[android] RecyclerView expand/collapse items


4 Answers

Not saying this is the best approach, but it seems to work for me.

The full code may be found at: Example code at: https://github.com/dbleicher/recyclerview-grid-quickreturn

First off, add the expanded area to your cell/item layout, and make the enclosing cell layout animateLayoutChanges="true". This will ensure that the expand/collapse is animated:

<LinearLayout
    android:id="@+id/llCardBack"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/white"
    android:animateLayoutChanges="true"
    android:padding="4dp"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tvTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center|fill_horizontal"
        android:padding="10dp"
        android:gravity="center"
        android:background="@android:color/holo_green_dark"
        android:text="This is a long title to show wrapping of text in the view."
        android:textColor="@android:color/white"
        android:textSize="16sp" />

    <TextView
        android:id="@+id/tvSubTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center|fill_horizontal"
        android:background="@android:color/holo_purple"
        android:padding="6dp"
        android:text="My subtitle..."
        android:textColor="@android:color/white"
        android:textSize="12sp" />

    <LinearLayout
        android:id="@+id/llExpandArea"
        android:visibility="gone"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="6dp"
            android:text="Item One" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="6dp"
            android:text="Item Two" />

    </LinearLayout>
</LinearLayout>

Then, make your RV Adapter class implement View.OnClickListener so that you can act on the item being clicked. Add an int field to hold the position of the one expanded view, and initialize it to a negative value:

private int expandedPosition = -1;

Finally, implement your ViewHolder, onBindViewHolder() methods and override the onClick() method. You will expand the view in onBindViewHolder if it's position is equal to "expandedPosition", and hide it if not. You set the value of expandedPosition in the onClick listener:

@Override
public void onBindViewHolder(RVAdapter.ViewHolder holder, int position) {

    int colorIndex = randy.nextInt(bgColors.length);
    holder.tvTitle.setText(mDataset.get(position));
    holder.tvTitle.setBackgroundColor(bgColors[colorIndex]);
    holder.tvSubTitle.setBackgroundColor(sbgColors[colorIndex]);

    if (position == expandedPosition) {
        holder.llExpandArea.setVisibility(View.VISIBLE);
    } else {
        holder.llExpandArea.setVisibility(View.GONE);
    }
}

@Override
public void onClick(View view) {
    ViewHolder holder = (ViewHolder) view.getTag();
    String theString = mDataset.get(holder.getPosition());

    // Check for an expanded view, collapse if you find one
    if (expandedPosition >= 0) {
        int prev = expandedPosition;
        notifyItemChanged(prev);
    }
    // Set the current position to "expanded"
    expandedPosition = holder.getPosition();
    notifyItemChanged(expandedPosition);

    Toast.makeText(mContext, "Clicked: "+theString, Toast.LENGTH_SHORT).show();
}

/**
 * Create a ViewHolder to represent your cell layout
 * and data element structure
 */
public static class ViewHolder extends RecyclerView.ViewHolder {
    TextView tvTitle;
    TextView tvSubTitle;
    LinearLayout llExpandArea;

    public ViewHolder(View itemView) {
        super(itemView);

        tvTitle = (TextView) itemView.findViewById(R.id.tvTitle);
        tvSubTitle = (TextView) itemView.findViewById(R.id.tvSubTitle);
        llExpandArea = (LinearLayout) itemView.findViewById(R.id.llExpandArea);
    }
}

This should expand only one item at a time, using the system-default animation for the layout change. At least it works for me. Hope it helps.

Question

I want to expand/collapse the items of my recyclerView in order to show more info. I want to achieve the same effect of the SlideExpandableListView.

Basically in my viewHolder I have a view that is not visible and I want to do a smooth expand/collapse animation rather than set the visibility to VISIBLE/GONE only. I only need an item to be expanded at a time and it would be cool to have some elevation to show that the item is selected.

It is the same effect of the new Android recent calls history list. The options "CALL BACK" and "DETAILS" are visible only when an item is selected.




