Android how to refresh ListView contents

Question

My ListView is using an extension of BaseAdapter  I can not get it to refresh properly   When I refresh  it appears that the old data draws on top of the new data  until a scroll event happens   The old rows draw on top of the new rows  but the old rows disappear when I start scrolling      I have tried calling invalidateViews    notifyDataSetChanged    and notifyDataSetInvalidated     My code looks something like   private void updateData        List lt DataItems gt  newList   getNewList        MyAdapter adapter   new MyAdapter getContext          my adapter holds an internal list of DataItems    adapter setList newList      mList setAdapter adapter      adapter notifyDataSetChanged       mList invalidateViews

User · Answer

I too have tried invalidate    invalidateViews    notifyDataSetChanged    They all might work in some particular contexts but it did not do the job in my case   In my case  I had to add some new rows to the list and it just does not work  Creating a new adapter solved the issue   While debugging  I realized that the data was there but just not rendered  If invalidate   or invalidateViews   does not render  which it is supposed to   I don t know what would   Creating a new Adapter object to refresh modified data does not seem to be a bad idea  It definitely works  The only downside could be the time consumed in allocating new memory for your adapter but that should be OK assuming the Android system is smart enough and takes care of that to keep it efficient   If you take this out of the equation  the flow is almost same as to calling notifyDataSetChanged  In the sense  the same set of adapter functions are called in either case   So we are not losing much but gaining a lot

User · Answer

To those still having problems  I solved it this way   List lt Item gt  newItems   databaseHandler getItems    ListArrayAdapter clear    ListArrayAdapter addAll newItems   ListArrayAdapter notifyDataSetChanged    databaseHandler close      I first cleared the data from the adapter  then added the new collection of items  and only then set notifyDataSetChanged    This was not clear for me at first  so I wanted to point this out  Take note that without calling notifyDataSetChanged   the view won t be updated

User · Answer

Only this works for me everytime  note that I don t know if it causes any other complications or performance issues   private void updateListView            listview setAdapter adapter

User · Answer

I think refilling the same adapter with different data would be more or most better technique  Put this method in your Adapter class with right argument  the data list you want to display as names in my case  Call this where u update the data of list with updated list  names in my case   public void refill ArrayList lt BeanDatabase gt  names        list clear        list addAll names       list notifyDataSetChanged        If you change the adapter or set the adapter again and again on when the list updates  then force close error would surely cause problems at some point   Error List data been updated but adapter doesn t notify the List View

User · Answer

I m doing the same thing using invalidateViews   and that works for me  If you want it to invalidate immediately you could try calling postInvalidate after calling invalidateViews

User · Answer

Update ListView s contents by below code   private ListView listViewBuddy  private BuddyAdapter mBuddyAdapter  private ArrayList lt BuddyModel gt  buddyList   new ArrayList lt BuddyModel gt       onCreate     listViewBuddy    ListView findViewById R id listViewBuddy   mBuddyAdapter   new BuddyAdapter    listViewBuddy setAdapter mBuddyAdapter     onDataGet  After webservice call or from local database or otherelse    mBuddyAdapter setData buddyList   mBuddyAdapter notifyDataSetChanged      BaseAdapter   private class BuddyAdapter extends BaseAdapter         private ArrayList lt BuddyModel gt  mArrayList   new ArrayList lt BuddyModel gt         private LayoutInflater mLayoutInflater   LayoutInflater  mContext getSystemService Context LAYOUT INFLATER SERVICE       private ViewHolder holder       public void setData ArrayList lt BuddyModel gt  list           mArrayList   list              Override     public int getCount             return mArrayList size                Override     public BuddyModel getItem int position            return mArrayList get position               Override     public long getItemId int pos            return pos             private class ViewHolder           private TextView txtBuddyName  txtBuddyBadge              SuppressLint  InflateParams        Override     public View getView final int position  View convertView  ViewGroup parent            if  convertView    null                holder   new ViewHolder                convertView   mLayoutInflater inflate R layout row buddy  null                  bind views             holder txtBuddyName    TextView  convertView findViewById R id txtBuddyName               holder txtBuddyBadge    TextView  convertView findViewById R id txtBuddyBadge                   set tag             convertView setTag holder             else                  get tag             holder    ViewHolder  convertView getTag                       holder txtBuddyName setText mArrayList get position  getFriendId              int badge   mArrayList get position  getCount            if badge  0               holder txtBuddyBadge setVisibility View VISIBLE               holder txtBuddyBadge setText    badge            else              holder txtBuddyBadge setVisibility View GONE                         return convertView            Whenever you want to Update Listview just call below two lines code    mBuddyAdapter setData Your Updated ArrayList    mBuddyAdapter notifyDataSetChanged      Done

User · Answer

You don t have to create a new adapter to update your ListView s contents  Simply store your Adapter in a field and update your list with the following code   mAdapter setList yourNewList   mAdapter notifyDataSetChanged        To clarify that  your Activity should look like that   private YourAdapter mAdapter   protected void onCreate                      mAdapter   new YourAdapter this       setListAdapter mAdapter        updateData       private void updateData         List lt Data gt  newData   getYourNewData        mAdapter setList yourNewList       mAdapter notifyDataSetChanged

User · Answer

In my understanding  if you want to refresh ListView immediately when data has changed  you should call notifyDataSetChanged   in RunOnUiThread     private void updateData         List lt Data gt  newData   getYourNewData        mAdapter setList yourNewList        runOnUiThread new Runnable              Override         public void run                     mAdapter notifyDataSetChanged

User · Answer

Another easy way     In your ListViewActivity  public void refreshListView         listAdapter   new ListAdapter this       setListAdapter listAdapter

[android] Android: how to refresh ListView contents?

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