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how to update the data in specific position in the recyclerview without notifying the whole item? (Ex. text, image etc)

I need the functionality to update the data in the item in the recycler view. right now, If we notify the whole item it shows some fluctuation and we want to avoid refreshing the whole item on the UI.
I am using the ListAdapter with diff utils.

There are many ways to achieve your goal.
self-managing items. Adapter doesn't know anything about content of the items, it only puts items into RecyclerView. Content is managed by the item itself, so your problem is already solved.
custom adapter. Adapter has intricate knowledge about every item and can update selected ones accordingly.
AsyncListDiffer You can add differ to your adapter and it will take care of not updating parts that need no update.
Without seeing your code, we can't tell which way would be the most appropriate for you, but I guess adding differ is the simplest on already working code.

You need to create custom Adapter:
https://developer.android.com/develop/ui/views/layout/recyclerview

If you're talking about updating specific list items, and you're not using a DiffUtil (which will handle it for you) then you need to call the appropriate notify* method on your Adapter.
They fall into two categories, item change events (where the item list stays the same, but the displayed data for one or more of those items changes) and structural change events (where the actual list of items changes in some way, e.g. insertion/removal, or reordering).
I'm assuming you just want to update the displayed data for an item, so you should use one of the notifyItemChanged or notifyItemRangeChanged methods to inform the adapter that a certain item (or range of items) needs to update. If any of those items are currently being displayed in a ViewHolder, then onBindViewHolder will get called again for those items - which is where you set all your text, images etc depending on the item you're displaying. So you'll update them with the current data.
Both those methods have a version that takes a payload Object/Any, where you can pass in some data to be used in a partial bind - basically, onBindViewHolder can receive that data and be smarter about the update, which means you can avoid things like reloading images, etc. by passing in some stuff and checking for it during the binding process. More info about that here in the other version of onBindViewHolder you can implement, if you need to.

How can I efficiently transfer checked items from a listview to another activity when data is supplied by a Content Provider

The title doesn't really cover it all. It's basically the following use case:
Select a bunch of items in a listview
Move to the next activity
Show the selected items in this new activity in a listview
If the user decides to move to the previous section the same items should still be checked
If I were using POJOs I could simply add an OnItemClickListener to the ListView and add the items to an array each time user clicks an item and ship this array to the new Activity. However the ListView is populated using a Loader which gets the data from a ContentProvider and puts it in a SimpleCursorAdapter.
In the current state I can think of a few possible solutions:
1) Add an extra column to the relevant table of the objects in the ListView. Each time the user selects an item this column is updated to indicate it is selected.
This has a few advantages:
Once I have moved to the next Activity I can simply query for all selected items.
When moving to the previous activity I can use this column to show a selected view.
But also a few disadvantages:
Requires an update each time an item is clicked, triggering the loader.
Requires a custom adapter which uses the state of the new column to decide whether it should or should not be shown as checked. Possibly creating a delay between clicking an item and actually showing it as checked.
The default check options in the ListView will be unusable
2) Track the IDs of checked items (using OnItemClickedListener or getCheckedItemIds) and pass them to the next Activity. In the new activity I then create a selection argument of "ID = ? OR " repeating N times (and excluding the last OR) and use the given array as the selection arguments.
Advantages:
No need to keep updating the database.
No extra columns in the database.
Item checking has no extra delay.
Default check options from the listview still usable
Disadvantages:
Moving to the previous activity is now harder. I could return the list of selected item IDs, but the listview only has the option setItemChecked which takes a position. So I'd have to iterate over the entire adapter to find the positions of the items and set them as checked.
I'm probably capable of implementing them without any hassle. At the moment I'm gravitating towards the second option.
So ultimately I have the following questions:
Is there an easier way to do this in Android.
What would be a good way to recheck the items (see the disadvantage in the second suggestion and if there's no better way to do it).
This ListView will also get a search function which will probably again make it a bit harder because if I'm not mistaken filtering resets it every time. So I'd also have to recheck items every time (ideally during filtering).

Your disadvantage "Requires an update each time an item is clicked, triggering the loader." is not quite true it will trigger only if your ContentProvider calls notifyChange you could have it not to call notifyChange in some specific cases
and pressing back by going to the previous activity shouldn't be that hard only if you explicitly call finish() on your activity, otherwise it should be able to save its state onSaveInstanceState
Either way i would use a third approach and simply wouldn't use a second activity but would keep everything inside a single activity use pearhaps two Fragments one for the initial check list and the second one for your second preselected list and would use callbacks and let the activity manage all,is that possible for your use case ?

