activity_comments.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".CommentsActivity">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="@dimen/default_elevation">

        <ImageView
            android:id="@+id/ivLogo"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_gravity="center"
            android:scaleType="center"
            android:src="@drawable/img_toolbar_logo" />
    </android.support.v7.widget.Toolbar>

    <LinearLayout
        android:id="@+id/contentRoot"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/toolbar"
        android:background="@color/bg_comments"
        android:elevation="@dimen/default_elevation"
        android:orientation="vertical">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/rvComments"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:scrollbars="none" />

        <LinearLayout
            android:id="@+id/llAddComment"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/bg_comments"
            android:elevation="@dimen/default_elevation">

            <EditText
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1" />

            <Button
                android:id="@+id/btnSendComment"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Send" />
        </LinearLayout>
    </LinearLayout>
</RelativeLayout>

bg_comment_avatar.xml

<?xml version="1.0" encoding="utf-8"?>
<!--drawable/bg_comment_avar.xml-->
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="#999999" />
</shape>

CommentsActivity_enter_transition.java

public class CommentsActivity extends ActionBarActivity {
    public static final String ARG_DRAWING_START_LOCATION = "arg_drawing_start_location";

    @InjectView(R.id.toolbar)
    Toolbar toolbar;
    @InjectView(R.id.contentRoot)
    LinearLayout contentRoot;
    @InjectView(R.id.rvComments)
    RecyclerView rvComments;
    @InjectView(R.id.llAddComment)
    LinearLayout llAddComment;

    private CommentsAdapter commentsAdapter;
    private int drawingStartLocation;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        //...
        
        drawingStartLocation = getIntent().getIntExtra(ARG_DRAWING_START_LOCATION, 0);
        if (savedInstanceState == null) {
            contentRoot.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                @Override
                public boolean onPreDraw() {
                    contentRoot.getViewTreeObserver().removeOnPreDrawListener(this);
                    startIntroAnimation();
                    return true;
                }
            });
        }
    }

    //...

    private void startIntroAnimation() {
        contentRoot.setScaleY(0.1f);
        contentRoot.setPivotY(drawingStartLocation);
        llAddComment.setTranslationY(100);

        contentRoot.animate()
                .scaleY(1)
                .setDuration(200)
                .setInterpolator(new AccelerateInterpolator())
                .setListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        animateContent();
                    }
                })
                .start();
    }

    private void animateContent() {
        commentsAdapter.updateItems();
        llAddComment.animate().translationY(0)
                .setInterpolator(new DecelerateInterpolator())
                .setDuration(200)
                .start();
    }

    //...

}

CommentsActivity_exit_transition.java

public class CommentsActivity extends ActionBarActivity {
    
    //...

    @Override
    public void onBackPressed() {
        contentRoot.animate()
                .translationY(Utils.getScreenHeight(this))
                .setDuration(200)
                .setListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        CommentsActivity.super.onBackPressed();
                        overridePendingTransition(0, 0);
                    }
                })
                .start();
    }

}

CommentsActivity_items_animations.java

public class CommentsActivity extends ActionBarActivity {

    //...

    private void setupComments() {

        //...

        rvComments.setOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {
                    commentsAdapter.setAnimationsLocked(true);
                }
            }
        });
    }

    @OnClick(R.id.btnSendComment)
    public void onSendCommentClick() {
        commentsAdapter.addItem();
        commentsAdapter.setAnimationsLocked(false);
        commentsAdapter.setDelayEnterAnimation(false);
        rvComments.smoothScrollBy(0, rvComments.getChildAt(0).getHeight() * commentsAdapter.getItemCount());
    }
}

CommentsAdapter.java

public class CommentsAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private Context context;
    private int itemsCount = 0;
    private int lastAnimatedPosition = -1;
    private int avatarSize;

    private boolean animationsLocked = false;
    private boolean delayEnterAnimation = true;

    public CommentsAdapter(Context context) {
        this.context = context;
        avatarSize = context.getResources().getDimensionPixelSize(R.dimen.btn_fab_size);
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        final View view = LayoutInflater.from(context).inflate(R.layout.item_comment, parent, false);
        return new CommentViewHolder(view);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
        runEnterAnimation(viewHolder.itemView, position);
        CommentViewHolder holder = (CommentViewHolder) viewHolder;
        switch (position % 3) {
            case 0:
                holder.tvComment.setText("Lorem ipsum dolor sit amet, consectetur adipisicing elit.");
                break;
            case 1:
                holder.tvComment.setText("Cupcake ipsum dolor sit amet bear claw.");
                break;
            case 2:
                holder.tvComment.setText("Cupcake ipsum dolor sit. Amet gingerbread cupcake. Gummies ice cream dessert icing marzipan apple pie dessert sugar plum.");
                break;
        }

