java - Null Pointer Exception -

i'm going nuts trying figure 1 out.when click on activity crashes nullpointerexception.i've tried debugging can't activity in question.i've tried removing database,still crashed.i tried removing listview,still crashed.i tried modifying database,still crashed.

for odd reason when removed button , onclicklistener on "playbutton",i able activity , in activity worked.can me on why button making app crash before activity , not on onclick?

04-05 23:15:15.886: e/androidruntime(11445): fatal exception: main 04-05 23:15:15.886: e/androidruntime(11445): java.lang.runtimeexception: unable start activity componentinfo{com.fullfrontalgames.numberfighter/com.fullfrontalgames.numberfighter.playafriend}: java.lang.nullpointerexception 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activitythread.performlaunchactivity(activitythread.java:2136) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activitythread.handlelaunchactivity(activitythread.java:2174) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activitythread.access$700(activitythread.java:141) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activitythread$h.handlemessage(activitythread.java:1267) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.os.handler.dispatchmessage(handler.java:99) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.os.looper.loop(looper.java:137) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activitythread.main(activitythread.java:5059) 04-05 23:15:15.886: e/androidruntime(11445):    @ java.lang.reflect.method.invokenative(native method) 04-05 23:15:15.886: e/androidruntime(11445):    @ java.lang.reflect.method.invoke(method.java:511) 04-05 23:15:15.886: e/androidruntime(11445):    @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:792) 04-05 23:15:15.886: e/androidruntime(11445):    @ com.android.internal.os.zygoteinit.main(zygoteinit.java:555) 04-05 23:15:15.886: e/androidruntime(11445):    @ dalvik.system.nativestart.main(native method) 04-05 23:15:15.886: e/androidruntime(11445): caused by: java.lang.nullpointerexception 04-05 23:15:15.886: e/androidruntime(11445):    @ com.fullfrontalgames.numberfighter.playafriend.oncreate(playafriend.java:54) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activity.performcreate(activity.java:5058) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1079) 04-05 23:15:15.886: e/androidruntime(11445):    @ android.app.activitythread.performlaunchactivity(activitythread.java:2100) 

activity

package com.fullfrontalgames.numberfighter; import com.fullfrontalgames.numberfighter.dbadapter; import com.fullfrontalgames.numberfighter.r;  import android.app.activity; import android.content.intent; import android.database.cursor;    import android.os.bundle;  import android.support.v4.widget.simplecursoradapter;   import android.view.view; import android.widget.button; import android.widget.listadapter; import android.widget.listview; import android.widget.textview;     public class playafriend extends activity{     dbadapter dbadapter;      @override     protected void oncreate(bundle savedinstancestate) {         // todo auto-generated method stub         super.oncreate(savedinstancestate);         setcontentview(r.layout.playafriend);          final dbadapter db = new dbadapter(this);         dbadapter = db.open();          listview friendlv = (listview) findviewbyid(android.r.id.list);         button playbutton = (button) findviewbyid(r.id.playbutton);         final textview friend = (textview) findviewbyid(r.id.textview_friends);            cursor friendslist = db.getallfriends();          string[] = new string[] {"friends"};   // column/columns here         int[] = new int[] {r.id.textview_friends};          @suppresswarnings("deprecation")         listadapter cursoradapter = new simplecursoradapter(this, r.layout.list_items, friendslist, from, to,0);           friendlv.setadapter(cursoradapter);              playbutton.setonclicklistener(new view.onclicklistener() {                  @override                 public void onclick(view v) {                     // todo auto-generated method stub                      string defender = friend.gettext().tostring();                     db.getfriend(defender);                     startactivity(new intent ("com.fullfrontalgames.numberfighter.fightattacker"));                     db.close();                 }             });          }      } 

playafriend 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:background="@drawable/nfbackground"     android:orientation="vertical" >      <imageview         android:id="@id/titlebar"         android:layout_width="wrap_content"         android:layout_height="66dp"         android:src="@drawable/nftitlebar" />           <listview              android:id="@android:id/list"          android:layout_width="match_parent"          android:layout_height="wrap_content"          android:orientation="vertical" >                </listview>       </linearlayout> 

list_items xml

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" >      <framelayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:padding="5dp"         android:background="@drawable/searchimageview"         android:orientation="vertical" >          <button         android:id="@+id/playbutton"         android:layout_width="60dp"         android:layout_height="60dp"         android:layout_gravity="right"         android:background="@drawable/playbutton" />  <textview      android:id="@+id/textview_friends"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:textcolor="@color/black"     android:textstyle="bold"     android:textsize="40dp"     android:layout_gravity="center" />       </framelayout>    </linearlayout> 

please try code.

 public class test extends activity{         dbadapter dbadapter;         listview friendlv;         button playbutton;         final textview friend;     @override     protected void oncreate(bundle savedinstancestate) {         // todo auto-generated method stub         super.oncreate(savedinstancestate);         setcontentview(r.layout.playafriend);         final dbadapter db = new dbadapter(this);         db.open();         cursor friendslist = db.getallfriends();          if(friendslist.getcount()!=0){              friendlv = (listview) findviewbyid(android.r.id.list);              playbutton = (button) findviewbyid(r.id.playbutton);              friend = (textview) findviewbyid(r.id.textview_friends);              string[] = new string[] {"friends"};   // column/columns here                 int[] = new int[] {r.id.textview_friends};                  @suppresswarnings("deprecation")                 listadapter cursoradapter = new simplecursoradapter(this, r.layout.list_items, friendslist, from, to,0);                   friendlv.setadapter(cursoradapter);                   playbutton.setonclicklistener(new view.onclicklistener() {                          @override                         public void onclick(view v) {                             // todo auto-generated method stub                              string defender = friend.gettext().tostring();                             db.getfriend(defender);                             startactivity(new intent ("com.fullfrontalgames.numberfighter.fightattacker"));                             db.close();                         }                     });           }     }      } 

if getting problem let me know.