Recyclerview - 从下到上重叠项目

Question

I have set the negative margin for items like this:-

ItemDecoration.java

public class ItemDecorator extends RecyclerView.ItemDecoration {
    private final int mSpace;

    public ItemDecorator(int space) {
        this.mSpace = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view);
        if (position != 0)
            outRect.top = mSpace;
    }
}

MainActivity.java

recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.addItemDecoration(new ItemDecorator(-80));

This causes top item to stack lowest and next item after the top item overlaps it. I want top item to overlap its next item and so on.

Current View

Required View

Answer 1

Try this way and render your recycler view in reverse direction.

LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setReverseLayout(true);
        layoutManager.setStackFromEnd(true);
        recyclerView.setLayoutManager(layoutManager);

Here is the working example GitHub Link

Answer 2

As of 2020 there is new interface ChildDrawingOrderCallback . It defines the order of drawing elements in recycler view. Can be used like so:

class BackwardsDrawingOrderCallback : RecyclerView.ChildDrawingOrderCallback {
    override fun onGetChildDrawingOrder(childCount: Int, i: Int) = childCount - i - 1
}

And then

recyclerView.setChildDrawingOrderCallback(BackwardsDrawingOrderCallback())

So there is no need to set neither reverse order nor stack from end anymore.

Answer 3

You can create overlapping Ite Decorator by using: Check this link

class OverlappingItemDecoration : RecyclerView.ItemDecoration() {
    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        if (parent.getChildAdapterPosition(view) != RecyclerView.NO_POSITION) {
            outRect.set(0, 0, 0, - 60)
        }
    }
}

Answer 4

The easiest way to achieve overlap is using margin with minus values inside recycler view item like so:

image_item.xml

<com.google.android.material.imageview.ShapeableImageView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/authorIV"
    android:layout_width="35dp"
    android:layout_height="35dp"
    android:layout_marginStart="-8dp"
    android:scaleType="centerCrop"
    android:src="@drawable/ic_default_avatar"
    app:roundPercent="50" />

Answer 5

Try overriding this method.

@Override
public int getItemViewType(int position) {
    return super.getItemViewType(position);
}