Develop Reference

Recyclerview inside fragment inside viewpager notifydatasetchanged not working

I have a recyclerview inside a fragment and that fragment is inside a view pager.
notifydatasetchanged() is not working even though the same code works in other projects of mine. The only difference I can see is that it is inside a view pager now?.
This is how notify the change:
public void updateRecyler(){
// Clear the current array
alarmsFromSP.clear();
// Update the array (This is working the array size is changing)
alarmsFromSP.addAll(AlarmCollection.getAlarms(getActivity()));
// Notify the change
adapter.notifyDataSetChanged();
}
I create the recylerview in oncreate like this:
public class FragmentAllAlarms extends Fragment {
// Arraylist of the alarm data from the strings
ArrayList<Alarm> alarmsFromSP;
tabRefreshReceiver r;
RecyclerView rv;
AlarmsAdapter adapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_all_alarms, container, false);
// Recycler
rv = (RecyclerView) v.findViewById(R.id.mainAlarmRecyclerView);
rv.setLayoutManager(new LinearLayoutManager(getActivity()));
// Get saved data for alarms from the shared preferences string
alarmsFromSP = AlarmCollection.getAlarms(getActivity());
System.out.println("StringIs"+alarmsFromSP.size());
// Adapter
adapter = new AlarmsAdapter(getActivity(), alarmsFromSP);
rv.setAdapter(adapter);
Is it possible I am losing reference to the array or is it somthing to do with the viewpager?
I have been stuck with this for two days now any help is greatly appreciated.
Thanks in advance

make sure that updateRecyler() is called,
and try to change adapter.notifyDataSetChanged(); to rv.getAdapter().notifyDataSetChanged();
this worked for me once.

I have faced the same problem, then I found a temporary solution, instead of using notifyDataSetChanged() use
recyclerView.setAdapter(adapter);
recyclerView.scrollToPosition(postion);

Loading a new ViewHolder based on click event

Within RecyclerView, any tips on loading a different viewholder onitemclick? i'm having trouble wrapping my head around loading viewholder 2 when item is clicked in viewholder 1 at that position. both viewholder 1 and 2 are a list of cards. so say for example. vh1 contains a sample hotel image. When you click that vh2 shows you contact details of that hotel - at that position, while retaining vh1 through out the other un-clicked contents.
I did ask a question like this before and i think it was a bit vague so people suggested i change information based onitem click. The problem is vh1 and 2 are different layouts completely so this wouldn't work for what i'm working on.
is this even possible?
Thanks

You can create another adapter for your RecyclerView. Create a new Java class, call it whatever you want. In your main activity, or the activity where you're setting your adapter, you can create a function like this:
public void setNewAdapter() {
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.your_recyclerview_id);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
NewAdapter adapter = new NewAdapter(// any arguments);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(adapter);
}
In your adapter, you can create a new instance of your activity. For example, if you're activity is called MainActivity, you can add this code in your onItemClick:
MainActivity mainActivity = new MainActivity();
mainActivity.setNewAdapter();
See if that works.

Add fragments dynamically

I need to show text below image but with horizontal swipe functionality. That is every time a person swipes horizontally image and text is updated. But the problem is I don't know the number of images with text beforehand as they are returned by server. How can I proceed with this?

Use a ViewPageAdapter to achieve this functionality. The first step is to obtain the images and the corresponding text from the server. I would prefer to customize the server to return it json array.
With the obtained value from server, write an adapter something similar to below. Here myValues will be the array where all the values in the server will be stored.
Create a Fragment (below MyFragment) with a static method that will return a new instance of the fragment with desired values set.
Now as you swipe, the method getItem(pos) will be called and a new instance of fragment will be shown to the user.
private class MyPagerAdapter extends FragmentPagerAdapter {
ArrayList<Values> myValues = new ArrayList<Values>();
public MyPagerAdapter(FragmentManager fm,ArrayList<Values> val) {
super(fm);
this.myValues = val;
}
#Override
public Fragment getItem(int pos) {
return MyFragment.newInstance("text","image");
}
#Override
public int getCount() {
return myValues.length();
}
}
}
Hope this helps. :)

use a RecyclerView with Horizontal Scroll.
recyclerview = (RecyclerView) view.findViewById(R.id.recyclerview);
layoutManager = new LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false);
recyclerview.setLayoutManager(layoutManager);
recyclerview.setItemAnimator(new DefaultItemAnimator());
recyclerview.setHasFixedSize(true);
recyclerview.setAdapter(adapter);

