Develop Reference

Android RecyclerView add horizontal gape in beginning and in ending

I am trying to replicate a view from iOS so that user have same look and feel throughout the android application as well.
I am having a RecyclerView with LinearLayoutManager and horizontal orientation. So far so good.
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"
tools:listitem="#layout/item_recycler_view" />
With the output design:
However, in case of iOS design we have items starting from center however the horizontal view is completely scrollable (meaning the scrolling can be done to full width even if the item loading from center).
I know there is no use of adding padding/margin or using a different view like HorizontalScrollView. How can we obtain such behaviour so that i give nearly same experience to users.
Let me know if there is anything that i can provide to clarify the problem statement.

Quick solution
Add an empty item on the beginning and one on the end of your list, and make your index access account for those two extra items. That should help you get the desired effect.
Not so quick solution
Android allows us to write our own custom Layout Managers for RecyclerView. It comes with three types that will cover most of the user cases:
LinearLayoutManger (For lists in general);
GridLayoutManager (For grids);
StaggeredGridLayoutManager (For grids with items with custom sizes).
I believe you could write one to always start placing the first item on the center of the screen. That will require more work, but it won't mess with your data indexes.
Read this, and this, on how to create custom Layout Managers. Also, take a look at the docs. That should be a good place to start.

There are two ways you could do this. The simplest by far would be to add horizontal padding to your RecyclerView and set the view to not clip based on padding. Something like this:
android:paddingLeft="100dp"
android:paddingRight="100dp"
android:clipToPadding="false"
The other way would be to create an ItemDecoration and add it to your RecyclerView. You could then override the getItemOffsets() method to add a left-hand offset to your first item and a right-hand offset to your last item.
This second approach is better because it won't affect the RecyclerView's scrollbars, but it is a little more complex. Here's an example to get you started:
private static class MyItemDecoration extends RecyclerView.ItemDecoration {
#Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int parentWidth = parent.getWidth();
int childWidth = view.getWidth();
int margin = (parentWidth - childWidth) / 2;
int position = parent.getChildAdapterPosition(view);
outRect.left = position == 0 ? margin : 0;
outRect.right = position == (parent.getAdapter().getItemCount() - 1) ? margin : 0;
}
}

I think the only way will be adding different layout for first and last position in adapter of recyclerview.
It can be done using viewType parameter in createViewHolder(ViewGroup parent, int viewType)

Horizontal RecyclerView with variable item heights not wrapping properly

What I intend to achieve
The item view should occupy the entire height of the item
It could be that the item height is lesser than the height of the tallest item in the recyclerview, in which case it should just stick to the top like in the screenshot above.
The bug I'm running into
As in the screenshot above, views are getting truncated.
What I've tried so far
Initially I went with wrap_content on the recyclerview, now that it is supported. It didn't work when none of the views visible on the screen at the time were the tallest. This makes sense in how the view hierarchy is laid out. How can the height of something which hasn't even been bound to any data yet be calculated if the height is dependent on that data?
Workaround time :S
Instead of trying a custom layoutmanager, I first went with what I felt needed to be done - laying out all item views at the beginning to figure out their height.
There's a progressbar and an animation playing in the upper part of the screen to catch the user's attention while all this happens with recyclerview visibility set to invisible. I use two things, one didn't suffice - I've attached an observer in the adapter's onViewAttached() call and I've used a scroll change listener as well. There's a LinearSnapHelper attached to the recycler view to snap to adjacent (next or previous, depending on the scroll direction) position on scroll.
In this setup,
I'm going to each position in the recyclerview using layoutManager.smoothScrollToPosition()
Getting the child view height using
View currentChildView = binding.nextRv.getChildAt(layoutManager.findFirstCompletelyVisibleItemPosition());
if (currentChildView != null) {
currentChildHeight = currentChildView.getHeight();
}
in scroll change listener on RecyclerView.SCROLL_STATE_IDLE or by passing the height to the view attached observer mentioned above in the adapter's onViewAttachedToWindow()
#Override
public void onViewAttachedToWindow(BindingViewHolder holder) {
if (mObserver != null) {
mObserver.onViewAttached(holder.binding.getRoot().getHeight());
}
}
Storing a maxHeight that changes to the max of maxHeight and new child's height.
As is evident, this is ugly. Plus it doesn't give me the current view's height - onAttached means it's only just attached, not measured and laid out. It is the recycled view, not the view bound to current data item. Which presents problems like the truncation of view illustrated above.
I've also tried wrap_content height on the recycler view and invalidating from recycler's parent till the recycler and the child on scroll coming to SCROLL_STATE_IDLE. Doesn't work.
I'm not sure how a custom layoutmanager can help here.
Can someone guide me in the right direction?

