android - onScroll gets called when I set listView.onScrollListener(this), but without any touch -

when set onscrolllistener listview, calls onscroll. causes crash because things haven't been initialized.

is normal? note: happening without me touching phone.

public class mainactivity1 extends activity implements onclicklistener, onscrolllistener {  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.layout1);      listview lv = (listview)findviewbyid(r.id.listview1);     lv.setonscrolllistener(this);     ... } ... public void onscroll(abslistview view, int firstvisibleitem,         int visibleitemcount, int totalitemcount){     if( firstvisibleitem+visibleitemcount == totalitemcount ){         pullcontactlist();     } } 

it's normal because source code setonscrolllistener in abslistview (the superclass of listview) this:

 public void setonscrolllistener(onscrolllistener l) {         monscrolllistener = l;         invokeonitemscrolllistener();     } 

and invokeonitemscrolllistener this:

/**      * notify our scroll listener (if there one) of change in scroll state */     void invokeonitemscrolllistener() {         if (mfastscroller != null) {             mfastscroller.onscroll(this, mfirstposition, getchildcount(), mitemcount);         }         if (monscrolllistener != null) {             monscrolllistener.onscroll(this, mfirstposition, getchildcount(), mitemcount);         }         onscrollchanged(0, 0, 0, 0); // dummy values, view's implementation not use these.     } 

depending on you're trying do, there number of ways avoid problem.

edit:

since want if user scrolled, suppose like:

    lv.setontouchlistener(new ontouchlistener() {                 @override                 public boolean ontouch(view view, motionevent motionevent) {                     if(view == lv && motionevent.getaction() == motionevent.action_scroll) {                       userscrolled = true;     } return false;                 }             }); 

then..

lv.setonscrolllistener(new abslistview.onscrolllistener() {     @override     public void onscroll(abslistview view, int firstvisibleitem,             int visibleitemcount, int totalitemcount){         if(userscrolled && firstvisibleitem+visibleitemcount == totalitemcount ){             pullcontactlist();         }     }  });