Develop Reference

LinearLayout in a RecyclerView doesn't scroll

Here is what I am trying to do:
What is the simplest way to create rows that scroll together and are composed of variable sized clickable Views with the same height on Android
Basically create variable width columns that have the same width in every row. Also need to add, delete and add listeners. Seems like a fairly simple task, but I am finding Android's GUI library a lot harder to figure out than Java's and WPF's GUI library.
Here is my RecyclerView:
public class MainActivity extends AppCompatActivity {
private RecyclerView ampRecyclerView;
private RecyclerView.Adapter ampAdapter;
private RecyclerView.LayoutManager ampLayoutManager;
List<FunctionView> myDataset = new ArrayList<FunctionView>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setUpRecyclerView();
}
private void setUpRecyclerView() {
LinearLayout linearLayout = findViewById(R.id.main_ll);
linearLayout.setWillNotDraw(false);
ampRecyclerView = (RecyclerView) findViewById(R.id.AmpRecyclerView);
// use a linear layout manager
ampLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
ampRecyclerView.setLayoutManager(ampLayoutManager);
myDataset.add(new FunctionView(this));
myDataset.add(new FunctionView(this));
myDataset.add(new FunctionView(this));
// specify an adapter
ampAdapter = new MainActivityAdapter(myDataset, 1);
ampRecyclerView.setAdapter(ampAdapter);
}
}
My adapter
class MainActivityAdapter extends RecyclerView.Adapter<MainActivityAdapter.FunctionViewHolder> {
private List<FunctionView> views = new ArrayList<FunctionView>();
private List<LinearLayout> llViews = new ArrayList<>();
private int rows;
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public static class FunctionViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public LinearLayout linearLayout;
public FunctionViewHolder(LinearLayout v) {
super(v);
linearLayout = v;
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public MainActivityAdapter(List<FunctionView> myDataset, int rows) {
views = myDataset;
this.rows = rows;
}
// Create new views (invoked by the layout manager)
#Override
public MainActivityAdapter.FunctionViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
LinearLayout linearLayout = (LinearLayout) LayoutInflater.from(parent.getContext())
.inflate(R.layout.function_holder, parent, false);
llViews.add(linearLayout);
MainActivityAdapter.FunctionViewHolder vh = new MainActivityAdapter.FunctionViewHolder(linearLayout);
return vh;
}
// Replace the contents of a view (invoked by the layout manager)
#Override
public void onBindViewHolder(MainActivityAdapter.FunctionViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
int width = 0;
for(FunctionView fv : views){
holder.linearLayout.addView(fv);
width += fv.getWidth();
}
holder.linearLayout.setMinimumWidth(width);
//TODO set the data
// holder.functionView = views.get(position);
}
// Return the size of your dataset (invoked by the layout manager)
#Override
public int getItemCount() {
return rows;
}
I know there are glaring design flaws. I am trying to get the scrolling working first, because every layout I try doesn't work how I'd like.
Here is the layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_ll"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/AmpRecyclerView"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
and the holder:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="horizontal"
android:isScrollContainer="true"
android:nestedScrollingEnabled="true"
>
</LinearLayout>

as you said there are glaring design flaws, but you need to change the android:layout_height to wrap_content and android:layout_width to match_Parent.
if your item's hight is match_parent then your inner layout's hight becomes the recyclerview's hight then there is no room for other items so there will be no scrolling.
also, put something like a textView in it to be able to see the items.
another note, the name is supposed to be item not holder. holder is related to ViewHolder which is a totally different thing. you can name it according to your activity for example if Your activity name is MainActivity so your activity layout is activity_main, then you can call the inner layouts item_main
I recommend watching a tutorial on youtube or read an article from medium or anywhere (you can simply just google android recyclerview example) to learn the basics.
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<TextView
android:id="#+id/txt_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="SAMPLE"
android:layout_marginStart="5dp"
android:layout_marginEnd="5dp"
android:layout_marginTop="20dp"
android:layout_marginBottom="20dp"
android:textSize="30sp"
/>
</LinearLayout>

How do I not recycle only the first 2 views of my recyclerview or any items?

