滚动时，“回收者”视图项会设置动画

Question

I found and research many way and to custom recycler view item animate when scrolling (space between every item will stretch when scrolling) like this gif , even I referred to many related library such as recyclerview-animators or RecyclerViewItemAnimators or creating Animation for each holder onBindViewHolder(). However, all ways above just create animation in the first time load view, can not implement like what animation I want to create. So anyone has done something like that, please help me to resolve that problem. Thank you so much.

EDIT:

I tried to implement OnScrollListener method as @Android recommended. But it do not work properly. This code below show how I implemented them:

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
                int lastPosition = layoutManager.findLastCompletelyVisibleItemPosition();
                int firstPosition = layoutManager.findFirstCompletelyVisibleItemPosition();
                for (int i = firstPosition; i <= lastPosition; i++) {
                    if (dy < 0) {
                        AnimationUtils.animate(recyclerView.findViewHolderForAdapterPosition(i), false);
                    } else {
                        AnimationUtils.animate(recyclerView.findViewHolderForAdapterPosition(i), true);
                    }
                }
            }
        }); 

public class AnimationUtils { public static void animate(RecyclerView.ViewHolder viewHolder, boolean isGoDown){ ObjectAnimator translateY = ObjectAnimator.ofFloat(viewHolder.itemView, "translationY", isGoDown == true ? 300 : -300, 0); translateY.setDuration(300); translateY.setInterpolator(new DecelerateInterpolator(2f)); translateY.start(); } }

Answer 1

You can animate RecyclerView item like this.
All you need is, to write an animate method and call that method in onBindViewHolder() method.

Here is a example for Fading the RecyclerView item

Method

public void setFadeAnimation(View view) {
    AlphaAnimation anim = new AlphaAnimation(0.0f, 1.0f);
    anim.setDuration(500);
    view.startAnimation(anim);
}

Call this method

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

    setFadeAnimation(holder.itemView);
    ........

}

Answer 2

This is the animation example.

You define the lastPosition

private int lastPosition = -1;

private void setAnimation(View viewToAnimate, int position) {

    if (position > lastPosition) {
        Animation animation = AnimationUtils.loadAnimation(context, android.R.anim.slide_in_left);
        animation.setDuration(1000);
        viewToAnimate.startAnimation(animation);
        lastPosition = position;
    } else if ( position < lastPosition) {
        Animation animation = AnimationUtils.loadAnimation(context, android.R.anim.slide_in_left);
        viewToAnimate.startAnimation(animation);
        lastPosition = position;
    }
}

And then only you call the method onBindViewHolder

setAnimation(viewHolder.itemView, position);