RecyclerView scrolls to top position when change the adapter data

Question

I am doing the like and dislike for a post in a RecyclerView, I call the api after changing the view but the problem is that the RecyclerView always scrolls to the top when I notify it with the updates.

this is my adapter code :

 likeAnim.setOnLikeListener(object : OnLikeListener {
            override fun liked(p0: LikeButton?) {
                if (commentList[position]!!.liked) {
                    // 
 likeButton.setBackgroundResource(R.drawable.heart_ico)
                    isLiked = false
                    callback(commentList[position], 2, layoutPosition)
                } else {
                    // likeButton.setBackgroundResource(R.drawable.filled_like_ico)
                    isLiked = true
                    callback(commentList[position], 1, layoutPosition)
                }
            }

            override fun unLiked(p0: LikeButton?) {
                if (commentList[position]!!.liked) {
                    // likeButton.setBackgroundResource(R.drawable.heart_ico)
                    isLiked = false
                    callback(commentList[position], 2, layoutPosition)
                } else {
                    // likeButton.setBackgroundResource(R.drawable.filled_like_ico)
                    isLiked = true
                    callback(commentList[position], 1, layoutPosition)
                }
            }
        })

this is my activity code

        private fun onCommentActionSuccess(list: LikeRequestModel, type: Int, position: Int) {
    when (type) {
        1 -> Log.d("Success", "success: comment like done")
        2 -> Log.d("Success", "success: comment dislike done")
    }
    viewModel.getClassComments(LoginClass.login.user!!.data!!.school_classes_id!![0].id).observe(this@ClassHomeScreenActivity, Observer {
        when {
            it!!.isSuccess() -> onSuccessRefrech(it.data!!.data, position)
        }
    })
}

   private fun onSuccessRefrech(list: MutableList<ClasseCommentModel.Data?>, 
    position: Int) {
    Log.d("Success", "success: comment loaded")
    //initCommentAdapter(list)
    adapter.commentList = list
    // val adapter = ClassCommentsListAdapter(this@ClassHomeScreenActivity, 
      list) { it, type, pos ->
     // likeComment(it!!.id.toString(), type, pos)//Kotlin callback 
     instead of interface in java
    //  }
   // binding.postRV.swapAdapter(adapter, false)
    // adapter.notifyItemChanged(position)
    binding.postRV.scrollToPosition(position)
}

my initAdapter function :

       private fun initCommentAdapter(list: 
        MutableList<ClasseCommentModel.Data?>) {
    adapter = ClassCommentsListAdapter(this@ClassHomeScreenActivity, list) { 
      it, type, position ->
        likeComment(it!!.id.toString(), type, position)//Kotlin callback 
      instead of interface in java
    }
    binding.postRV.setHasFixedSize(true) // 
    binding.postRV.itemAnimator = null // remove recycle view animation
    binding.postRV.layoutManager = 
     LinearLayoutManager(this@ClassHomeScreenActivity, 
      OrientationHelper.VERTICAL, false)
    binding.postRV.adapter = adapter
      }

my callback function :

       private fun likeComment(commentId: String, type: Int, position: Int) {
    when (type) {
        1 -> {
            viewModel.likeComment(commentId).observe(this@ClassHomeScreenActivity, Observer {
                when {
                    it!!.isError() -> onErrorAction(it.error)
                    it.isSuccess() -> onCommentActionSuccess(it.data!!, type, position)
                }
            })
        }
        2 -> {
            viewModel.dislikeComment(commentId).observe(this@ClassHomeScreenActivity, Observer {
                when {
                    it!!.isError() -> onErrorAction(it.error)
                    it.isSuccess() -> onCommentActionSuccess(it.data!!, type, position)
                }
            })
        }
    }
}

private fun onCommentActionSuccess(list: LikeRequestModel, type: Int, 
position: Int) {
    when (type) {
        1 -> Log.d("Success", "success: comment like done")
        2 -> Log.d("Success", "success: comment dislike done")
    }



 viewModel.getClassCommentsSingleEvent
 (LoginClass.login.user!!.data!!.school_clas 
  ses_id!![0].id).observe(this@ClassHomeScreenActivity, Observer {
        when {
            it!!.isSuccess() -> onSuccessRefrech(it.data!!.data, position)
        }
    })
}

I wanna stay in the scroll position without scrolling to top

i did it but always scroll to top – B.mansouri Sep 04 '18 at 10:23 — B.mansouri, Sep 04 '18 at 10:23
what are u doing in your callback function – Shaon Sep 04 '18 at 11:16 — Shaon, Sep 04 '18 at 11:16
@Shaon i add the code on the top check it please – B.mansouri Sep 04 '18 at 11:24 — B.mansouri, Sep 04 '18 at 11:24

score 2 · Answer 1 · edited Sep 04 '18 at 11:38

2

Some tips:

Don't use multiple objects of adapter. Use only single object and try to update the data. Don't set adapter again after updating data.
After updating list just calling adapter.notifydatasetchanged() will solve your problem.

Hopefully this will solve your problem.

edited Sep 04 '18 at 11:38

jake

520
2
10

answered Sep 04 '18 at 10:21

Muhammad Zahab Ahmad Khan

486
3
13

yeah i use only one adapter – B.mansouri Sep 04 '18 at 10:24

score 0 · Answer 2 · answered Sep 06 '18 at 10:15

Not sure if this solves your problem but I was having the same issue and it was because I was calling setAdapter after notify. So, not calling setAdapter after notify solved the problem.

mAdapter.notifyItemRangeInserted(mAdapter.getItemCount(), list.size() - 1);

recyclerView.setAdapter(); // remove this line. //Do this only when you're setting the data for the first time or when adapter is null.

RecyclerView scrolls to top position when change the adapter data

2 Answers2

Linked