scroll - Android - Need help determining how far TextView content has been scrolled through -

i trying determine how of textview user has scrolled through, cursor in total content (not portion of content in viewport) of textview , if they've scrolled bottom question textview, doesn't have observablescrollview or other methods i've seen suggested doing scrollview.

this method in code below isn't being called: trackscrolls(). there different way write code user scrolls of textview call method can track action?

package testv.com.versui;  import android.os.bundle; import android.support.v7.app.appcompatactivity; import android.text.method.scrollingmovementmethod; import android.util.log; import android.view.view; import android.view.viewtreeobserver; import android.widget.button; import android.widget.textview;  public class mainactivity extends appcompatactivity {     textview textviewtitle;     textview textviewlong;     button  buttonaccept;     button  buttondecline;     private static final string tag = "myactivity";       @override    protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);         textviewtitle = (textview)findviewbyid(r.id.textviewtitle);          textviewlong = (textview) findviewbyid(r.id.textviewlong);         textviewlong.setmovementmethod(new scrollingmovementmethod());          buttonaccept = (button)findviewbyid(r.id.buttonaccept);         buttondecline = (button)findviewbyid(r.id.buttondecline);          buttonaccept.setonclicklistener(new view.onclicklistener() {             @override             public void onclick(view view) {                  textviewtitle.settext("clicked accept");                  //fire accept hit tos % read              }         });         buttondecline.setonclicklistener(new view.onclicklistener() {             @override             public void onclick(view view) {                  textviewtitle.settext("clicked declined");                  //fire accept hit tos % read              }         });     }     public void trackscrolls(){         if(textviewlong!=null) {              textviewlong.getviewtreeobserver().addonscrollchangedlistener(new viewtreeobserver.onscrollchangedlistener() {                 @override                 public void onscrollchanged() {                     int yvalue = textviewlong.getscrolly();                     log.v(tag, "in onscrollchanged");                 }             });         }     } } 

thanks