We Keep Coding

Reload recyclerview

I am new to android and I am having a problem reloading (rebuilding) as recyclerview after the activity is active. The activity with the recyclerview is a second activity started as an intent on the main activity. I can load it up, and show a list of items. When one of the items is clicked a third activity is launched. The problem is sometimes there are too many items on the list. I want to add a way of selecting an item more easily. I added a spinner on the same activity as the recyclerview. When an item is selected on the spinner, I want to reload a shorter version of the list, based on the spinner selection. However, I can't find a way to achieve that. Any help or suggestions pointing me in the right direction will be greatly appreciated.

as #bink said without code it's hard to help, but the idea in general is that on your spinner.setOnItemSelectedListener() you populate your recyclerView, so everytime you change the selection you get a new list depending on the choosed value.
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
ArrayList<> arrayList = new ArrayList<>();
// add your items based on item spinner.itemSelected
// for(---)
adapter = new MyAdapter(context, arrayList );
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(context));
});
You can also add a filter to your recycler view (https://medium.com/android-news/filterable-recyclerview-in-android-the-how-to-a9ade9cd26)
If you dont want to recreate all the recycler view and the list itselft, use adapter.notifyDataSetChanged();

ArrayAdapter with Json Parsing

i'm doing a system of news feed, so, i've a difficulty for adapter my ArrayAdapter insert value into ListView, with: "username, name, picture, content and others values" i'm newbie in Android Studio.
Searching the internet I found this function
HashMap<String,String> persons = new HashMap<String,String>();
persons.put(TAG_ID,id);
persons.put(TAG_NAME,name);
persons.put(TAG_ADD,address);
personList.add(persons);
}
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, personList, R.layout.list_item,
new String[]{TAG_ID,TAG_NAME,TAG_ADD},
new int[]{R.id.id, R.id.name, R.id.address}
);
list.setAdapter(adapter);
But, i use ArrayList and ArrayAdapter:
ArrayList<Post> postList =
new JsonConverter<Post>().toArrayList(s, Post.class);
ArrayList<String> postador = new ArrayList<String>();
for(Post value: postList){
postador.add(value.id_postador);
postador.add(value.post_legenda);
if(value.post_foto != null) {
postador.add(value.post_foto);
}
postador.add(value.post_data);
postador.add(value.curtidas);
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(
MainActivity.this,
android.R.layout.simple_list_item_1, postador
);
lvPost.setAdapter(adapter);
I tried it, but no success.
ArrayAdapter<String> adapter = new ArrayAdapter<String>(
MainActivity.this,
R.layout.list_item, postador, new String[]{TAG_ID,TAG_NAME,TAG_ADD},
new int[]{R.id.id, R.id.name, R.id.address}
);
There a method convert ListAdapter in ArrayAdapter or adapter my ArrayAdapter for ListAdapter?

If you are a newbie to Android, I would like to recommend few things to you.
1). Start Using RecyclerView from the very beginning instead of ListView. It is more advanced, flexible and efficient version of ListView. You can find a sample demo for the RecyclerView here and here
2). If you still want to use ListView. Then you further have two options, either to use BaseAdapter or ArrayAdapter.
a). Base Adapter as the name suggests, is a base class for all the adapters. If you need more flexibility, you can go with it. You can find the demo sample here and here
b). On the other hand, ArrayAdapter is a concrete BaseAdapter that is backed by an array of arbitrary objects. By default this class expects that the provided resource id references a single TextView.If you want to use a more complex layout, use the constructors that also takes a field id. That field id should reference a TextView in the larger layout resource.To use something other than TextViews (like in your case) for the array display, for instance, ImageViews, or to have some of data besides toString() results fill the views, override getView(int, View, ViewGroup) to return the type of view you want. You can find the demo sample here and here.
Hope it will help you in future and also I suppose you will get answer to your question in the specified demo samples. Thanks and have a good day.. :)

build list from array and allow list to be clickable

I'm trying to build and Android app:
How can I build a list on screen from an array and have the list be clickable?
with a value of the name to be able to use later stored in a String.
What I have now.
String game_list[] = {"game_0","game_2","game_3","game_3","game_4","game_5"};
for(int i=0; i<game_list.length; i++){
myText = myText + game_list[i] +"\n";
}
myTextView.setText("");
myTextView.append(myText);

