android - java.lang.NullPointerException while running the app after creating layout-land folder -

i have xml working in portrait mode. created 1 more folder landscape layout-land , added same xml , made changes according landscape mode, when run app getting following error.

03-18 09:30:59.276: e/androidruntime(5753): fatal exception: main     03-18 09:30:59.276: e/androidruntime(5753): java.lang.runtimeexception: unable start activity componentinfo{com.netserv.pungry/com.netserv.pungry.restaurantdetails}: java.lang.nullpointerexception     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activitythread.performlaunchactivity(activitythread.java:2180)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activitythread.handlelaunchactivity(activitythread.java:2230)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activitythread.access$600(activitythread.java:141)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activitythread$h.handlemessage(activitythread.java:1234)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.os.handler.dispatchmessage(handler.java:99)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.os.looper.loop(looper.java:137)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activitythread.main(activitythread.java:5041)     03-18 09:30:59.276: e/androidruntime(5753):     @ java.lang.reflect.method.invokenative(native method)     03-18 09:30:59.276: e/androidruntime(5753):     @ java.lang.reflect.method.invoke(method.java:511)     03-18 09:30:59.276: e/androidruntime(5753):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:793)     03-18 09:30:59.276: e/androidruntime(5753):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:560)     03-18 09:30:59.276: e/androidruntime(5753):     @ dalvik.system.nativestart.main(native method)     03-18 09:30:59.276: e/androidruntime(5753): caused by: java.lang.nullpointerexception     03-18 09:30:59.276: e/androidruntime(5753):     @ com.netserv.pungry.restaurantdetails.oncreate(restaurantdetails.java:44)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activity.performcreate(activity.java:5104)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1080)     03-18 09:30:59.276: e/androidruntime(5753):     @ android.app.activitythread.performlaunchactivity(activitythread.java:2144)     03-18 09:30:59.276: e/androidruntime(5753):     ... 11 more 

here xml.

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:gravity="right"     android:orientation="vertical"     android:weightsum="1.0" >    <linearlayout        android:layout_width="match_parent"       android:layout_height="wrap_content"       android:orientation="horizontal"       android:background="@color/headerbgcolor"       android:weightsum="1.0"        >         <button             android:id="@+id/restaurant_back"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_weight="0.2"             android:text="@string/back" />          <textview             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_gravity="center_vertical"             android:layout_weight="0.6"             android:gravity="center"             android:text="@string/restauran_details" />          <button             android:id="@+id/restaurant_home"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_weight="0.2"             android:text="@string/home" />      </linearlayout>    <relativelayout       android:layout_width="wrap_content"       android:layout_height="wrap_content"       >        <button           android:id="@+id/refresh"           android:layout_width="wrap_content"           android:layout_height="20dp"           android:gravity="left"           android:text="@string/refresh" />   </relativelayout>    <linearlayout        android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:orientation="vertical"       android:weightsum="1">       <textview         android:layout_width="fill_parent"         android:layout_height="30dp"         android:text="@string/restaurant_name"          />       <textview          android:layout_width="fill_parent"          android:layout_height="match_parent"          android:text="@string/restaurant_address" />       </linearlayout>      <scrollview          android:layout_width="fill_parent"          android:layout_height="wrap_content" >      <linearlayout          android:layout_width="match_parent"         android:layout_height="200dp"         android:orientation="vertical"         android:weightsum="1" >      <textview         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/restaurant_rating"         android:layout_weight="0.1"  />       <textview         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/restaurant_timings"          android:layout_weight="0.1"  />       <textview         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/cost_for_two"          android:layout_weight="0.1" />       <textview         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/restaurant_cuisine"          android:layout_weight="0.1" />       <textview         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/restaurant_location"          android:layout_weight="0.1" />       <textview         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="@string/restaurant_city"          android:layout_weight="0.1" />  </linearlayout> </scrollview>       <textview         android:layout_width="fill_parent"         android:layout_height="20dp"         android:text="@string/restaurant_phone"         />  <!--      <relativelayout --> <!--         android:layout_width="fill_parent" --> <!--         android:layout_height="wrap_content" > -->  <!--         <imageview --> <!--             android:id="@+id/imageview1" --> <!--             android:layout_width="fill_parent" --> <!--             android:layout_height="wrap_content" --> <!--             android:layout_alignparentbottom="true" --> <!--             android:background="#808000" --> <!--             android:src="@drawable/btn_bg_cuisine" /> --> <!--     </relativelayout> -->   </linearlayout> 

here restaurantdetails class

protected void oncreate(bundle savedinstancestate) {         // todo auto-generated method stub         super.oncreate(savedinstancestate);         setcontentview(r.layout.restaurantdetails);         btnback = (button) findviewbyid(r.id.back);         btnhome = (button) findviewbyid(r.id.restaurant_home);         btnrefresh = (button) findviewbyid(r.id.refresh);         btnrefresh.setvisibility(view.gone);         restaurant_name = (textview) findviewbyid(r.id.restaurant_name);         restaurant_add = (textview) findviewbyid(r.id.restaurant_add);         restaurant_costfortwo = (textview) findviewbyid(r.id.restaurant_cstfortwo);         restaurant_rating = (textview) findviewbyid(r.id.restaurant_rating);         restaurant_timings = (textview) findviewbyid(r.id.restaurant_timings);         restaurant_phone = (textview) findviewbyid(r.id.restaurant_phone);         restaurant_phone.setautolinkmask(linkify.phone_numbers);         restaurant_phone.setlinksclickable(true);          restaurant_locationname = (textview) findviewbyid(r.id.restaurant_location);         restaurant_cityname = (textview) findviewbyid(r.id.restaurant_city);         restaurant_cuisinename = (textview) findviewbyid(r.id.restaurant_cuisine);         imgfooter = (imageview) findviewbyid(r.id.footerimage);          btnhome.setonclicklistener(new view.onclicklistener() {             public void onclick(view v) {                 startactivity(new intent(restaurantdetails.this, home.class));             }         });          restaurant_name.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).restaurant_name);         restaurant_add.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).address);         restaurant_costfortwo.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).costoftwo);         restaurant_rating.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).rating);         restaurant_timings.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).timings);         restaurant_phone.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).phone);         restaurant_locationname.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).location_name);         restaurant_cityname.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).city_name);         restaurant_cuisinename.settext(globvariables.restaurant_response                 .get(globvariables.restaurantname).cuisine_name); 

can know what's mistake doing?.. thanks:)

error in btnback = (button) findviewbyid(r.id.back);.

there no button has id back in layout xml.

i think want use restaurant_back

btnback = (button) findviewbyid(r.id.restaurant_back);.

also textview should have id in xml layout.

restaurant_name = (textview) findviewbyid(r.id.restaurant_name);         restaurant_add = (textview) findviewbyid(r.id.restaurant_add);         restaurant_costfortwo = (textview) findviewbyid(r.id.restaurant_cstfortwo);         restaurant_rating = (textview) findviewbyid(r.id.restaurant_rating);         restaurant_timings = (textview) findviewbyid(r.id.restaurant_timings);         restaurant_phone = (textview) findviewbyid(r.id.restaurant_phone);         restaurant_locationname = (textview) findviewbyid(r.id.restaurant_location);         restaurant_cityname = (textview) findviewbyid(r.id.restaurant_city);         restaurant_cuisinename = (textview) findviewbyid(r.id.restaurant_cuisine);      , image view   imgfooter = (imageview) findviewbyid(r.id.footerimage); 

add in xml layout android:id="@+id/...."

<....              android:id="@+id/...."             .             .             .             />