I am using a recyclerview for displaying and broadcasting videos of users. However, when I scroll through the recycler view, I see my first view, which has my video gets recycled hence why it's not visible to other users. Is there a way I can make sure that the first view is not recycled so I dont have to worry about my video view getting resetrecycled every single time I scroll through my list?
Here's my code :
In my fragment...
...
<android.support.v7.widget.RecyclerView
android:id="#+id/videoList"
android:layout_width="0dp"
android:layout_height="0dp"
android:visibility="invisible"
app:layout_constraintBottom_toTopOf="#+id/myButtonContainer"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/myoldContainer">
...
and the corresponding adapter...
public class GroupAdapter extends RecyclerView.Adapter<GroupAdapter.myViewHolder> {
private CopyOnWriteArrayList<Person> persons;
private Context mContext;
public GroupAdapter(#NonNull final CopyOnWriteArrayList<Person> persons , Context context) {
this.persons = persons;
this.mContext= context;
for (Person person : this.persons) {
//get names
}
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
final View layout = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_person, parent, false);
final MyViewHolder viewHolder = new MyViewHolder(layout);
return viewHolder;
}
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
final Person person = person.get(position);
final Participant participant = person.getParticipant();
if (person.getName() != null) {
holder.personName.setText(person.getName());
}
if (person.getImage() != null) {
holder.personImage.setImageBitmap(person.getImage());
} else {
holder.personImage.setImageResource(R.drawable.default_profile);
}
holder.personImage.setVisibility(View.INVISIBLE);
holder.personImage.setVisibility(View.VISIBLE);
final VideoView videoView;
if (participant.isMe) {
videoView = participant.videoStreamer.videoView;
} else {
videoView = participant.videoPlayer.videoView;
}
if (holder.personVideo.getChildCount() != 0) {
holder.personVideo.removeAllViews();
}
if (videoView.getParent() != null) {
ViewGroup parent = (ViewGroup) videoView.getParent();
parent.removeView(videoView);
}
holder.personVideo.addView(videoView, myViewHolder.videoLayoutParams);
if (person.isVideoPaused()) {
holder.personVideo.setVisibility(View.INVISIBLE);
holder.personImage.setVisibility(View.VISIBLE);
} else {
holder.personVideo.setVisibility(View.VISIBLE);
holder.personImage.setVisibility(View.INVISIBLE);
}
}
#Override
public int getItemCount() {
return persons.size();
}
public static final class MyViewHolder extends RecyclerView.ViewHolder {
#BindView(R.id.personVideo)
public ViewGroup personVideo;
#BindView(R.id.personImage)
public ImageView personImage;
#BindView(R.id.personName)
public TextView personName;
protected static FrameLayout.LayoutParams videoLayoutParams = new FrameLayout.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT
);
public MyViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
}
}
Here's how I am setting it in my fragment:
LinearLayoutManager manager = new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false);
videoAdapter = new VideoAdapter(myHelper.getPeople(), getContext());
videoList.setLayoutManager(manager);
videoList.setAdapter(videoAdapter);
item_person:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_marginTop="0dp"
android:background="#drawable/person_border"
xmlns:app="http://schemas.android.com/apk/res-auto">
<RelativeLayout
android:id="#+id/personContainer"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="1:1"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent">
<FrameLayout
android:id="#+id/personVideo"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/black" />
<ImageView
android:id="#+id/personImage"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/black"
android:src="#drawable/default_profile" />
<TextView
android:id="#+id/personName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#AA555555"
android:gravity="center_horizontal|bottom"
android:textColor="#color/green"
android:textSize="12sp"
android:lines="1"
android:ellipsize="end"
tools:text="androiduser#gmail.com"
android:layout_alignParentBottom="true" />
</RelativeLayout>
</android.support.constraint.ConstraintLayout>
fragment with recycle view: xml
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<RelativeLayout>
....
</RelativeLayout>
<include containers>...</include>
...
<android.support.v7.widget.RecyclerView
android:id="#+id/personList"
android:layout_width="0dp"
android:layout_height="0dp"
android:visibility="invisible"
>
</android.support.v7.widget.RecyclerView>
</android.support.constraint.ConstraintLayout>

