Detect Scroll Up Scroll down in ListView

Question

I have the following requirement    At first  data for page no  2 is fetched from the server  amp  the items are populated in a ListView    Considering that both the prev page  amp  next page are available in a scenario  the following code has been added    if prevPageNo  gt  0       mListViewActual setOnScrollListener this        if nextPageNo  gt  0       mListViewActual setOnScrollListener this        What conditions should I put to detect scroll up  amp  scroll down on the following methods    void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount  void onScrollStateChanged AbsListView view  int scrollState    After the action  scroll up  amp  scroll down is detected   accordingly a service will be called with either the prev page no or next page no   to fetch the items to be populated in the Listview   Any inputs will be helpful   Gone through the following links but its not returning the correct scroll up   scroll down action   link 1 link 2

User · Answer

Trick about detect scroll up or down in listview  you just call this function on onScroll function in OnScrollListener of ListView   private int oldFirstVisibleItem   -1      private protected int oldTop   -1         you can change this value  pixel      private static final int MAX SCROLL DIFF   5       private void calculateListScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount            if  firstVisibleItem    oldFirstVisibleItem                int top   view getChildAt 0  getTop                   range between new top and old top must greater than MAX SCROLL DIFF             if  top  gt  oldTop  amp  amp  Math abs top - oldTop   gt  MAX SCROLL DIFF                       scroll up               else if  top  lt  oldTop  amp  amp  Math abs top - oldTop   gt  MAX SCROLL DIFF                       scroll down                           oldTop   top            else               View child   view getChildAt 0               if  child    null                    oldFirstVisibleItem   firstVisibleItem                  oldTop   child getTop

User · Answer

For some reason the Android doc doesnt cover this  and the method used isnt even in the docs    took me a while to find it   To detect if your scroll is at the top you would use this   public boolean checkAtTop          if listView getChildCount      0  return true      return listView getChildAt 0  getTop      0      This will check if your scroller is at the top  Now  in order to do it for the bottom  you would have to pass it the number of children that you have  and check against that number  You might have to figure out how many are on the screen at one time  and subtract that from your number of children  I ve never had to do that  Hope this helps

User · Answer

Here s what I would try first   1  Create an interface  let s call it OnScrollTopOrBottomListener  with these methods   void onScrollTop     void onScrollBottom     2  In your list s adapter  add a member instance  typed as the interface you created and supply a setter and getter   3  In the getView   implementation of your adapter  check if the position parameter is either 0 or getCount   - 1   Also check that your OnScrollTopOrBottomListener instance is not null   4  If the position is 0  call onScrollTopOrBottomListener onScrollTop    If position is getCount   - 1  call onScrollTopOrBottomListener onScrollBottom     5  In your OnScrollTopOrBottomListener implementation  call the appropriate methods to get the desired data   Hope that helps in some way   -Brandon

User · Answer

Just set scroll listener to your listview   If you have a header or footer you should check the visible count too  If it increases it means you are scrolling down   Reverse it if there is a footer instead of header   If you don t have any header or footer in your listview you can remove the lines which cheks the visible item count   listView setOnScrollListener new AbsListView OnScrollListener             public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount                if  mLastFirstVisibleItem  gt  firstVisibleItem                    Log e getClass   toString     scrolling up                  else if  mLastFirstVisibleItem  lt  firstVisibleItem                    Log e getClass   toString     scrolling down                  else if  mLastVisibleItemCount  lt  visibleItemCount                    Log e getClass   toString     scrolling down                  else if  mLastVisibleItemCount  gt  visibleItemCount                    Log e getClass   toString     scrolling up                              mLastFirstVisibleItem   firstVisibleItem              mLastVisibleItemCount   visibleItemCount                     public void onScrollStateChanged AbsListView listView  int scrollState                        and have this variables  int mLastFirstVisibleItem  int mLastVisibleItemCount

