另一个父回收者视图中的回收者视图

Question

Is it possible that I can use a recycler view inside another recycler view ?

My requirements are to show multiple Lists in a screen :

• Vertical List of 3 Items

• Horizontal List of 10 Items

• Vertical List of 5 Expandable Items

• Again Horizontal List of 5 Items

So, I was thinking to have a MultiRecylerAdapter, which would hold adapters for other recyler views inside.

Answer 1

I found the solution.

We can insert the recycler view ( either vertical or horizontal) inside any other recyclerview but default LinearLayoutManager does not support wrap_content height of embedded recycler view.

To support the wrap_content, we should use CustomLinearLayoutManager for the same.

 public class CustomLinearLayoutManager extends LinearLayoutManager {

 public CustomLinearLayoutManager(Context context, int orientation, boolean 
    reverseLayout)    {
    super(context, orientation, reverseLayout);
}

private int[] mMeasuredDimension = new int[2];

@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                      int widthSpec, int heightSpec) {
    final int widthMode = View.MeasureSpec.getMode(widthSpec);
    final int heightMode = View.MeasureSpec.getMode(heightSpec);
    final int widthSize = View.MeasureSpec.getSize(widthSpec);
    final int heightSize = View.MeasureSpec.getSize(heightSpec);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {


        if (getOrientation() == HORIZONTAL) {

            measureScrapChild(recycler, i,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    heightSpec,
                    mMeasuredDimension);

            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
            }
        } else {
            measureScrapChild(recycler, i,
                    widthSpec,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    mMeasuredDimension);
            height = height + mMeasuredDimension[1];
            if (i == 0) {
                width = mMeasuredDimension[0];
            }
        }
    }
    switch (widthMode) {
        case View.MeasureSpec.EXACTLY:
            width = widthSize;
        case View.MeasureSpec.AT_MOST:
        case View.MeasureSpec.UNSPECIFIED:
    }

    switch (heightMode) {
        case View.MeasureSpec.EXACTLY:
            height = heightSize;
        case View.MeasureSpec.AT_MOST:
        case View.MeasureSpec.UNSPECIFIED:
    }

    setMeasuredDimension(width, height);
}

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {
    View view = recycler.getViewForPosition(position);
    recycler.bindViewToPosition(view, position);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                getPaddingLeft() + getPaddingRight(), p.width);
        int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                getPaddingTop() + getPaddingBottom(), p.height);
        view.measure(childWidthSpec, childHeightSpec);
        measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
        measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
        recycler.recycleView(view);
      }
   }
}

Answer 2

UPDATE March 2016

By Android Support Library 23.2.1 of a support library version. So all WRAP_CONTENT should work correctly.

Please update version of a library in gradle file.

  compile 'com.android.support:recyclerview-v7:23.2.1'

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 be required to call

      setAutoMeasureEnabled(true)

Fixed bugs related to various measure-spec methods in update

Check http://developer.android.com/intl/es/tools/support-library/features.html#v7-recyclerview

Answer 3

You can use A RecyclerView withing another RecyclerView . But handling this complex situation is not simple.Creating adapter(s) and managing different layout manager seems complex. Better to put the RecyclerView(s) in a ConstraintLayout/CoOrdinatorLayout and implement ScrollView. That's much more easier.