java - Eclipse error : button1 cannot be resolved or is not a field -

here mainactivity.java code :

package com.dg.buttontest3; import android.os.bundle; import android.app.activity; import android.util.log; import android.view.menu; import android.view.view; import android.view.view.onclicklistener; import android.widget.button; public class mainactivity extends activity implements onclicklistener{ button button; @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);     button = (button)findviewbyid(r.id.button1);     button.setonclicklistener(this); }  @override public void onclick(view v) {     // todo auto-generated method stub     log.d("dg","button clicked"); } } 

and here activity_main.xml code :

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"  <button     android:id="@+id/button1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignparentleft="true"     android:layout_alignparenttop="true"     android:layout_marginleft="18dp"     android:layout_margintop="18dp"     android:text="button" />     </linearlayout> 

i getting following error while running code on eclipse adt : button1 cannot resolved or not field. don't understand wrong code. please help.

you haven't posted xml code, code seems working properly:

button = (button)findviewbyid(r.id.button1); 

i'd guess in activity_main.xml never create called button1, or don't use @+id/ prefix.

it should like:

<button     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:id="@+id/button1"/> 

just realised else, need change linearlayout opening tag has >.

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> 

that might cause button never recognised.