Showing animation of Views created from a custom adapter

I'm trying to show an animation with all Views that I've created from an adapter. When I scroll down, it shows the animation correctly, but when I scroll up, I see these Views recreate themselves and show the animation again. Then, when I scroll down, it happens again.
My assumption is that the mechanism of creating a View from an adapter is to load the View into memory; just the group of Views which are on screen right now (but above and below views are not loaded into memory). These will be loaded again when I scroll to these views, right?
Is there any way to fix this problem?
PS: Sorry for my English, I hope you understand my problem.

My assumption is that the mechanism of creating a View from an adapter
is to load the View into memory; just the group of Views which are on
screen right now (but above and below views are not loaded into
memory)
That's somewhat correct: a ListView will not try to visualize any data that isn't (at least partially) visible. It also 'recycles' views, meaning that any view that isn't currently used to present data to the user and is of the same 'type' as the next data item, may get reused.
Hence you shouldn't rely on persisting data with or make any assumptions about the existence of particular views. In stead, use something that's separate from the views; e.g. the dataset you're visualizing.
Quite often, you'll supply a list of POJOs to a BaseAdapter or ArrayAdapter. You could simply add a boolean to the POJO indicating whether it should animate or not, and change that whenever the animation for that particular item finishes. Alternatively, you could keep track of these values in a separate collection (which is probably the more straightforward approach if you're dealing with a Cursor as data source rather than POJOs).

How to get all children (visible and invisible) from a ListView?

My problem is similar to ListView getChildAt returning null for visible children, but despite searching I cannot find a solution.
I have a ListView with a Scroll. The ListView has 10 items, 7 of which are visible and 3 are hidden by scroll. I also have an external method (out of adapter) that must get all of the children from this ListView (e.g. using getChildAt()).
I need all 10 of the items, but the last 3 are null objects. I've tried code like the following:
getListView().smoothScrollToPosition();
But this doesn't work.
I think that I don't need to post the rest of my code, as the description says everything?

As you have already seen you can't get all the child row views from a ListView simply because a ListView holds only the views for the visible rows(plus some recycled rows but you can't reach those). The correct way to do what you want is to store whatever data in the adapter's data and retrieve it from there.
But the ListView doesn't keep the current values from RadioGroup in
running time.
I've seen that you have some problems with this so I've adapted some old code to build a basic example, code that you can find here.

I don't think so you need to add scroll view for a listView. Scroll automatically works on ListView. Try your application without adding scroll view and I'm sure it'll work as you needed.

The reason those children are null it's because they really do not exist and they will never exist, if only 7 children are on the screen at one time, the system will only create 7 and re-use by passing the convertView back to the adapter getView() method.
If you want to grab information regarding your whole dataset you should search on the dataset itself, instead of the views on the screen. E.g. if it's an ArrayAdapter, loop the array; if it's a CursorAdapter, loop the cursor; etc.

The non-visible children of a listView don't actually exist. When they become visible, one of the redundant views is recycled or a new view is generated. So you can't actually access all the views. Why do you want to? Whatever changes you want to make should be made to the data that populates the views rather than the views themselves.

There are a few point that you need to take care of:
1. List view provides inbuilt scroll functionality, So don't use Scroll view. It will only mess up things.
2. List view doesn't contain ALL the children. When you scroll it, it creates only visible items on run time.
3. If you want to get all the children altogether, Better keep an ArrayList of the child objects that your list has. You can add or remove children to this ArrayList as per requirement.

Is there a way to call BaseAdapter.notifyDataSetChanged() on a single object?

Is there a way to call BaseAdapter.notifyDataSetChanged() on a single element in the adapter.
What I am trying to do is update the data and reflect those changes in the containing ListView. The problem is that sometimes the change is so small that it seems ridiculous that I have to refresh the whole view rather than the single item in the view that has been updated.

I am not aware of such method. If it's really important, you can always find individual item view to update. But I don't think that it worth it as Android is pretty efficient in updating list views. So it will not do much extra work (definitelly not going beyond items currently visible on the screen).