User · Answer

To also detect scrolling with larger elements  I prefere an onTouch Listener   listview setOnTouchListener new View OnTouchListener              int scrollEventListSize   5           float lastY             Used to correct for occasions when user scrolls down  up  but the onTouchListener detects it incorrectly  We will store detected up- down-scrolls with -1 1 in this list and evaluate later which occured more often         List lt Integer gt  downScrolledEventsHappened            Override         public boolean onTouch View v  MotionEvent event                 float diff   0              if event getAction      event ACTION DOWN                   lastY   event getY                    downScrolledEventsHappened   new LinkedList lt Integer gt                               else if event getAction      event ACTION MOVE                   diff   event getY   - lastY                  lastY   event getY                     if diff gt 0                      downScrolledEventsHappened add 1                   else                      downScrolledEventsHappened add -1                     List needs to be filled with some events  will happen very quickly                 if downScrolledEventsHappened size      scrollEventListSize 1                       downScrolledEventsHappened remove 0                       int res 0                      for int i 0  i lt downScrolledEventsHappened size    i                             res  downScrolledEventsHappened get i                                              if  res  gt  0                           Log i  INFO    Scrolled up                        else                          Log i  INFO    Scrolled down                                                return false     don t interrupt the event-chain

User · Answer

ListView listView   getListView                listView setOnScrollListener new OnScrollListener                       Override                 public void onScrollStateChanged AbsListView view  int scrollState                         view setOnTouchListener new OnTouchListener                             private float mInitialX                          private float mInitialY                            Override                         public boolean onTouch View v  MotionEvent event                                switch  event getAction                                      case MotionEvent ACTION DOWN                                      mInitialX   event getX                                        mInitialY   event getY                                        return true                                  case MotionEvent ACTION MOVE                                      final float x   event getX                                        final float y   event getY                                        final float yDiff   y - mInitialY                                      if  yDiff  gt  0 0                                            Log d tag   SCROLL DOWN                                            scrollDown   true                                          break                                         else if  yDiff  lt  0 0                                            Log d tag   SCROLL up                                            scrollDown   true                                          break                                                                             break                                                            return false

User · Answer

I ve used this much simpler solution    setOnScrollListener  new OnScrollListener           private int mInitialScroll   0        Override     public void onScroll AbsListView view  int firstVisibleItem              int visibleItemCount  int totalItemCount                 int scrolledOffset   computeVerticalScrollOffset             boolean scrollUp   scrolledOffset  gt  mInitialScroll          mInitialScroll   scrolledOffset               Override     public void onScrollStateChanged AbsListView view  int scrollState

User · Answer

try using the setOnScrollListener and implement the onScrollStateChanged with scrollState  setOnScrollListener new OnScrollListener        public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount             TODO Auto-generated method stub           public void onScrollStateChanged AbsListView view  int scrollState             TODO Auto-generated method stub       final ListView lw   getListView            if scrollState    0         Log i  a    scrolling stopped                 if  view getId      lw getId              final int currentFirstVisibleItem   lw getFirstVisiblePosition             if  currentFirstVisibleItem  gt  mLastFirstVisibleItem                mIsScrollingUp   false              Log i  a    scrolling down                 else if  currentFirstVisibleItem  lt  mLastFirstVisibleItem                mIsScrollingUp   true              Log i  a    scrolling up                          mLastFirstVisibleItem   currentFirstVisibleItem

User · Answer

Store the firstVisibleItem and on the next onScroll check if the new firstVisibleItem is smaller or greater than the previous one   Example pseudocode  not tested    int lastVisibleItem   0  boolean isScrollingDown   false   void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount        if  firstVisibleItem  gt  lastVisibleItem            isScrollingDown   true            else           isScrollingDown   false            lastVisibleItem   firstVisibleItem

User · Answer

I have encountered problems using some example where the cell size of ListView is great  So I have found a solution to my problem which detects the slightest movement of your finger   I ve simplified to the minimum possible and is as follows   private int oldScrolly     Override public void onScrollStateChanged AbsListView view  int scrollState         Override public void onScroll AbsListView view  int firstVisibleItem  int    visibleItemCount  int totalItemCount                 View view   absListView getChildAt 0               int scrolly    view    null    0   -view getTop     absListView getFirstVisiblePosition     view getHeight                int margin   10               Log e TAG   Scroll y      scrolly     - Item      firstVisibleItem                 if  scrolly  gt  oldScrolly   margin                    Log d TAG   SCROLL UP                    oldScrolly   scrolly                else if  scrolly  lt  oldScrolly - margin                    Log d TAG   SCROLL DOWN                    oldScrolly   scrolly                                    PD  I use the MARGIN to not detect the scroll until you meet that margin   This avoids problems when I show or hide views and avoid blinking of them