I could not accept #Pradeep Kumar Kushwaha's answer because against one solution, I do not want different font sizes in the list. Consistency is a key element in design. Second alternative he gave couldn't work because with ellipsize I would need to give a "more" button of some sort for user to read the entire content and my text view is already taking a click action. Putting more some place else would again not be good design.
Changing the design with the simple compromise of resizing the recyclerview when the tallest, truncated item comes into focus, it turns into the simple use case of notifyItemChanged(). Even for the attempt I made using the view attached observer and scroll state listener, notifyItemChanged could be used but that approach is just too hacky. This I can live with in both code and design. Here goes the code required.
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
int position = ((LinearLayoutManager) binding.nextRv.getLayoutManager())
.findFirstVisibleItemPosition();
if (position != nextSnippetAdapter.getItemCount() - 1) {
binding.nextRv.getAdapter().notifyItemRangeChanged(position, 2);
} else {
binding.nextRv.getAdapter().notifyItemChanged(position);
}
}
}
For my particular setup, calling for just these two elements works. It can further be optimized so as to call for single element at position + 1 in most cases, and checking and calling for the appropriate one in corner (literal) cases.

Inside your adapter where I can find two cards one on top and another on bottom
How I would have defined my layout is like this:
Cardview1
LinearLayout1 --> orientation vertical
cardview2 (Top card where text is written)
Linearlayout2 (where I can see icons such as like etc)-->orientation horizontal
Now fix the height of Linearlayout2 by setting it to wrap content.
And the height of cardview2 should be 0dp and add weight = 1
Now inside cardview2 add a TextView1 to matchparent in height and width.
Better inside textview1 add ellipsize to end and add max lines
If you want to show all lines try to find autoresizetextview library it can be founded here --> AutoResizeTextView
Hope it helps.

I think the recyclerview can be set to height wrap_content. And the items can be make like height to match_parent.
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layput_height="wrap_content"/>
Item as:
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
// your coode
</androidx.constraintlayout.widget.ConstraintLayout>
I had little more requirement than the question. Even my problem solved in the way.
Remember I am using:
androidx.recyclerview:recyclerview:1.0.0-beta01
dependency for the project

Android equivalent to View.setTranslationX, but to adjust width?

I have been spending hours unsuccessfully trying to adjust the width, height, and offset of a simple view in Android as the result of a button press. I have discovered that setTranslationX and setTranslationY always work; the legacy method of setLayoutParams never works once the view is laid out initially. Calls to requestLayout() and invalidate() similarly produce no results.
I have tried to setLayoutParams within the context of posting a runnable, but this does nothing.
Because setTranslationX always works, I would just use that, but unfortunately there is no equivalent method like setWidth or setHeight.
As you can see in the AOSP, setTranslationX makes a call to invalidateViewProperty, which is a private method of View.
Is there an equivalent method to setTranslationX to adjust a view width or view margin, that presumably triggers invalidateViewProperty, and, by extension, works reliably?
EDIT
While in some situations, setLayoutParams may be expected to work after the initial layout, I am in a situation where setLayoutParams has no effect after the initial layout, but setTranslationX does. My setup is as follows:
Running Android KitKat 4.4
The view in question is MATCH_PARENT for both width, height
The view in question is a child of a RelativeLayout
The view in question is a View class with a simple solid-color background drawable
Here is the view:
<View
android:id="#+id/border"
android:background="#drawable/match_background_border_transparent"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
And here is the (non-working) code meant to dynamically alter its margins, but has no effect. Again, if I call setTranslationX, that always works.
holder.toggleButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
imageBorder.post(new Runnable() {
#Override
public void run() {
RelativeLayout.LayoutParams p = (LayoutParams) imageBorder.getLayoutParams();
p.leftMargin = 20;
p.rightMargin = 20;
p.topMargin = 20;
p.bottomMargin = 20;
imageBorder.setLayoutParams(p);
// imageBorder.setTranslationX does have an effect if I included it here
}
});
}
});

I have determined why setTranslationX was working, but setLayoutParams was not. My views were ultimately descendents of an AdapterView. I was able to programmatically manipulate LayoutParams of the AdapterView and his siblings, but none of the AdapterView's descendents.
Additional research showed that this was a common Android question:
Margin on ListView items in android
Why LinearLayout's margin is being ignored if used as ListView row view
What was confusing was that this view was several levels deep; i.e., it went:
AdapterView -> FrameLayout -> RelativeLayout -> View
Anyhow, I was able to accomplish my programmatic layout goals by wrapping view in another view, and using setPadding.