Do the following after you set the onClick listener to the ViewHolder class:

@Override
    public void onClick(View v) {
        final int originalHeight = yourLinearLayout.getHeight();
        animationDown(YourLinearLayout, originalHeight);//here put the name of you layout that have the options to expand.
    }

    //Animation for devices with kitkat and below
    public void animationDown(LinearLayout billChoices, int originalHeight){

        // Declare a ValueAnimator object
        ValueAnimator valueAnimator;
        if (!billChoices.isShown()) {
            billChoices.setVisibility(View.VISIBLE);
            billChoices.setEnabled(true);
            valueAnimator = ValueAnimator.ofInt(0, originalHeight+originalHeight); // These values in this method can be changed to expand however much you like
        } else {
            valueAnimator = ValueAnimator.ofInt(originalHeight+originalHeight, 0);

            Animation a = new AlphaAnimation(1.00f, 0.00f); // Fade out

            a.setDuration(200);
            // Set a listener to the animation and configure onAnimationEnd
            a.setAnimationListener(new Animation.AnimationListener() {
                @Override
                public void onAnimationStart(Animation animation) {

                }

                @Override
                public void onAnimationEnd(Animation animation) {
                    billChoices.setVisibility(View.INVISIBLE);
                    billChoices.setEnabled(false);
                }

                @Override
                public void onAnimationRepeat(Animation animation) {

                }
            });
            // Set the animation on the custom view
            billChoices.startAnimation(a);
        }
        valueAnimator.setDuration(200);
        valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator());
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            public void onAnimationUpdate(ValueAnimator animation) {
                Integer value = (Integer) animation.getAnimatedValue();
                billChoices.getLayoutParams().height = value.intValue();
                billChoices.requestLayout();
            }
        });


        valueAnimator.start();
    }
}

I think that should help, that's how I implemented and does the same google does in the recent call view.




I know it has been a long time since the original question was posted. But i think for slow ones like me a bit of explanation of @Heisenberg's answer would help.

Declare two variable in the adapter class as

private int mExpandedPosition= -1;
private RecyclerView recyclerView = null;

Then in onBindViewHolder following as given in the original answer.

      // This line checks if the item displayed on screen 
      // was expanded or not (Remembering the fact that Recycler View )
      // reuses views so onBindViewHolder will be called for all
      // items visible on screen.
    final boolean isExpanded = position==mExpandedPosition;

        //This line hides or shows the layout in question
        holder.details.setVisibility(isExpanded?View.VISIBLE:View.GONE);

        // I do not know what the heck this is :)
        holder.itemView.setActivated(isExpanded);

        // Click event for each item (itemView is an in-built variable of holder class)
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

 // if the clicked item is already expaned then return -1 
//else return the position (this works with notifyDatasetchanged )
                mExpandedPosition = isExpanded ? -1:position;
    // fancy animations can skip if like
                TransitionManager.beginDelayedTransition(recyclerView);
    //This will call the onBindViewHolder for all the itemViews on Screen
                notifyDataSetChanged();
            }
        });

And lastly to get the recyclerView object in the adapter override

@Override
public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);

    this.recyclerView = recyclerView;
}

Hope this Helps.




There is a very simple to use library with gradle support: https://github.com/cachapa/ExpandableLayout.

Right from the library docs:

<net.cachapa.expandablelayout.ExpandableLinearLayout
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:el_duration="1000"
    app:el_expanded="true">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Click here to toggle expansion" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="Fixed height"
        app:layout_expandable="true" />

 </net.cachapa.expandablelayout.ExpandableLinearLayout>

After you mark your expandable views, just call any of these methods on the container: expand(), collapse() or toggle()




Use two view types in the your RVAdapter. One for expanded layout and other for collapsed. And the magic happens with setting android:animateLayoutChanges="true" for RecyclerView Checkout the effect achieved using this at 0:42 in this video






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