java - problems with R - ANDROID -

when create layout called " main.xml ":

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:orientation="vertical"     android:padding="10dip"     android:layout_width="fill_parent"     android:layout_height="wrap_content">     <button         android:id="@+id/button"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/button" />      <spinner         android:id="@+id/spinner"         android:layout_width="fill_parent"         android:layout_height="wrap_content"     /> </linearlayout> 

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when go main create button " button = (button) findviewbyid(r.id.button); " have error , cant find button in r.id , same spinner id dont exist in r.id

help me plz

you're importing wrong version of r. there 2 versions exist: static r class exists in android.r , there yourpackagename.r. if import former none of ids found.