Also you can use a spinner and adapter
ArrayAdapter<String> adapter = new ArrayAdapter<String>(context, android.R.layout.simple_spinner_item, game_list); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);

Here's a super simple example that I have used: http://www.javacodegeeks.com/2013/06/android-listview-tutorial-and-basic-example.html.
You basically need to make a listview object and add it to whatever view you happen to be using. Then you add "extends ListActivity" to the activity and add your list to the listactivity like so:
ArrayAdapter<String> directoryList = new ArrayAdapter<String>(this,R.layout.file_row, this.directoryEntries);
ListView fileList = (ListView) findViewById(android.R.id.list);
fileList.setAdapter(directoryList);
Call:
protected void onListItemClick(ListView l, View v, int position, long id)
to associate actions with your listview elements

You can build that with ListView control in android and here very good tutorial about it to get more understand how to build it with the array or from any other data source like from database
http://www.vogella.com/tutorials/AndroidListView/article.html
feed be back in any thing not obvious for you

how to call ArrayAdapter constructer from Fragment in Android

I am trying to add a two-column ListView to my android app. When I created the project, I selected the option Fragment which creates that beautiful navigation by sliding to left and right. So my MainActivity extends FragmentActivity.
my problem is when I am trying to add AddayAdapter to ListView, the construstor of ArrayAdapter looks for a context object and I dont know to pass that.
here is the code where I get error
StableArrayAdapter adapter = new StableArrayAdapter(this, R.layout.row , list);
listview.setAdapter(adapter);
When I pass "this", it passes FragmentActivity because the activity extends FragmentActivity. but constructor need a "Context" object.
it gives this error message
"The constructor MainActivity.StableArrayAdapter(MainActivity.DummySectionFragment, int, ArrayList<String>) is undefined"
How can I pass Context object?

You are setting the adapter inside a fragment. Use
StableArrayAdapter adapter = new StableArrayAdapter(this.getActivity(), R.layout.row , list);

StableArrayAdapter adapter = new StableArrayAdapter(getContext(), R.layout.row , list);
listview.setAdapter(adapter);
Did you try passing something like this from your Fragment. Try either getContext() or getApplicationContext().

Unknown fatal exception at Runtime when using Fragments and lists

Afternoon all,
I'm currently learning all about fragments and their use in android apps. I'm trying to populate a listView with an array of Strings. This sort of idea worked when I was populating the list without using fragments but at the moment it's throwing a runtime exception "Unable to start activity". A simple point at where to look would be much appreciated as I can't figure out the logcat reading.
The fragment is thus:
public class setupFragment extends Fragment {
#Override
public void onAttach(Context context) {
super.onAttach(context);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_setup, container, false);
ListView listView = (ListView)getView().findViewById(R.id.listView); //the program seems to at this point
String[] setups = getResources().getStringArray(R.array.setups);
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_1, android.R.id.text1, setups);
listView.setAdapter(arrayAdapter);
return view;
}
}
It's my first time posting java fragments, so any posting errors I apologize for. Cursory breakpoint debugging indicates that the program is breaking on the ListView declaration.
I can post some of the logcat on request, I'm not posting it at the moment due it being long and convoluted.

Replace: ListView listView = (ListView)getView().findViewById(R.id.listView);
with: ListView listView = (ListView) view.findViewById(R.id.listView);
You can't call getView() before returning one from onCreateView().
getView() returns null.

Replace getView() with view, returned object

ListView listView = (ListView)getView().findViewById(R.id.listView);
String[] setups = getResources().getStringArray(R.array.setups);
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_1, android.R.id.text1, setups);
listView.setAdapter(arrayAdapter);
Cut this code and paste it inside onViewCreated method, you cannot get a reference of a view by calling getView() since that view is not attached to that fragment yet.
Also change your getView() to just view.

Your ListView declaration should be as follows :
ListView listView = (ListView) view.findViewById(R.id.listView);
Refer this link to know more about getView() and Fragments. Basically the getView() method returns the root view of the fragment which is nothing but the view returned by onCreateView()