_KEY = "resultKey";

    public static final String MIN_SELECTABLE_DAY = DatePicker.class.getName() + "MIN";

    public static final String MAX_SELECTABLE_DAY = DatePicker.class.getName() + "MAX";

    private static final String SELECTED_DATE = UUID.randomUUID().toString();

    private long _selectedDate = -1;

    private MonthArrayAdapter _monthArrayAdapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Date now = new Date();

        Bundle inputs = this.getIntent().getExtras();

        long min = inputs.getLong(MIN_SELECTABLE_DAY, 0);

        Date minSelectableDate;
        if(min == 0)
        {
            minSelectableDate = new Date(now);
        }
        else
        {
            minSelectableDate = new Date(min);
        }
        Log.i(DatePicker.class.getName(), "min date = " + minSelectableDate.toString());
        long max = inputs.getLong(MAX_SELECTABLE_DAY, 0);

        Date maxSelectableDate;
        if(max == 0)
        {
            maxSelectableDate = new Date(now.addDays(35).getTime());
        }
        else
        {
            maxSelectableDate = new Date(max);
        }


        setContentView(R.layout.date_picker);

        Button doneButton = (Button) findViewById(R.id.DatePickerDoneButton);

        if(doneButton == null)
        {
            Log.e(this.getClass().getName(), "Could not find doneButton from view id.");
            finish();
            return;
        }

        doneButton.setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v) {
                Intent result = new Intent();
                result.putExtra(CHOSEN_DATE_RESULT_KEY, _selectedDate);
                setResult(RESULT_OK, result);
                finish();
            }
        });

        Button cancelButton = (Button) findViewById(R.id.DatePickerCancelButton);

        if(cancelButton == null)
        {
            Log.e(this.getClass().getName(), "Could not find cancelButton from view id.");
            finish();
            return;
        }

        cancelButton.setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v) {
                setResult(RESULT_CANCELED, null);
                finish();
            }
        });

        ListView lv = (ListView)findViewById(R.id.DatePickerMonthListView);
        lv.setDividerHeight(0);


        _monthArrayAdapter = 
            new MonthArrayAdapter(this, android.R.layout.simple_list_item_1, minSelectableDate, maxSelectableDate);

        _monthArrayAdapter.addSelectedDateChangedListener(new Procedure<Date>()
                {

                    @Override
                    public void execute(Date input) {
                        _selectedDate = input.getTime();

                    }


                });

       lv.setAdapter(_monthArrayAdapter);
    }

    @Override 
    public void onRestoreInstanceState(Bundle savedInstanceState)
    {
        if(savedInstanceState.containsKey(SELECTED_DATE))
        {
            _selectedDate = savedInstanceState.getLong(SELECTED_DATE);
            _monthArrayAdapter.setSelectedDate(new Date(_selectedDate));
        }
    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState)
    {
        savedInstanceState.putLong(SELECTED_DATE, _selectedDate);
    }

 }

Having the same problem, looking for an answer. I totally didn't believe it when I didn't get my onClick method until I scrolled my list. I'll post the answer here if I find it.

Right now, my best guess is to try different events besides click (because the scroll space is eating the complex touch events that turn into a click event):

"downView" is a static variable to track the element being clicked.

view.setOnTouchListener(new View.OnTouchListener() {
  @Override
  public boolean onTouch(View v, MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
      downView = v;
      return true;
    } else if (event.getAction() == MotionEvent.ACTION_UP) {
      if (downView == v) {
        handleClick(v);
        return true;
      }
      downView = null;
    }
    return false;
  }
});

The main reason is that ListView doesn't like an adapter having an array of views.

So the problem is triggered by

public View getView (int position, View convertView, ViewGroup parent)
{
    return _views[position];
}

When looking at the ListView code (or rather it's parents AbsListView.obtainView method) you'll see code like

    if (scrapView != null) {
        ...
        child = mAdapter.getView(position, scrapView, this);
        ...
        if (child != scrapView) {
            mRecycler.addScrapView(scrapView);

It can happen that getView(position,...) is called with scrapView != _views[position] and hence scrapView will be recycled. On the other hand, it is quite likely that the same view is also added again to ListView, resulting in views having a weird state (see this issue)

Ultimately, this should be fixed in ListView IMO, but temporarily, I advise against using an adapter containing an array of views.

So I'll add a completely separate answer to this outside of manually composing your own click events from touch events.

I traded some emails with the Android Team (there's a few perks from being consumed by the googly) and they suggested that my attempt to implement ListAdapter by hand was inefficient and that if I don't correctly hook up the data observer methods of the adapter it can cause "funny problems with event handling."

So I did the following:

1) Replaced my implementation of ListAdapter with a subclass of BaseAdapter that overrode the necessary functions.

2) Stopped using list.invalidateViews() and started using adapter.notifyDataChanged()

and the bug seems to have gone away.

That's more work than manually composing a click event, but it's also more correct code in the long run.

Aswer is:

public View getView(int position, View convertView, ViewGroup parent) {
    View v=makeMyView(position);
    v.setFocusableInTouchMode(false);
    return v;
}