I don't think that "not recycling" the video view will actually stop it from being destroyed when you scroll. It's not the recycling is the problem but the view unbinding.
I think such complex component such as VideoView should not be inside the RecyclerView at all.. You can try adding it as a static content on top, which most likely will solve the issue. You can use a NestedScrollView for that. Take a look here: Recyclerview inside scrollview- How to scroll whole content?
If you still think you want to keep it in the RecyclerView and disable the recycling, do the following.
Create a separate view type for your video view items. Here is an example:
https://stackoverflow.com/a/26573338/3086818. Treat your video view item as a header view from the example.
Once you do this, there is a RecycledViewPool class which manages the recycling of items inside a RecyclerView. You can tell it which views to recycle and which not. By default it recycles all views. To disable recycling for your video view items use your new view type like this:
recyclerView.getRecycledViewPool().setMaxRecycledViews(TYPE_VIDEO_VIEW, 0);
where TYPE_VIDEO_VIEW is the new type that you created using the previous example. The number 0 tells the RecyclerView how many items to recycle - in this case it's 0, meaning "do not recycle". More info about this here: https://stackoverflow.com/a/36313437/3086818.
I hope this helps.. Good luck!

The answer is yes, you can actually do that.
Since you said "The first item" so you simply add a check.
if(position == 0)
{
holder.setIsRecyclable(false); //This line prevents the row from recycling
}

scrollTo() for horizontalScrollView not working

I inflate another layout to appear below some view in my current layout.
This is done like this:
LayoutInflater vi = (LayoutInflater) getActivity().getApplicationContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rootView = vi.inflate(R.layout.horizontal_scroll_view, null);
horizontalScrollView = (HorizontalScrollView) rootView.findViewById(R.id.hsv_suggestions_scroll_view);
LinearLayout suggestionsContainer = (LinearLayout) horizontalScrollView.findViewById(R.id.ll_suggestions_container);
and I can confirm that it appears in the right place since I add some Views in it after a while and they all appear.
The layout I inflate is :
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/hsv_suggestions_scroll_view"
android:scrollbars="none" android:layout_gravity="center_horizontal"
android:paddingTop="16dp" android:fillViewport="true"
android:layout_width="match_parent" android:layout_height="wrap_content">
<LinearLayout
android:id="#+id/ll_suggestions_container"
android:gravity="center_horizontal" android:orientation="horizontal"
android:layout_width="wrap_content" android:layout_height="wrap_content">
</LinearLayout>
just a HorizontalScrollView with a LinearLayout as a child.
The Views I add later are all of them TextViews.
Now after a user action (write some text on an editText) I'm trying to scroll to that View and highlight it. Highlight works. What does not work is scroll.
I have tried :
horizontalScrollView.postDelayed(new Runnable() {
#Override
public void run() {
horizontalScrollView.smoothScrollTo(scrollTo, 0);
}
}, 300);
where variable scrollTo is what I get when I apply getLeft() to the View I wanna scroll to. I can confirm that it takes various values.
Anyone can help me with that ?

Got a similar issue.
I guess the root cause is that the UI was not yet rendered at that moment, causing the scroll not to work properly.
I just had to wrap my call to smoothScrollTo into .post as follows:
mScrollView.post(new Runnable() {
#Override
public void run() {
mScrollView.smoothScrollTo(xxx, yyy);
}
});
Notice that I do a post directly on the scrollView to make sure it is executed after it is being rendered. For example, doing a getActivity().runOnUIThread() would not work in my case.