You need to update textView (either in separate fragment or in the same activity) inside onSwipeLeft or onSwipeRight.
To have these callbacks you need to create your custom listener that extends the TouchListener.
Great example of doing this is here.

How to set different data onto a fragment/viewpager

I've looked around but couldn't find any solutions, so this is my last resort.
I'm working on a Xamarin-Android project and I've got a viewpager with one fragment. The trick with this fragment is that even though it's only one fragment, it loads many instances of this one fragment, depending on how many I need but the problem is that each fragment needs to load one object (one set of data). The problem I have is that when I iterate through the list of returned items (loaded from a file), it obviously loops through everything and sets the last set of returned data onto my fragment. This causes me to have many fragments with the same data. What I need is to load one set of data onto each fragment instead of it loading the last set onto my fragment. So in essence, I have one fragment which loads many instances and each instance needs to show one object's data. How do I do this?
Thanks in advance for any assistance.
Okay, please see below - This is the fragment class. I've left out the OnCreateView of the fragment, as it only inflates the fragment resource and gets the textviews etc. Let me know if you need the FragmentPagerAdapter code as well. This one fragment has many instances, which is set in the FragmentPagerAdapter class in the Count and GetItem overidden methods. Count returns the number of instances required and GetItem which does "return ThisFragment.newInstance(position);"
EDIT: Code updated with solution
private int mNum;
private string code, status;
TextView textviewMyObjectCode, textviewMyObjectStatus;
public static ThisFragment newInstance(int num)
{
ThisFragment myFragment = new ThisFragment();
MyObject myObject = new MyObject();
List<MyObject> myObjectList = MyObjectIO.LoadMyObjectsFromFile();
myObject.MyObjectNumber = myObjectList[num].MyObjectNumber;
myObject.MyObjectStatus = myObjectList[num].MyObjectStatus;
args.PutInt("num", num);
args.PutString("objectCode", myObject.MyObjectNumber);
args.PutString("objectStatus", myObject.MyObjectStatus);
myFragment.Arguments = args;
return thisFragment;
}
public override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
mNum = Arguments != null ? Arguments.GetInt("num") : 1;
code = Arguments.GetString("objectCode");
status = Arguments.GetString("objectStatus");
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
if (container == null)
{
return null;
}
View thisView = inflater.Inflate(Resource.Layout.object_fragment, container, false);
textviewObjectStatus = thisView.FindViewById<TextView>(Resource.Id.textviewObjectStatus);
textviewObjectCode = thisView.FindViewById<TextView>(Resource.Id.textviewObjectCode);
textviewObjectCode.Text = code;
textviewObjectStatus.Text = status;
return thisView;
}

It should be the responsibility of the 'FragmentPagerAdapter' to create new Fragments. You seem to have delegated this responsibility to a Fragment class which is not the right approach. Here you are setting text of 'textviewMyObjectCode' and 'textviewMyObjectStatus' again and again in a loop so these values will get over-ridden in every iteration of the loop.
Ideally you should access 'MyObjectList' in 'newInstance' and set the values in Bundle objects as per the index passed in 'num'. Also 'newInstance' should be part of 'FragmentPagerAdapter' and 'MyObjectList' should be available to 'FragmentPagerAdapter'.
If 'ThisFragment' is the Fragment which is needed to be part of ViewPager then that fragment should just do the job of retrieving its data from the Bundle and set the needed data to its resources.

