How to determine when a user scrolls the top of an element in a RecyclerView

Question

I tried to write the following code

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
  super.onScrolled(recyclerView, dx, dy);
  if(dy > 0){
    //scrolling up
  } else {
    //scrolling down
    int pastVisibleItems = linearLayoutManager.findFirstVisibleItemPosition();
    if (pastVisibleItems  == 0) {
      Toast.makeText(getContext(),"Top most item",Toast.LENGTH_SHORT).show();
    }
  }
}

but that will not work. I also tried using android SwipeRefreshLayout to do this because it does what I want, which is able to detect when the user views the topmost item. I decided not to use it because I cannot prevent the loading indicator from appearing (I do not want the loading indicator to come out at all).

So basically what I want to do:

• check user scroll
• Is this already the topmost item?
• if yes, do something; if not, then nothing

Any idea how to do this?

Thank.

Answer 1

.

private boolean isUserScrolling = false;
private boolean isListGoingUp = true;

RecyclerView OnScrollListener

@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
    super.onScrollStateChanged(recyclerView, newState);
    //detect is the topmost item visible and is user scrolling? if true then only execute
    if(newState ==  RecyclerView.SCROLL_STATE_DRAGGING){
        isUserScrolling = true;
        if(isListGoingUp){
            //my recycler view is actually inverted so I have to write this condition instead
            if(linearLayoutManager.findLastCompletelyVisibleItemPosition() + 1 == list.size()){
                Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        if(isListGoingUp) {
                            if (linearLayoutManager.findLastCompletelyVisibleItemPosition() + 1 == list.size()) {
                                Toast.makeText(getContext(),"exeute something", Toast.LENGTH_SHORT).show();
                            }
                        }
                    }
                },50);
                //waiting for 50ms because when scrolling down from top, the variable isListGoingUp is still true until the onScrolled method is executed
            }
        }
    }
}

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    super.onScrolled(recyclerView, dx, dy);
    if(isUserScrolling){
        if(dy > 0){
            //means user finger is moving up but the list is going down
            isListGoingUp = false;
        }
        else{
            //means user finger is moving down but the list is going up
            isListGoingUp = true;
        }
    }
}

Answer 2

:

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
  super.onScrolled(recyclerView, dx, dy);

  int pastVisibleItems = linearLayoutManager.findFirstCompletelyVisibleItemPosition();
  if (pastVisibleItems  == 0) {
    Toast.makeText(getContext(),"Top most item",Toast.LENGTH_SHORT).show();                
  }
}

, - , .