android - Time Picker widget - "id cannot be resolved or is not a field" -

i'm getting error following lines:

mtimedisplay = (textview) findviewbyid(r.id.timedisplay); mpicktime = (button) findviewbyid(r.id.picktime); 

although @ stage i'm merely copy-pasting stuff tutorial, feel it.. going wrong guys?

this .java file whole:

package com.example.hellotimepicker;  import java.util.calendar;  import android.app.activity; import android.os.bundle; import android.view.view; import android.widget.button; import android.widget.textview;  public class hellotimepicker extends activity {     /** called when activity first created. */      private textview mtimedisplay;     private button mpicktime;      private int mhour;     private int mminute;      static final int time_dialog_id = 0;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.main);          // capture our view elements         mtimedisplay = (textview) findviewbyid(r.id.timedisplay);         mpicktime = (button) findviewbyid(r.id.picktime);          // add click listener button         mpicktime.setonclicklistener(new view.onclicklistener() {             public void onclick(view v) {                 showdialog(time_dialog_id);             }         });          // current time         final calendar c = calendar.getinstance();         mhour = c.get(calendar.hour_of_day);         mminute = c.get(calendar.minute);          // display current date         updatedisplay();      }   // updates time display in textview     private void updatedisplay() {         mtimedisplay.settext(             new stringbuilder()                     .append(pad(mhour)).append(":")                     .append(pad(mminute)));     }      private static string pad(int c) {         if (c >= 10)             return string.valueof(c);         else             return "0" + string.valueof(c);     } } 

sounds missed copy layout (xml code) tutorial