I managed to figure it out. Since I am using the newInstance method, which contains a position variable called "num" and because I get a list of objects from the LoadObjectsFromFile method, I can assign a specific object to a specific fragment. Example: I can load object[0] onto fragment[0]. I do this in the newInstance method, set the values to a Bundle and then retrieve it later in OnCreate. Then in OnCreateView, I can place the values onto my textviews. #Jay, I now realize what you were saying all along. It didn't click initially :)

Can a ListView contain Fragments

As in, can the ELEMENTS of a ListView be Fragments. I know that you can assign a TextView XML to a ListView to change the way it looks, but can you add Fragments into a ListView.
For instance: I have a Fragment. The XML for said Fragment contains an ImageView, a couple of large-style TextViews, and a small-style TextView. The Fragment class code receives a Bundle, then based on the contents populates the TextViews and ImageView accordingly. Both the Fragment XML and the Fragment code work without issue
(I can display an individual Fragment just fine). I have a FragmentActivity in which I want to display the aforementioned list of Fragments. Here is the code I'm using to try to populate the ListView inside of the FragmentActivity's View:
ArrayList<Fragment> fragList = new ArrayList<Fragment>();
Fragment fragment = Fragment.instantiate(this, TileItem.class.getName());
Bundle bundle = new Bundle();
bundle.putInt("key", 0);
fragment.setArguments(bundle);
fragList.add(fragment);
ArrayAdapter<Fragment> adapter = new ArrayAdapter<Fragment>(this, R.layout.tile_item, fragList);
listItems.setAdapter(adapter);
Here's my mode of thinking on this. I make an ArrayList of Fragments to hold all of my instantiated Views. I then create a Fragment, create a Bundle, add data to the Bundle (so that the Fragment can marshal data into it's Views correctly), add the Bundle to the Fragment, then finally add the Fragment to the ArrayList. After that, I make an ArrayAdapter, add the element layout I want to use, and the list of Fragments I've made; then set the ListView to read from my adapter.
Anyone running this code will likely get the NPE # instantiating the ArrayAdapter. What gives? Is this even possible? Before I keep racking my brain on this can someone tell me if I'm just wasting my time? Is there a better way? I've been thinking of using a ScrollView, but so much of the functionality of a ListView would need to re-implemented and I hate-hate-hate reinventing the wheel when it's not necessary.
Thanks to anyone reading, and especially thank you for your thoughts if you decide to leave them. I've tried searching around for an established answer to this but all I seem to find are questions/web pages concerning using a ListView INSIDE of a Fragment; not using Fragments AS THE ELEMENTS of a ListView
Edit: I took the suggestions below and started investigating more. From the way things appear I should be able to use a custom adapter that inflates fragments instead of just flat out building from XML (for lack of a better way to describe the process) However, my current implementation is throwing an NPE when trying to set the adapter.
Here is my custom adapter code (shortened for brevity):
public class AdapterItem extends ArrayAdapter<Fragment> {
Context c;
List<Fragment> f;
public AdapterItem(Context c, List<Fragment> f) {
super(c, R.layout.tile_item, f);
this.c = c;
this.f = f;
}
#Override
public View getView(int pos, View v, ViewGroup vg) {
LayoutInflater i = (LayoutInflater) c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
return i.inflate(R.layout.tile_item, vg, false);
}
}
and here is how I'm implementing it:
ArrayList<Fragment> fragList = new ArrayList<Fragment>();
Fragment fragment = Fragment.instantiate(this, TileItem.class.getName());
Bundle bundle = new Bundle();
bundle.putInt("key", 0);
fragment.setArguments(bundle);
fragList.add(fragment);
AdapterItem adapter = new AdapterItem(this, fragList);
adapter.add(fragment);
listItems.setAdapter(adapter);
So it's been a few days and I'm pretty sure this thread has been buried. However, I thought I would add one last update just in case someone wants to try this and a google search brings them here. So in my implementation I'm getting an NPE when the ListView is given the adapter. It doesn't take a rocket surgeon to figure out that it's certainly the adapter and not the ListView throwing the error. For the life of me I can't figure out why though...
At any rate, I think I have some idea though. First, a little back story: A while back I was trying to make FragmentTransactions inside of a FragmentDialog. Everytime I attempted to do so, I would get an NPE. Eventually, through much research, I discovered that the reason pertained to the way that Fragments are instanced. When a Fragment is called it needs the context from it's parent. Since a Dialog's parent is the Activity that started it, the Dialog itself didn't meet the criteria necessary. I believe, that when attempting to add fragments to a ListView, this is also the case. Since the ListView doesn't meet the agreement with instancing a Fragment it throws the NPE and thus, leaves me hanging and going back to conventions. D#mn...I had really hoped I would be able to do this. Using Fragments instead of simple XML would have made it so much easier to organize/search through the list. Oh well... guess it can't be done in case anyone is wondering.

