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how to set RecyclerView vertical divider with GridLayoutManager same as horizontal vertical

I have a RecyclerView set to a vertical GridLayoutManager
shelfRecyclerView.setLayoutManager(new GridLayoutManager(getContext(),2));
elements inside the recyclerview have fixed width and height using sdp so the horizontal divider width is fixed too.
is there any way to get the width of the horizontal divider and set the vertical divider width as the same as that?

You can achieve this by implementing a custom ItemDecoration which adds equal horizontal and vertical space to each item.
Here are some samples to get you started
Decorating RecyclerView (with GridLayoutManager) to display divider between items
https://gist.github.com/UweTrottmann/c6344c32aa61d1bec5a6

How to create a horizontal list view or recycler view with fixed size by changing the width of its items

I'm beginner in Android Development and trying to create a display of items in such a way that the size of these varieties according to the quantity, as they have done in this app. Any suggestions?
Screenshot 1
Screenshot 2

LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager​.​HORIZONTAL​, false);
RecyclerView myList = (RecyclerView) findViewById​(​R​.​id​.​my_recycler_view​);
myList​.​setLayoutManager​(​layoutManager​);

So according to your question you have to add weight to the child elements which you can be given from parent layout like ex: recyclerview weight 3, and its item weight 1 each(if you have 3 items and fit in the width with margins on either sides) and consider to assign 3 to 6 elements in the width of the screen with horizontal scrolling
mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, true));
check here how to set weights for the views How to set layout_weight attribute dynamically from code?

Recycler view with wrap content items horizontal and vertical scroll

hi i want to make a recycler view to take items horizontal as many as the screen fit but with vertical scroll like this image as example
I try with StaggeredGridLayoutManager but it must specify the number of column want the column take as screen size any help will be good

You can use FlexLayoutManager for this kind of design FlexLayout
Here is a example snippet to use FlexLayoutManager in RecycleView
RecyclerView recyclerView = (RecyclerView) context.findViewById(R.id.recyclerview);
FlexboxLayoutManager layoutManager = new FlexboxLayoutManager(context);
layoutManager.setFlexDirection(FlexDirection.COLUMN);
layoutManager.setJustifyContent(JustifyContent.FLEX_END);
recyclerView.setLayoutManager(layoutManager);
Their are many attributes to use FlexLayout Go through the documents on github

As Burhanuddin Rashid commented, you should use the FlexBoxLayout. It has a LayoutManager for RecyclerViews, so the additional code will be minimal.
https://github.com/google/flexbox-layout#flexboxlayoutmanager-within-recyclerview

Horizontal list view in Android?

Looking for a horizontal list view GUI componnet in Android similar to UICollectionView in iOS. I trid ListView but was not able to set up to scroll it horizontally.
I need only one line, so no grid like multi line 'table'. I know about TableLayout and GridLayout. Which one is more proper for my purpose?
Looking for not a 3rd party solution but a standard Android one without loading in and library.

You should be using the RecyclerLayout, which allows you to specify your own LayoutManager (then you can specify a horizontal one, or a vertical one, or a grid one, or...)
Here is a good SO with a simple example: How to build a Horizontal ListView with RecyclerView?

You can use RecycleView and add horizontal layoutmanager
RecyclerView listView= (RecyclerView)findViewById(R.id.hlistview);
LinearLayoutManager layoutManager=new LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false);
listView.setLayoutManager(layoutManager);
and in xml
<android.support.v7.widget.RecyclerView
android:id="#+id/hlistview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="30dp"/>

How to center RecyclerView in the center (and without scrolling) when possible?

This is a short question:
Suppose I have a RecyclerView that has undefined number of items, what should I do to it, so that if there is a small number of items that (all) can fit the screen, they will be centered and the user won't be able to scroll ?
Of course, if there are too many items, that cannot fit the screen, I would like to have the RecyclerView to show them all as normal (from the beginning to how much it can show, and allow to scroll).
To understand what I mean, I think such a thing is possible when using ScrollView (or HorizontalScrollView if in horizontal), together with a LinearLayout that sets the gravity to be centered .

OK, I think I've found a way:
first, we wait for the RecyclerView to finish its layout process, as I've found about here .
Then, you need to check which child views are shown (available in the LayoutManager that you use), and look at the first and last ones.
If both of them are exactly the same as those that of the total items, it means all needed views are shown, so I can add margins on both sides of the RecyclerView (or padding on its container), according to the space that's left.

I found one complicate way to achieve that.
Main concept: set the height of RV dynamicly in code
RecyclerView rv= (RecyclerView) findViewById(R.id.rv);
rv.setAdapter(new MySlideUpAdapter());
rv.setLayoutManager(new LinearLayoutManager(this));
ViewGroup.LayoutParams layoutParams = rv.getLayoutParams();
layoutParams.height=100;
rv.setLayoutParams(layoutParams);
You may need to calculate the RV's height by childcount*childheight to get pricise value. And don't forget to compare the height to the Parent Layout height, make sure RV's height is less than its Parent Layout height.
Here is my Layout
<RelativeLayout...>
<android.support.v7.widget.RecyclerView
android:id="#+id/rv"
android:layout_centerInParent="true"
android:layout_width="match_parent"
<-height will be changed in code, ignore the 50dp->
android:layout_height="50dp">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>