android - Error inflating class button -

i started learning computer science , android development. i've been going through helloworld demos try , learn.

so going wild, tried rewrite program has 1 button 2 buttons using onclicklistener. while don't have compiling errors, program force closing on me:

01-05 11:20:33.968: e/androidruntime(3257): java.lang.runtimeexception: unable start activity componentinfo{com.example.multbuttontest/com.example.multbuttontest.multibuttonactivity}: android.view.inflateexception: binary xml file line #16: error inflating class button

my xml file looks (sorry suck @ formatting):

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:paddingbottom="@dimen/activity_vertical_margin"     android:paddingleft="@dimen/activity_horizontal_margin"     android:paddingright="@dimen/activity_horizontal_margin"     android:paddingtop="@dimen/activity_vertical_margin"     tools:context=".multibuttonactivity">  <textview     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="@string/hello_world" />  <button      android:id="@+id/button1"     android:layout_width="wrap_content"     android:layout_height="wrap_content" />  <button     android:id="@+id/button2"     android:layout_width="wrap_content"     android:layout_height="wrap_content" /> 

and code:

package com.example.multbuttontest;  import android.os.bundle; import android.app.activity; import android.view.view; import android.widget.button;  public class multibuttonactivity extends activity implements view.onclicklistener{  button button1, button2; int touchcount1, touchcount2;  @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_multi_button);      button1 = (button) findviewbyid(r.id.button1);     button1.settext( "touch button 1!");     button1.setonclicklistener(this);      button2 = (button) findviewbyid(r.id.button2);     button2.settext( "touch button 2!");     button2.setonclicklistener(this); }  public void onclick(view v){     switch(v.getid()){         case r.id.button1:             touchcount1++;             button1.settext("touched b1 " + touchcount1 + " times(s)");             break;         case r.id.button2:             touchcount2++;             button2.settext("touched b2 " + touchcount2 + " times(s)");             break;     } } } 

this strictly learning purposes, , code suck. appreciated.

here code might out.

mainactivity:

public class mainactivity extends activity  {     private textview txt1;     private button btncount,btnclear;      private int num1 = 1;   @override protected void oncreate(bundle savedinstancestate)  {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      txt1 = (textview) findviewbyid(r.id.txt1);      btncount = (button) findviewbyid(r.id.button1);     btnclear = (button) findviewbyid(r.id.button2);   }  public void sendmessage(view view)  {      txt1.settext("you have clicked"+ (num1) + "times");      num1++;  }  public void clear(view view) {     num1 = 1;     txt1.settext("you have clicked"+ (num1) + "times"); }     } 

activity_main.xml:

 <button     android:id="@+id/button1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="@string/button_send"      android:onclick="sendmessage" />  <button     android:id="@+id/button2"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="@string/button_clear"      android:onclick="clear" />  <textview             android:id="@+id/txt1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"      android:text="@+string/pushed" /> 

output: