Dynamically adding Views in a RecyclerView only to current item

Question

I'm dynamically adding Views to my items in a RecyclerView. These added Views should only be related to the item which they're added to, but I'm having a problem when I scroll. It seems the View is recycled and a new item is loaded, but those previously added views are still there, only now on the wrong item.

I'm assuming that it's just because the ViewHolder is being reused, so the added items show up again with a new item, when loaded.

How would one go about solving this?

Just to clear are you adding items dynamically to recyclerView or adding new views and populating it with data dynamically? — Anurag Singh, Feb 22 '17 at 07:23
@AnuragSingh yes, but I wound up adding code to onViewRecycled and using "removeAllViews" on the viewholder there. and it worked fine. — CQM, Feb 23 '17 at 16:15
To anyone concerned, my answer to a similar question should be helpful http://stackoverflow.com/questions/32332381/add-a-view-dynamically-to-the-item-of-the-recyclerview/32333608#32333608 — maciekjanusz, Feb 27 '17 at 10:37
Please share your code. There are couple ways to achieve this, e.g. thru adapter or RecyclerView.ItemDecoration. — Vilen, Feb 28 '17 at 15:30

score 5 · Accepted Answer · edited May 23 '17 at 11:47

This was an old question of mine. A bounty was placed on it, hence the surge of popularity and the multiple new and irrelevant answers.

As stated in both my comment to this answer and @CQM's comment below my original question, the answer is to override the onViewRecycled() method and perform any needed operations there. This method is called when a view is recycled, and any cleanup operations can be done here.

Documentation on this method can be found here.

In my case, it was a matter of deleting the invisible TextView's attached to the view. The text itself had been deleted, but the view remained. If many invisible TextView's accumulate on the view and aren't properly recycled when scrolling, the scroll will begin to lag.

score 4 · Answer 2 · answered Jan 01 '16 at 00:21

4

You need to track what views have been added based on the backing data. I would probably add any necessary extra views in onBindViewHolder(), and remove any that might be present in onViewRecycled(). Then when you want to make one appear dynamically, change whatever variable you have tracking whether it should be visible, and call notifyItemChanged().

answered Jan 01 '16 at 00:21

RussHWolf

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So I implemented `onViewRecycled` and am currently looping through all the child layouts in the layout that im adding the new views too, and then checking via `instanceof` if they're the type of view I need to remove, and removing them if so. Is there a simpler way to remove all types of a view from a viewgroup? Also, not really sure what you meant by your last sentence. Im currently adding new views in `onBindViewHolder` as the data for each new view is contained in my data list. I cant just toggle the visibility of the views either because im adding them dynamically. – Orbit Jan 01 '16 at 01:34

score 4 · Answer 3 · edited Jun 20 '20 at 09:12

Based on this:

but those previously added Views are still there, but now on the wrong item.

Basically, as per the RecyclerView documentation, You have to reset the views everytime inside the onBindViewHolder() method,

so let say, you have a method that sets a view param if its your profile, so the code for the same goes as follows,

if (list.get(position).getId()==PreferenceManager.getUserID())
{
  // do some view change here
setViewParam(true);
}else
{
  // reset the view change here
setViewParam(false);
}

So what you're doing here is giving recycled ViewHolder a chance to reset. Do comment if you need help!

score 4 · Answer 4 · answered Feb 28 '17 at 05:43

You can use this! setItemViewCacheSize(int size) Check here RecyclerViewDocumentation.

The offscreen view cache stays aware of changes in the attached adapter, allowing a LayoutManager to reuse those views unmodified without needing to return to the adapter to rebind them.

score 2 · Answer 5 · answered Feb 28 '17 at 15:34

First of all, can you share some more code please?

Second, why would you want to dynamically add new views on fly? Why don't you use different VIEWTYPE or just have those view already on your layout and just make them visible/invisible or visible/gone? (I believe it will be more efficient this way).

Let me remind you something about RecyclerView, yes when user is scrolling viewHolder are being reused (few of them can be created, even more than it needs to fill the screen). So if it happened that you added some views on "item A" and user scroll to "item Z", that viewHolder can be reused for that "item Z", hence the show up of the previously added views.

How can you solve that?

Well always check on every items if you need to add new views, if yes add them if not already added, else always remove those views (if present) to return to default viewHolder state (or whatever you call it).

Hope this will help you.

Because the number of views to be added is variable. For example, users can add 0 customized tags or as many as they want to each record. — g g, Aug 31 '21 at 06:35

score 1 · Answer 6 · answered Feb 27 '17 at 06:37

Save Information by tags for items with new child each time the Add newView operation occur. (In shared preference for example) Tag: create with item position onBindViewHolder.

...
SharedPreference  sharedPref = getSharedPreference("text" + position, context);
SharedPreference.Editor editor = sharedPref.edit();
editor.putString("view", "ImageView");
...

when load Adapter get this value and put default as null. I am not sure about its efficiency but i will work.

...
String viewType = sharedPref.getString("view", null);
//it will return ImageView

if you know some possible viewTypes for example always going to be ImageView & TextView so with some if statement it will be ok.

if(viewType.equals("ImageVIew")){
item(position).addView(new ImageVIew(context));
}

Good Luck

Do not do this. You will be accessing and storing to shared preferences very rapidly when scrolling. — Orbit, Feb 28 '17 at 20:29

score 0 · Answer 7 · edited Feb 27 '17 at 13:02

0

In your adapter class of your recyclerView, in the onBindViewHolder method, create another adapter and do the same methods for your new adapter.

The hierarchy will be,

mainRecyclerView -> item1(->childRecyclerView1) , item2(->childRecyclerView2), item3(->childRecyclerView3)

This way you can achieve what you want without wrong values to be viewed on wrong items.

edited Feb 27 '17 at 13:02

Sampada

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answered Feb 27 '17 at 10:02

saDashiv sinha

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score 0 · Answer 8 · answered Feb 28 '17 at 13:18

You should take any Empty Layout like Linearlayout in your child item layout XML and then add views into that LinearLayout of your particular item in this way when you scroll List all of you child views which you have added to LinearLayout also scroll with that item .

Dynamically adding Views in a RecyclerView only to current item

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