Switch to using a RecyclerView with a LinearLayoutManager with orientation set to Horizontal. Like this:
scroll_view.xml
<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/scrollView"
android:scrollbars="none"
android:layout_gravity="center_horizontal"
android:paddingTop="16dp"
android:fillViewport="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"
android:orientation="horizontal">
<LinearLayout
android:id="#+id/scrollContainer"
android:gravity="center_horizontal"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</android.support.v7.widget.RecyclerView>
Note: the layoutManager tag is required here for the layout to inflate. After it's inflated, we're going to set it programatically as well because otherwise we'll get an exception because the RecyclerView basically disposes of it before it's done with it.
OptionAdapter.java
public class OptionAdapter extends RecyclerView.Adapter<OptionAdapter.OptionHolder> {
private Context context;
private LayoutInflater inflater;
private ArrayList<String> options;
public OptionAdapter(Context context) {
this.context = context;
this.inflater = LayoutInflater.from(context);
options = new ArrayList<>();
}
#Override
public OptionHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new OptionHolder(inflater.inflate(R.layout.textview, parent, false));
}
#Override
public void onBindViewHolder(OptionHolder holder, int position) {
String option = options.get(position);
((TextView) holder.itemView).setText(option);
}
#Override
public int getItemCount() {
return options != null ? options.size() : 0;
}
public ArrayList<String> getOptions() {
return options;
}
public void addOption(String option, Integer index) {
if (index != null && index <= options.size()) {
options.add(index, option);
} else {
options.add(option);
}
notifyDataSetChanged();
}
public class OptionHolder extends RecyclerView.ViewHolder {
public OptionHolder(View itemView) {
super(itemView);
}
}
}
text_view.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="match_parent" />
Setting everything up
final LayoutInflater inflater = LayoutInflater.from(this);
final RecyclerView scrollView = (RecyclerView) inflater.inflate(R.layout.scroll_view, container, false);
scrollView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
final OptionAdapter adapter = new OptionAdapter(this);
scrollView.setAdapter(adapter);
container here is whatever view is going to be holding the RecyclerView. In my code, I've got it in a LinearLayout.
Adding a view to the list
adapter.addOption("The Added One", null);
Or if you want to add it to a specific position in the list.
adapter.addOption("The Added One", position);
Scrolling to a specific position
scrollView.smoothScrollToPosition(position);
Scrolling to a specific item in the list
scrollView.smoothScrollToPosition(adapter.getOptions().indexOf("ItemText"));
Hope it works for you!

Instead of smoothScrollTo(), try using scrollTo().
Make sure that your getLeft() is really returning a value > 0;

RecyclerView scrolling issue (Child items far away from each other)

Goodd day.I have simple recycler view with simplest dummy datas for test purpose,thus i have an weird issue to which the google did not find any solution or even an issue at all.On first launch the view is all good but as soon as i start to scrool,the child items are being as far from each other as no one can image...Really very and very far.But the issue is that the actual child items layout parameters are correct,only issue is that i dont know why RecyclerView decides to have each item heaps far away from each other.Please can you give me an help?Posting full code of my RecyclerView.
The view for recyclerView
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context="com.ink.activities.HomeActivity"
tools:showIn="#layout/app_bar_home">
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical" />
</RelativeLayout>
The Adapter.
public class FeedAdapter extends RecyclerView.Adapter<FeedAdapter.ViewHolder> {
private List<FeedModel> feedList;
private Context mContext;
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView title, content;
public ViewHolder(View view) {
super(view);
title = (TextView) view.findViewById(R.id.feedTitle);
content = (TextView) view.findViewById(R.id.feedContent);
}
}
public FeedAdapter(List<FeedModel> feedList, Context context) {
mContext = context;
this.feedList = feedList;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.feed_single_view, parent, false);
return new ViewHolder(itemView);
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
FeedModel feedModel = feedList.get(position);
holder.title.setText(feedModel.getTitle());
holder.content.setText(feedModel.getContent());
// animate(holder);
}
public void animate(RecyclerView.ViewHolder viewHolder) {
final Animation animAnticipateOvershoot = AnimationUtils.loadAnimation(mContext, R.anim.bounce_interpolator);
viewHolder.itemView.setAnimation(animAnticipateOvershoot);
}
#Override
public int getItemCount() {
return feedList.size();
}
}
I guess you won`t need holder as no view initiated with it.
The single child item view of RecyclerView adapter.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground"
app:cardCornerRadius="5dp"
app:cardElevation="10dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/feedTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp"
android:fontFamily="#string/appFont"
android:text="loading...."
android:textColor="#000000"
android:textSize="20sp" />
<TextView
android:id="#+id/feedContent"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/feedTitle"
android:layout_marginLeft="2dp"
android:layout_marginRight="2dp"
android:layout_marginTop="10dp" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
The initiation of actual parameters.
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new FeedAdapter(mFeedModelArrayList, this);
RecyclerView.ItemAnimator itemAnimator = new DefaultItemAnimator();
itemAnimator.setAddDuration(500);
itemAnimator.setRemoveDuration(500);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mRecyclerView.setItemAnimator(itemAnimator);
This code is as simple as it can get and it is important to mention that i am initiation all this inside the default NAVIGATION DRAWER ACTIVITY of android studio (the default templae inside content_main layout).So plaese can you give me any hint about the issue?

