How To Add RecyclerView Slide In Animation for New Item

Question

I have a RecyclerView and add items to mCommentArrayList at index 0. I am trying to create a slide-in animation at the top of the view as new items (CardViews) are added to the RecyclerView.

I know there are libraries that can be used, and I have even explored https://github.com/wasabeef/recyclerview-animators. However, the documentation is limited and I am unsure what approach to take.

Note that I add all new items to my mCommentArrayList at index 0 so that they appear at the top of the view. I know there is some work to be done in the adapter, specifically onBindViewHolder(), but I don't know exactly what to put in order to activate the animations.

Where I first call to Firebase to find data to populate the RecyclerView:

    mUpdateRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            setImage(dataSnapshot);
            setQuestion(dataSnapshot);
            createInitialCommentIDArray(dataSnapshot);
            mNumberOfCommentsAtPoll = (int) dataSnapshot.child(COMMENTS_LABEL).getChildrenCount();
            for (int i = 0; i < mNumberOfCommentsAtPoll; i++) {
                String commentID = (String) dataSnapshot.child(COMMENTS_LABEL).child(mCommentIDArrayList.get(i)).child("COMMENT").getValue();
                Log.v("COMMENT_ID", "The comment ID is " + commentID);
                String userID = (String) dataSnapshot.child(COMMENTS_LABEL).child(mCommentIDArrayList.get(i)).child("USER_ID").getValue();
                Log.v("USER_ID", "The user ID is " + userID);
                mCommentArrayList.add(0, new Comments(mUserAvatar, userID, commentID));
                mCommentAdapter.notifyDataSetChanged();
            }

        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });

Subsequent Calls to Firebase on Data Change:

@Override
protected void onStart() {
    super.onStart();
    mUpdateComments = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            mNumberOfCommentsAtPoll = (int) dataSnapshot.getChildrenCount();
            for (DataSnapshot x : dataSnapshot.child(COMMENTS_LABEL).getChildren()) {
                Log.v("DATA_SNAPSHOT", x.toString());
                if (mCommentIDArrayList.contains(x.getKey())) {
                    Log.v("Comment_Already_Added", x.getKey());
                } else {
                    Log.v("Child_Added_Called", "Child Added Called");
                    mCommentIDArrayList.add(x.getKey());
                    String commentID = (String) dataSnapshot.child(COMMENTS_LABEL).child(x.getKey()).child("COMMENT").getValue();
                    Log.v("New_Comment", "The new comment is " + commentID);
                    String userID = (String) dataSnapshot.child(COMMENTS_LABEL).child(x.getKey()).child("USER_ID").getValue();
                    Log.v("New_User_ID", "The new userID is " + userID);
                    mCommentArrayList.add(0, new Comments(mUserAvatar, userID, commentID));
                    mPollCommentsList.getAdapter().notifyItemInserted(0);
                }
            }
        }

Answer 1

Using the library you were talking about (https://github.com/wasabeef/recyclerview-animators) it's very easy to add a SlideInAnimator to your RecyclerView. Just use the following code to set an Animator to your RecyclerView (pick one):

    recyclerView.setItemAnimator(new SlideInDownAnimator());
    recyclerView.setItemAnimator(new SlideInRightAnimator());
    recyclerView.setItemAnimator(new SlideInLeftAnimator());
    recyclerView.setItemAnimator(new SlideInUpAnimator());

Once you have done this the you can simply trigger the animation by calling notifyItemInserted(position) or notifyItemRangeInserted(positionStart, itemCount). These calls will trigger the Animator, calling notifyDatasetChanged() won't.

Triggering the insertion animation:

    recyclerView.getAdapter().notifyItemInserted(position);
    recyclerView.getAdapter().notifyItemRangeInserted(positionStart, itemCount);

Answer 2

Hope this code help's you !

create one animation file animation_from_right.xml

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

<set xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="700"
android:fillAfter="false"
>

<translate
android:interpolator="@android:anim/decelerate_interpolator"
android:fromXDelta="100%p"
android:toXDelta="0"
/>

<alpha
android:fromAlpha="0.5"
android:toAlpha="1"
android:interpolator="@android:anim/accelerate_decelerate_interpolator"
/>

</set>

in Activity

Animation animation = AnimationUtils.loadAnimation(mActivity, R.anim.animation_from_right);
        holder.itemView.startAnimation(animation);

use above code in your Adapter on onBindViewHolder