        Picasso.with(context)
                .load(R.drawable.ic_launcher)
                .centerCrop()
                .resize(avatarSize, avatarSize)
                .transform(new RoundedTransformation())
                .into(holder.ivUserAvatar);
    }

    private void runEnterAnimation(View view, int position) {
        if (animationsLocked) return;

        if (position > lastAnimatedPosition) {
            lastAnimatedPosition = position;
            view.setTranslationY(100);
            view.setAlpha(0.f);
            view.animate()
                    .translationY(0).alpha(1.f)
                    .setStartDelay(delayEnterAnimation ? 20 * (position) : 0)
                    .setInterpolator(new DecelerateInterpolator(2.f))
                    .setDuration(300)
                    .setListener(new AnimatorListenerAdapter() {
                        @Override
                        public void onAnimationEnd(Animator animation) {
                            animationsLocked = true;
                        }
                    })
                    .start();
        }
    }

    @Override
    public int getItemCount() {
        return itemsCount;
    }

    public void updateItems() {
        itemsCount = 10;
        notifyDataSetChanged();
    }

    public void addItem() {
        itemsCount++;
        notifyItemInserted(itemsCount - 1);
    }

    public void setAnimationsLocked(boolean animationsLocked) {
        this.animationsLocked = animationsLocked;
    }

    public void setDelayEnterAnimation(boolean delayEnterAnimation) {
        this.delayEnterAnimation = delayEnterAnimation;
    }

    public static class CommentViewHolder extends RecyclerView.ViewHolder {
        @InjectView(R.id.ivUserAvatar)
        ImageView ivUserAvatar;
        @InjectView(R.id.tvComment)
        TextView tvComment;

        public CommentViewHolder(View view) {
            super(view);
            ButterKnife.inject(this, view);
        }
    }
}

FeedAdapter.java

//.. implements View.OnClickListener
public class FeedAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> implements View.OnClickListener {

    private OnFeedItemClickListener onFeedItemClickListener;

    //..

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
        //...
        holder.ivFeedBottom.setOnClickListener(this);
        holder.ivFeedBottom.setTag(position);
    }

    //..

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.ivFeedBottom) {
            if (onFeedItemClickListener != null) {
                onFeedItemClickListener.onCommentsClick(v, (Integer) v.getTag());
            }
        }
    }

    public void setOnFeedItemClickListener(OnFeedItemClickListener onFeedItemClickListener) {
        this.onFeedItemClickListener = onFeedItemClickListener;
    }

    //..

    public interface OnFeedItemClickListener {
        public void onCommentsClick(View v, int position);
    }
}

item_comment.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:paddingBottom="8dp"
        android:paddingTop="8dp">

        <ImageView
            android:id="@+id/ivUserAvatar"
            android:layout_width="@dimen/comment_avatar_size"
            android:layout_height="@dimen/comment_avatar_size"
            android:layout_marginLeft="16dp"
            android:layout_marginRight="16dp"
            android:background="@drawable/bg_comment_avatar" />

        <TextView
            android:id="@+id/tvComment"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:text="Lorem ipsum dolor sit amet" />
    </LinearLayout>

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_gravity="bottom"
        android:layout_marginLeft="88dp"
        android:background="#cccccc" />
</FrameLayout>

MainAcitity_view_location.java

public class MainActivity extends ActionBarActivity implements FeedAdapter.OnFeedItemClickListener {
    
    //...

    @Override
    public void onCommentsClick(View v, int position) {
        final Intent intent = new Intent(this, CommentsActivity.class);
        
        //Get location on screen for tapped view
        int[] startingLocation = new int[2];
        v.getLocationOnScreen(startingLocation);
        intent.putExtra(CommentsActivity.ARG_DRAWING_START_LOCATION, startingLocation[1]);
        
        startActivity(intent);
        overridePendingTransition(0, 0);
    }
}

MainActivity.java

//... implements FeedAdapter.OnFeedItemClickListener
public class MainActivity extends ActionBarActivity implements FeedAdapter.OnFeedItemClickListener {

    //...

    private void setupFeed() {
        //...
        feedAdapter.setOnFeedItemClickListener(this);
        //...
    }

    //...
    
    @Override
    public void onCommentsClick(View v, int position) {
    }
}

MainActivity_disable_transition.java

public class MainActivity extends ActionBarActivity implements FeedAdapter.OnFeedItemClickListener {
    //...
    @Override
    public void onCommentsClick(View v, int position) {
        final Intent intent = new Intent(this, CommentsActivity.class);
        startActivity(intent);
        //Disable enter transition for new Acitvity
        overridePendingTransition(0, 0);
    }
}

styles.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- styles.xml-->
<resources>

    <!--...-->

    <style name="AppTheme.CommentsActivity" parent="AppTheme">
        <item name="android:windowBackground">@android:color/transparent</item>
        <item name="android:windowIsTranslucent">true</item>
    </style>
</resources>