User · Answer

My solution works perfectly giving the exact value for each scroll direction  distanceFromFirstCellToTop contains the exact distance from the first cell to the top of the parent View  I save this value in previousDistanceFromFirstCellToTop and as I scroll I compare it with the new value  If it s lower then I scrolled up  else  I scrolled down   private int previousDistanceFromFirstCellToTop   listview setOnScrollListener new OnScrollListener           Override     public void onScrollStateChanged AbsListView view  int scrollState                 Override     public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount            View firstCell   listview getChildAt 0           int distanceFromFirstCellToTop   listview getFirstVisiblePosition     firstCell getHeight   - firstCell getTop             if distanceFromFirstCellToTop  lt  previousDistanceFromFirstCellToTop                         Scroll Up                   else if distanceFromFirstCellToTop   gt  previousDistanceFromFirstCellToTop                         Scroll Down                   previousDistanceFromFirstCellToTop   distanceFromFirstCellToTop              For Xamarin developers  the solution is the following   Note  don t forget to run on UI thread  listView Scroll     o  e    gt        View firstCell   listView GetChildAt 0       int distanceFromFirstCellToTop   listView FirstVisiblePosition   firstCell Height - firstCell Top       if  distanceFromFirstCellToTop  lt  previousDistanceFromFirstCellToTop                  Scroll Up           else if  distanceFromFirstCellToTop  gt  previousDistanceFromFirstCellToTop                  Scroll Down           previousDistanceFromFirstCellToTop   distanceFromFirstCellToTop

User · Answer

Here is a working modified version from some of the above-indicated solutions   Add another class ListView   package com example view   import android content Context  import android util AttributeSet  import android view View  import android widget AbsListView   public class ListView extends android widget ListView        private OnScrollListener onScrollListener      private OnDetectScrollListener onDetectScrollListener       public ListView Context context            super context           onCreate context  null  null              public ListView Context context  AttributeSet attrs            super context  attrs           onCreate context  attrs  null              public ListView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           onCreate context  attrs  defStyle               SuppressWarnings  UnusedParameters       private void onCreate Context context  AttributeSet attrs  Integer defStyle            setListeners               private void setListeners             super setOnScrollListener new OnScrollListener                  private int oldTop              private int oldFirstVisibleItem                Override             public void onScrollStateChanged AbsListView view  int scrollState                    if  onScrollListener    null                        onScrollListener onScrollStateChanged view  scrollState                                                 Override             public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount                    if  onScrollListener    null                        onScrollListener onScroll view  firstVisibleItem  visibleItemCount  totalItemCount                                      if  onDetectScrollListener    null                        onDetectedListScroll view  firstVisibleItem                                                private void onDetectedListScroll AbsListView absListView  int firstVisibleItem                    View view   absListView getChildAt 0                   int top    view    null    0   view getTop                     if  firstVisibleItem    oldFirstVisibleItem                        if  top  gt  oldTop                            onDetectScrollListener onUpScrolling                          else if  top  lt  oldTop                            onDetectScrollListener onDownScrolling                                            else                       if  firstVisibleItem  lt  oldFirstVisibleItem                            onDetectScrollListener onUpScrolling                          else                           onDetectScrollListener onDownScrolling                                                             oldTop   top                  oldFirstVisibleItem   firstVisibleItem                                        Override     public void setOnScrollListener OnScrollListener onScrollListener            this onScrollListener   onScrollListener             public void setOnDetectScrollListener OnDetectScrollListener onDetectScrollListener            this onDetectScrollListener   onDetectScrollListener            And an interface   public interface OnDetectScrollListener        void onUpScrolling         void onDownScrolling        And finally how to use   com example view ListView listView    com example view ListView  findViewById R id list   listView setOnDetectScrollListener new OnDetectScrollListener          Override     public void onUpScrolling                do something                Override     public void onDownScrolling                do something                In your XML layout    lt com example view ListView     android id    id list      android layout width  match parent      android layout height  match parent   gt    This is my first topic  do not judge me harshly

