ItemDecoration - How to create vertical dividers?

user_11110509 0
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I'm trying to create multiple vertical dividers for each ViewHolder in recyclerView but can't figure out how.

Heres my code for working horizontal dividers:

@Override
public void onDrawOver(@NonNull Canvas c, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {


    int left = parent.getPaddingLeft();
    int right = parent.getWidth() - parent.getPaddingRight();

    int count = parent.getChildCount();
    for(int i = 0; i < count; i++){
        View child = parent.getChildAt(i);

        RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

        int top = child.getBottom() + params.bottomMargin;
        int bottom = top + mDivider.getIntrinsicHeight();

        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }
}

drawable divider:

<?xml version="1.0" encoding="utf-8"?>


<size
    android:width="10dp"
    android:height="10dp" />
<solid android:color="@color/standardBlue" />

item-decoration android-recyclerview android
1 Answers

DividerItemDecoration is a RecyclerView.ItemDecoration that can be used as a divider between items of a LinearLayoutManager. It supports both HORIZONTAL and VERTICAL orientations.

Usage:

DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
    layoutManager.getOrientation());
recyclerView.addItemDecoration(dividerItemDecoration);

Previous answer

All ItemDecorations are drawn in the order they were added, before the item views (in onDraw()) and after the items (in onDrawOver(Canvas, RecyclerView, RecyclerView.State).

Vertical spacing ItemDecoration Extend ItemDecoration, add custom constructor which takes space height as a parameter and override 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 desired effect.

Divider ItemDecoration Extend ItemDecoration and override 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 onDrawOver() method instead.

Usage 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;
}
user_7463080
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