How to change a header TextView Text when during scrolling of Horizontal scrollView?

I have a horizontal scroll view, I also have a relativelayout as it's child. I am adding child views of this relativelayout dynamically. I have a header text which should be update when I scroll according to respective child views. How can I do this because I am able to get the current focused item in horizontal scroll. Please give me some suggestion or examples which can be helpful for me, thanks..

You should specify an OnTouchListener for your HorizontalScrollView and in it's onTouch() method detect the type of MotionEvent and change your TextView's color to the appropriate

If you are creating this childs dinamically you can set a tag to them with the content you want to show in the header TextView.
//Creating RelativeLayout childs
TextView newChild = new TextView(this).
newChild.setTag(textToShowWhenThisItemIsFocused);
Then if you know which item is focused you just have to get the tag.
// "selected" is the focused view
header.setText((String) selected.getTag());
When to use the second code depends on your implementation. Since you didn't provide any code it's hard to know how to monitor the scroll, but i.e. you could control Touch Events and update the header when the user is moving his finger over the screen (you should also take into account the inertia after the user stops tapping).
EDIT: How to get the focused View
First of all, I barely have experience doing things like this, so I'm not sure if this is going to work or if there are better ways to do it. I'll just tell you the way I would approach this problem.
To be able to know the focused View you need to know the coordinates where this View should be. Since it's an horizontal ScrollView we will need the X coordinate. Since we want the View in the middle of the ScrollView I would do it like this:
private int centerSV;
private ScrollView mScrollView;
...
centerSV = mScrollView.getWidth()/2;
Now we have the center of the ScrollView. Now we need to know which child is in this position:
private int getFocusedChildId(){
for(int i=0; i<mChilds.length; i++){
int childLeftCoord = mChilds[i].getLeft() - mScrollView.getScrollX();
if(childLeftCoord <= centerSV && centerSV <= childLeftCoord + mChilds[i].getWidth())
return mChilds[i].getId();
}
// No view found in the center, maybe ScrollView wasn't full. Return the first one
return mChilds[0].getId();
}
Again, I'm not sure if this is going to work, it's just an idea of how to approach your issue. Also, you should take this into account:
getWidth() and getHeight() of View returns 0

How to bring a view to front without calling bringToFront()?

There is apparently a bug in Android which breaks View.bringToFront.
If I have Views arranged in a GridView and want to bring a View to front by calling bringToFront(), it may get moved to the bottom right position in the GridView.
Something shady is going on there, so I can't use bringToFront(). When I don't call it, everything works fine. But the Views overlap - if I use scale animation to scale up a View, it's partially obscured by the Views to the bottom and to the right.
I've checked out bringToFront's source and it calls parent.bringChildToFront(...)
it's this method
public void bringChildToFront(View child) {
int index = indexOfChild(child);
if (index >= 0) {
removeFromArray(index);
addInArray(child, mChildrenCount);
child.mParent = this;
}
}
it apparently removes the View from itself! Without mercy! Is a ViewGroup so dumb that it can't manage Z-indexes in any other way that shuffling controls around? Obviously when GridView removes its child and then adds it back again, it gets placed at the end of the Grid!
Is there anything I can do to show a View on top of others without resorting to some hacking? One thing that comes to my mind is to create another View above the GridView, which will appear to be above the one I'm trying to bringToFront(), but I don't like this solution.

apparently I missed the android:clipChildren="false" property in GridView. It solves my problem.

Have you tried making the View focusable and just calling requestFocus()?

Calling bringToFront() changes the ordering in the GridView. Try creating an ImageView with an image of the view you want to animate and animate that instead.
Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
view.draw(canvas);
final ImageView imageView = new ImageView(getActivity());
imageView.setImageBitmap(bitmap);
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(view.getWidth() , view.getHeight());
imageView.setLayoutParams(params);
rootview.addView(imageView);
Add an animation listener to your animation and remove the ImageView at the end of the animation.

From API 21 you can call:
view.setZ(float)

If you target API above 21, you can simply add the attribute android:translationZ="xxx dp" to your XML.
Please note that if you add elevation in views like cardview, you go into the Z axis. And if you want a view come to foreground using this way, you just have to make it higher than the elevation you set.
Example : 6 dp elevation in cardview will require a 7dp in the attribute translationZ of the view you want foreground.