This is an example of how it could have been done previously in the ListView
class, using the divider and dividerHeight parameters:
<ListView android:id="@+id/activity_home_list_view" android:layout_width="match_parent" android:layout_height="match_parent" android:divider="@android:color/transparent" android:dividerHeight="8dp"/>
However, I don't see such possibility in the RecyclerView
class.
<android.support.v7.widget.RecyclerView android:id="@+id/activity_home_recycler_view" android:layout_width="match_parent" android:layout_height="match_parent" android:scrollbars="vertical"/>
In that case, is it ok to define margins and/or add a custom divider view directly into a list item's layout or is there a better way to achieve my goal?
If you just want to add equal spacing and want to do it in XML, just set padding to your RecyclerView and equal amount of layoutMargin to the item you inflate into your RecyclerView , and let the background color determine the spacing color.
margin); int marginTopPx = (int) (marginTopDp * getResources(). getDisplayMetrics(). density + 0.5f); layoutParams. setMargins(0, marginTopPx, 0, 0); recyclerView.
Try to use cardElevation=0dp. This should remove the extra spacing between recyclerview items.
Add divider to your Recyclerview:ItemDecoration dividerItemDecoration = new DividerItemDecorator(ContextCompat. getDrawable(context, R. drawable. divider)); recyclerView.
October 2016 Update
The version 25.0.0 of Android Support Library introduced the DividerItemDecoration
class:
DividerItemDecoration is a RecyclerView.ItemDecoration that can be used as a divider between items of a
LinearLayoutManager
. It supports bothHORIZONTAL
andVERTICAL
orientations.
Usage:
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(), layoutManager.getOrientation()); recyclerView.addItemDecoration(dividerItemDecoration);
Previous answer
Some answers either use methods that have since become deprecated, or don't give a complete solution, so I tried to do a short, up-to-date wrap-up.
Unlike ListView
, the RecyclerView
class doesn't have any divider-related parameters. Instead, you need to extend ItemDecoration
, a RecyclerView
's inner class:
An
ItemDecoration
allows the application to add a special drawing and layout offset to specific item views from the adapter's data set. This can be useful for drawing dividers between items, highlights, visual grouping boundaries and more.All
ItemDecorations
are drawn in the order they were added, before the item views (inonDraw()
) and after the items (in onDrawOver(Canvas
,RecyclerView
,RecyclerView.State)
.
Vertical
spacing ItemDecoration
Extend ItemDecoration
, add a custom constructor which takes space height
as a parameter and override the getItemOffsets()
method:
public class VerticalSpaceItemDecoration extends RecyclerView.ItemDecoration { private final int verticalSpaceHeight; public VerticalSpaceItemDecoration(int verticalSpaceHeight) { this.verticalSpaceHeight = verticalSpaceHeight; } @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { outRect.bottom = verticalSpaceHeight; } }
If you don't want to insert space below the last item, add the following condition:
if (parent.getChildAdapterPosition(view) != parent.getAdapter().getItemCount() - 1) { outRect.bottom = verticalSpaceHeight; }
Note: you can also modify outRect.top
, outRect.left
and outRect.right
properties for the desired effect.
ItemDecoration
Extend ItemDecoration
and override the onDraw()
method:
public class DividerItemDecoration extends RecyclerView.ItemDecoration { private static final int[] ATTRS = new int[]{android.R.attr.listDivider}; private Drawable divider; /** * Default divider will be used */ public DividerItemDecoration(Context context) { final TypedArray styledAttributes = context.obtainStyledAttributes(ATTRS); divider = styledAttributes.getDrawable(0); styledAttributes.recycle(); } /** * Custom divider will be used */ public DividerItemDecoration(Context context, int resId) { divider = ContextCompat.getDrawable(context, resId); } @Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) { int left = parent.getPaddingLeft(); int right = parent.getWidth() - parent.getPaddingRight(); int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { View child = parent.getChildAt(i); RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams(); int top = child.getBottom() + params.bottomMargin; int bottom = top + divider.getIntrinsicHeight(); divider.setBounds(left, top, right, bottom); divider.draw(c); } } }
You can either call the first constructor that uses the default Android divider attributes, or the second one that uses your own drawable, for example drawable/divider.xml:
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <size android:height="1dp" /> <solid android:color="#ff992900" /> </shape>
Note: if you want the divider to be drawn over your items, override the onDrawOver()
method instead.
To use your new class, add VerticalSpaceItemDecoration
or DividerSpaceItemDecoration
to RecyclerView
, for example in your fragment's onCreateView()
method:
private static final int VERTICAL_ITEM_SPACE = 48; private RecyclerView recyclerView; private LinearLayoutManager linearLayoutManager; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_feed, container, false); recyclerView = (RecyclerView) rootView.findViewById(R.id.fragment_home_recycler_view); linearLayoutManager = new LinearLayoutManager(getActivity()); recyclerView.setLayoutManager(linearLayoutManager); //add ItemDecoration recyclerView.addItemDecoration(new VerticalSpaceItemDecoration(VERTICAL_ITEM_SPACE)); //or recyclerView.addItemDecoration(new DividerItemDecoration(getActivity())); //or recyclerView.addItemDecoration( new DividerItemDecoration(getActivity(), R.drawable.divider)); recyclerView.setAdapter(...); return rootView; }
There's also Lucas Rocha's library which is supposed to simplify the item decoration process. I haven't tried it though.
Among its features are:
Just add
recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), DividerItemDecoration.VERTICAL));
Also you may need to add the dependencyimplementation 'com.android.support:recyclerview-v7:28.0.0'
For customizing it a little bit you can add a custom drawable:
DividerItemDecoration itemDecorator = new DividerItemDecoration(getContext(), DividerItemDecoration.VERTICAL); itemDecorator.setDrawable(ContextCompat.getDrawable(getContext(), R.drawable.divider));
You are free to use any custom drawable, for instance:
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <solid android:color="@color/colorPrimary"/> <size android:height="0.5dp"/> </shape>
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