User · Answer

this is a simple implementation   lv setOnScrollListener new OnScrollListener             private int mLastFirstVisibleItem            Override         public void onScrollStateChanged AbsListView view  int scrollState                         Override         public void onScroll AbsListView view  int firstVisibleItem                  int visibleItemCount  int totalItemCount                 if mLastFirstVisibleItem lt firstVisibleItem                                Log i  SCROLLING DOWN   TRUE                              if mLastFirstVisibleItem gt firstVisibleItem                                Log i  SCROLLING UP   TRUE                              mLastFirstVisibleItem firstVisibleItem                       and if you need more precision  you can use this custom ListView class   import android content Context  import android util AttributeSet  import android view View  import android widget AbsListView  import android widget ListView          Created by root on 26 05 15      public class ScrollInterfacedListView extends ListView         private OnScrollListener onScrollListener      private OnDetectScrollListener onDetectScrollListener       public ScrollInterfacedListView Context context            super context           onCreate context  null  null              public ScrollInterfacedListView Context context  AttributeSet attrs            super context  attrs           onCreate context  attrs  null              public ScrollInterfacedListView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           onCreate context  attrs  defStyle               SuppressWarnings  UnusedParameters       private void onCreate Context context  AttributeSet attrs  Integer defStyle            setListeners               private void setListeners             super setOnScrollListener new OnScrollListener                  private int oldTop              private int oldFirstVisibleItem                Override             public void onScrollStateChanged AbsListView view  int scrollState                    if  onScrollListener    null                        onScrollListener onScrollStateChanged view  scrollState                                                 Override             public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount                    if  onScrollListener    null                        onScrollListener onScroll view  firstVisibleItem  visibleItemCount  totalItemCount                                      if  onDetectScrollListener    null                        onDetectedListScroll view  firstVisibleItem                                                private void onDetectedListScroll AbsListView absListView  int firstVisibleItem                    View view   absListView getChildAt 0                   int top    view    null    0   view getTop                     if  firstVisibleItem    oldFirstVisibleItem                        if  top  gt  oldTop                            onDetectScrollListener onUpScrolling                          else if  top  lt  oldTop                            onDetectScrollListener onDownScrolling                                            else                       if  firstVisibleItem  lt  oldFirstVisibleItem                            onDetectScrollListener onUpScrolling                          else                           onDetectScrollListener onDownScrolling                                                             oldTop   top                  oldFirstVisibleItem   firstVisibleItem                                        Override     public void setOnScrollListener OnScrollListener onScrollListener            this onScrollListener   onScrollListener             public void setOnDetectScrollListener OnDetectScrollListener onDetectScrollListener            this onDetectScrollListener   onDetectScrollListener              public interface OnDetectScrollListener            void onUpScrolling             void onDownScrolling               an example for use   don t forget to add it as an Xml Tag in your layout xml   scrollInterfacedListView setOnDetectScrollListener new ScrollInterfacedListView OnDetectScrollListener                  Override             public void onUpScrolling                      Do your thing                             Override             public void onDownScrolling                     Do your thing

User · Answer

Simple way to load more items on scroll up down event in android GridView      grid setOnScrollListener new AbsListView OnScrollListener                     private int mLastFirstVisibleItem                   Override                 public void onScrollStateChanged AbsListView view  int scrollState                           TODO Auto-generated method stub                     Log d  state  String valueOf scrollState                          if scrollState    0                          Log i  a    scrolling stopped                             if  view getId      grid getId                               final int currentFirstVisibleItem   grid getLastVisiblePosition                            mLastFirstVisibleItem   grid getFirstVisiblePosition                             if  currentFirstVisibleItem  gt  mLastFirstVisibleItem                                mIsScrollingUp   false                              if  next contains  null                                   Call api to get products from server                                                               Log i  a    scrolling down                                 else if  currentFirstVisibleItem  lt  mLastFirstVisibleItem                                mIsScrollingUp   true                              Log i  a    scrolling up                                                          mLastFirstVisibleItem   currentFirstVisibleItem                                                        Override             public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount                    Log d  on scroll