You're using
android:layout_width="match_parent"
android:layout_height="match_parent"
on your child item views. As of Support Library 23.2:
The RecyclerView widget provides an advanced and flexible base for creating lists and grids as well as supporting animations. This release brings an exciting new feature to the LayoutManager API: auto-measurement! This allows a RecyclerView to size itself based on the size of its contents. This means that previously unavailable scenarios, such as using WRAP_CONTENT for a dimension of the RecyclerView, are now possible. You’ll find all built in LayoutManagers now support auto-measurement.
Due to this change, make sure to double check the layout parameters of your item views: previously ignored layout parameters (such as MATCH_PARENT in the scroll direction) will now be fully respected.
Change your layout_height to wrap_content if you only want your items to be as large as needed. match_parent means they will be as large as the screen.

How to reduce space between items of RecyclerView in Android?

I have implemented Horizontal RecyclerView for Images. Horizontal navigation work fine but unwanted space is drawn between two items of RecyclerView.
RecyclerView item layout-
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="#+id/imgView"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="#drawable/ic_launcher" />
</LinearLayout>
My RecyclerView layout-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
RecyclerView Setup-
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
HlistViewAdapter adapter = new HlistViewAdapter(pArray);
recyclerView.setAdapter(adapter);
recyclerView.setItemAnimator(new DefaultItemAnimator());
My RecyclerView Adapter-
public class HlistViewAdapter extends RecyclerView.Adapter<HlistViewAdapter.ViewHolder>{
ArrayList<String> pathArray;
public HlistViewAdapter(ArrayList<String> pathArray){
this.pathArray = pathArray;
}
#Override
public HlistViewAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View itemLayoutView = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.hlist_item_layout, null);
// create ViewHolder
ViewHolder viewHolder = new ViewHolder(itemLayoutView);
return viewHolder;
}
#Override
public void onBindViewHolder(HlistViewAdapter.ViewHolder viewHolder, int i) {
viewHolder.imgViewIcon.setImageBitmap(BitmapFactory.decodeFile(pathArray.get(i)));
}
public static class ViewHolder extends RecyclerView.ViewHolder {
public ImageView imgViewIcon;
public ViewHolder(View itemLayoutView) {
super(itemLayoutView);
imgViewIcon = (ImageView) itemLayoutView.findViewById(R.id.imgView);
}
}
#Override
public int getItemCount() {
return pathArray.size();
}
}

edited answer after chat with user
the problem was the size of the images being too different to the different android devices, and the impossibility to stretch them to prevent the empty spaces. given that, i recommend the use of a ViewPager instead of a RecyclerView, having that it will provide the same functionality buth with a better controll on how the imageView will react with different sized images.
http://codetheory.in/android-image-slideshow-using-viewpager-pageradapter/