I am creating Android application for an IOT product .
I am uploading sensor data to an web serves developed in REST architecture.
web service is working perfectly .
I want show in real time that if sensor data changes.
I want retrive data and update the Textview
how can I do that?
For refreshing listview data,you need to use the following line of code,
adapter.notifyDataSetChanged();
where,
adapter = your listview adapter object
Write above line of code after you retrieve data from a server or local database.
You want to update a textview or a listview?
If it is that you want to keep adding new records to a list view, just add the items to the listview adapter as they come in and call youradapter.notifyDataSetChanged() so the listview updates its content.
Add this Code in your adapter list like :
Adapter_Constructer(List<String> data){
this.data=data;
notifyDataSetChanged();}
and then update it when u want
or just use :
adapter.notifyDataSetChanged();
in your response method.
or Reinitialize and reset adapter then call adapter.notifyDataSetChanged();
Related
I am using a Exposed dropdownlist in the application which should work like Spinner but when the
new data is attached to the adapter (data downloaded from server)it does not show the updated data instead previous data is shown.
Have you called notifyDataSetChanged or notifyItemRangeInserted after changing adapter data?
I use this
link
to make a pagedList from Room. But i must fetch other data from another remote before set adapter
How can i edit LiveData> results before set data?
I am very new to Android development. I am little confuse about the use of Adapter.notifyDataSetChanged() with ArrayAdapter and ListView. In my project, I am displaying all student in ListView with the help of an ArrayAdapter. The ArrayAdapter is getting the data (ArrayList) from local(Sqlite) database. further, the local database is getting the data from server whenever the server data is changed.
I created the adapter instance in onCreate() and I bound the Listview with it. Whenever the local database is changed, I am trying to refresh the ListView with notifyDataSetChanged() method but somehow its not working.
I have a CustomListView in my android app. Each item consists of two pieces of text which are to be retrieved from an online SQL database. I'm using a Model class called ListModel and a custom adapter called CustomAdapter. I'm using an Asynctask to download the model data from the internet. But the problem is that, adding of a ListModel object to my ArrayList is not working when I do it in the onPostExecute method of my Asynctask. So, the listview is not getting updated. How do I display the Model items on my Custom List as soon as they get downloaded? Is there any way to do that?
This type of problems occures when adapter not properly notify after data downloaded. Notify your adapter in postExecute by notifyDataSetChanged () method
Generally this is because notifyDataSetChanged() isn't called on the arrayadapter. (but stacktraces/your code would be helpful)
In addition, this is a prime use of an in-memory SQLite database (if you plan on doing any custom queries)
Or a full on-disk SQLite DB if you want to cache data.
(Adding a content provider(by just surrounding the SqliteDB) would also be nice if you want to abstract away some more and provide observers, etc. )
After working on an app for a while I realize I use
adapter.clear()
and
arraylist.clear()
I can see both are working just fine, I would like to know the difference between the two!
Both are called before I start and asyncTask that updates my list with information from my server!
You should not be clearing the ArrayList directly. The ArrayAdapter makes absolutely no guarantees that it maintains the same referenced list given to it. In fact it will change when you perform a search with it's filter. Which would make arrayList.clear() fail.
Rule of thumb, if you ever need to mutate or retrieve the associating data...do it directly from the adapter. Not the list you used to construct it.
Adapter = it contains copies of diff views,arrays
aaraylist holds the data which we want to display in our view.
ex: arraylist<HashMap<String,String>> ah= new ArrayList<HashMap<String,String>>();
the above list contains hashmap
if i clear the arraylist there will be no data to show on listview or gridview so it will be empty
if i clear adapter than it will destroy the copies of array and views so the output will be same