User · Answer

Those methods cannot be used to detect scrolling directions directly  There are many ways of getting the direction  A simple code untested  for one such method is explained below      public class ScrollTrackingListView extends ListView        private boolean readyForMeasurement   false      private Boolean isScrollable   null      private float prevDistanceToEnd   -1 0      private ScrollDirectionListener listener   null       public ScrollTrackingListView Context context            super context           init               public ScrollTrackingListView Context context  AttributeSet attrs            super context  attrs           init               public ScrollTrackingListView Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle           init               private void init             ViewTreeObserver observer   getViewTreeObserver            observer addOnGlobalLayoutListener globalLayoutListener           setOnScrollListener scrollListener              private ViewTreeObserver OnGlobalLayoutListener globalLayoutListener               new ViewTreeObserver OnGlobalLayoutListener               Override         public void onGlobalLayout                 readyForMeasurement   true              calculateDistanceToEnd                           public void registerScrollDirectionListener ScrollDirectionListener listener            scrollDirectionListener   listener             public void unregisterScrollDirectionListener             scrollDirectionListener   null             private OnScrollListener scrollListener               new OnScrollListener               Override         public void onScrollStateChanged AbsListView absListView  int i                calculateDistanceToEnd                        Override         public void onScroll AbsListView absListView  int i  int i1  int i2                   Do nothing                        private void calculateDistanceToEnd              if  readyForMeasurement                    I m using the height of the layout  horizontal scrollbar and                content along with scroll down offset                 computeVerticalScrollExtent is used to compute the length of the thumb within the scrollbar s track                 The length of the thumb is a function of the view height and the content length              int verticalScrollExtent   computeVerticalScrollExtent                int verticalScrollOffset   computeVerticalScrollOffset                int verticalScrollRange   computeVerticalScrollRange                int horizontalScrollBarHeight   getHorizontalScrollbarHeight                                    1  Let  R  represent the range of the vertical scrollbar  This corresponds to the length of the content                in the view                 2  Let  E  represent the extent of the vertical scrollbar  The extent is a constant value and is                 probably  equal to a value proportional to the height of the view                 3  Offset  o  represents the current position in the range that is visible to the user  It can take                values from  0 to E                                 Now the DistanceToEnd is calculated using these three values as follows                                 DistanceToEnd    R - o    E                               DistanceToEnd will hold the value in NumberOfScreenToEnd units                                              float distanceToEnd                         float  verticalScrollRange - verticalScrollOffset     float  verticalScrollExtent                 if prevDistanceToEnd    -1                     prevDistanceToEnd   distanceToEnd                else                    if listener    null                         if distanceToEnd   prevDistanceToEnd                               User is scrolling up                          listener onScrollingUp                           else                              User is scrolling up                          listener onScrollingDown                                                              prevDistanceToEnd   distanceToEnd                             if isScrollable    null                       Check if the view height is less than a screen  i e   no scrolling is enabled                  if  horizontalScrollBarHeight   verticalScrollExtent     verticalScrollRange                        isScrollable   Boolean FALSE                    else                       isScrollable   Boolean TRUE                                                         public interface ScrollDirectionListener            public void onScrollingUp             public void onScrollingDown                The idea is to calculate the distanceToEnd  If distanceToEnd increases  the user is scrolling up and if it decreases  the user is scrolling down  That will also give you the exact distance to the end of the list   If you are just trying to know whether the user is scrolling up or down you can override the onInterceptTouchEvent to detect the scrolling direction like below          Override     public boolean onInterceptTouchEvent MotionEvent event            switch  event getAction                  case MotionEvent ACTION DOWN                  mInitialX   event getX                    mInitialY   event getY                    return true              case MotionEvent ACTION MOVE                  final float x   event getX                    final float y   event getY                    final float yDiff   y - mInitialY     yDiff less than 0 0 implies scrolling down while yDiff greater than 0 0 implies scrolling up  If I try to add the less than or greater than symbols  the preview refuses to display it                  if yDiff less than 0 0  listener onScrollingDown                    else if yDiff greater than 0 0  listener onScrollingUp                    break                    return super onInterceptTouchEvent event

User · Answer

With all the method posted  there are problems recognizing when the user is scrolling up from the first element or down from the last   Here is another approach to detect scroll up down           listView setOnTouchListener new View OnTouchListener                 float height               Override             public boolean onTouch View v  MotionEvent event                    int action   event getAction                    float height   event getY                    if action    MotionEvent ACTION DOWN                       this height   height                   else if action    MotionEvent ACTION UP                       if this height  lt  height                           Log v TAG   Scrolled up                         else if this height  gt  height                           Log v TAG   Scrolled down                                                            return false

User · Answer

Simple way to detect scroll up down on android listview   Override public void onScroll AbsListView view  int firstVisibleItem  int visibleItemCount  int totalItemCount     if prevVisibleItem    firstVisibleItem       if prevVisibleItem  lt  firstVisibleItem          ScrollDown     else         ScrollUp    prevVisibleItem   firstVisibleItem      dont forget  yourListView setOnScrollListener yourScrollListener

[android] Detect Scroll Up & Scroll down in ListView

Examples related to android

Examples related to android-listview

Examples related to scrollbar