I'd say this is not possible to do as putting a fragment in a ListView would mean the fragment can be multiplied across multiple containers. When you use the FragmentManager to create a fragment, it is tagged with an identifier, making it simple to reload and rearrange on orientation and other configuration changes. It also encourages uses across multiple device configs.
A Fragment is really a subset of an Activity. Would you ever have an Activity as part of a list? Definitely not (should be the answer!)!!!
Moreover, it is not very useful to attach() and detach() a fragment continuously as they move in and out of view (cells get recycled). These are all expensive operations that a ListView shouldn't deal with. Lists should scroll quickly.
From the conversation on the comments, I can see you want to achieve nice code with a good separation of view setup code and adapter in the Activity. Do so with either:
Override the View class and do your custom drawing and setup there.
Create a new class, in which you supply a context and data set required for it to get you back the view a list needs to show - this is what I usually do.
Have a Utils class to build your video elsewhere (silly).
Just don't use Fragments in Lists. Not the use case they are aiming for. HTH.

It turns out that you can create a ListView where each item in the listView is a Fragment. The trick is wrapping the Fragment in a FrameLayout.
UPDATE 9/16/2014
Even though it is possible to create a ListView that contain Fragments, it doesn't look like it's a good idea. This seems to definitely be a corner case in the Android world and there be dragons. For a simple fragment like the one in the example below everything works beautifully, but if you have a complex project with a lot going on in it then this is probably not the way to go. My new approach is to pull all of the GUI related code into a View that extends FrameLayout, and insert that into a the ListView -- this works MUCH BETTER and is more in line with how Android expects to be used. If you need the functionality of a Fragment in other parts of your code, you can simply use this new View there too.
Back to the original answer...
I've added a new ManyFragments example to my AnDevCon 14 Fragments example app if you want to try it out. Essentially it comes down the the BaseAdapter, which in my example looks like this:
BaseAdapter adapter = new BaseAdapter() {
#Override public int getCount() { return 10000; }
#Override public Object getItem(int i) { return new Integer(i); }
#Override public long getItemId(int i) { return i; }
#Override
public View getView(int i, View view, ViewGroup viewGroup) {
if (view!=null){
ManyListItemFragment fragment = (ManyListItemFragment) view.getTag();
fragment.setCount(i);
} else {
FrameLayout layout = new FrameLayout(getActivity());
layout.setLayoutParams(frameLayoutParams);
int id = generateViewId();
layout.setId(id);
ManyListItemFragment fragment = new ManyListItemFragment();
fragment.setCount(i);
getChildFragmentManager()
.beginTransaction()
.replace(id,fragment)
.commit();
view = layout;
view.setTag(fragment);
}
return view;
}
};
In case you're curious here's generateViewId():
#TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
public static int generateViewId() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
for (;;) {
final int result = sNextGeneratedId.get();
// aapt-generated IDs have the high byte nonzero; clamp to the range under that.
int newValue = result + 1;
if (newValue > 0x00FFFFFF) newValue = 1; // Roll over to 1, not 0.
if (sNextGeneratedId.compareAndSet(result, newValue)) {
return result;
}
}
} else {
return View.generateViewId();
}
}
private static final AtomicInteger sNextGeneratedId = new AtomicInteger(1);

You don't need to use Fragments.
Write a custom ViewAdapter and have it inflate a more complex layout (or maybe several more complex layouts if you need to get really fancy) then populate the fields of the layout as necessary.
[Aside: to the people who answered in comments -- please use answers rather than comments if you are actually answering the question! If only because you get more reputation points that way!]