java - How to fetch toggle button value in previouse activity in Android? -

i have create application service run in background system , 2 activities.i have start service in activity1 , in activity2 have put toggle button "yes" , "no". when run application service start in activity1 , when opening activity2 activity1 toggle button status automatically "on" service status using shared preferences when pressed toggle button "off" stopping service got nullpointerexception.i have tried not working .please can 1 me.here code

  public class service_demo extends activity implements onclicklistener {           private static final string tag = "servicesdemo";           button buttonstart, buttonstop;         //  boolean value;            @override           public void oncreate(bundle savedinstancestate)           {             super.oncreate(savedinstancestate);             setcontentview(r.layout.main);             system.out.println("in oncreate(");              startservice(new intent(this, myservice.class));                  buttonstart = (button) findviewbyid(r.id.buttonstart);                 buttonstart.setonclicklistener(this);              boolean value=getintent().getextras().getboolean("togglebtn");             log.e("boolean value","4 toggle button in service demo"+value);            }      public void onclick(view src)            {                       intent i=new intent(this , toggle_activity.class);                     startactivity(i);                 }     }           public class toggle_activity extends activity     {         togglebutton tgbutton;         private boolean isservice=false;         private string strservice;         public final string service_prefs="serviceprefs";         private static final string strmyservice = "zdf";         public static boolean status=false;           public void oncreate(bundle savedinstancestate)         {             super.oncreate(savedinstancestate);             setcontentview(r.layout.toggle);              final sharedpreferences        serviceprefs=this.getsharedpreferences("service_prefs",mode_world_readable);             strservice=serviceprefs.getstring(strmyservice , "myservice");             log.e("",""+strservice);              final boolean mbool = serviceprefs.getboolean("myservice", true);             log.e("boolean value mbool","="+mbool);             boolean b = mbool;             log.e("update pref", b.tostring());             tgbutton = (togglebutton)findviewbyid(r.id.togglebutton);             tgbutton.setchecked(mbool);                 system.out.println("*****tgbutton.setchecked(mbool1);****");             final boolean mbool1 = serviceprefs.getboolean("myservice", false);             log.e("boolean value mbool","="+mbool1);               final boolean c = mbool1;             log.e("update pref", c.tostring());                tgbutton=(togglebutton)findviewbyid(r.id.togglebutton);             tgbutton.setonclicklistener(new onclicklistener()      {                  @override                 public void onclick(view v)      {                     // todo auto-generated method stub                      if(tgbutton.ischecked())                     {                         startservice(new intent(toggle_activity.this , myservice.class));                         system.out.println("service started in togglr button");                       }                     else                      {                             stopservice(new intent(toggle_activity.this,myservice.class));                         intent intent=new intent(toggle_activity.this,service_demo.class);                         status=false;                         intent.putextra("togglebtn",status);                         startactivity(intent);                     }                 }             });           }   }                                                      fatal exception: main                                  java.lang.runtimeexception: unable start activity componentinfo{com.toggle_button/com.toggle_button.service_demo}: java.lang.nullpointerexception                         @ android.app.activitythread.performlaunchactivity(activitythread.java:1647) 05-15 12:44:32.154: e/androidruntime(793):  @ android.app.activitythread.handlelaunchactivity(activitythread.java:1663) 05-15 12:44:32.154: e/androidruntime(793):  @ android.app.activitythread.access$1500(activitythread.java:117) 05-15 12:44:32.154: e/androidruntime(793):  @ android.app.activitythread$h.handlemessage(activitythread.java:931) 05-15 12:44:32.154: e/androidruntime(793):  @ android.os.handler.dispatchmessage(handler.java:99) 05-15 12:44:32.154: e/androidruntime(793):  @ android.os.looper.loop(looper.java:123) 05-15 12:44:32.154: e/androidruntime(793):  @ android.app.activitythread.main(activitythread.java:3683) 05-15 12:44:32.154: e/androidruntime(793):  @ java.lang.reflect.method.invokenative(native method) 05-15 12:44:32.154: e/androidruntime(793):  @ java.lang.reflect.method.invoke(method.java:507) 05-15 12:44:32.154: e/androidruntime(793):  @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:839) 05-15 12:44:32.154: e/androidruntime(793):  @ com.android.internal.os.zygoteinit.main(zygoteinit.java:597) 05-15 12:44:32.154: e/androidruntime(793):  @ dalvik.system.nativestart.main(native method) 05-15 12:44:32.154: e/androidruntime(793): caused by: java.lang.nullpointerexception 05-15 12:44:32.154: e/androidruntime(793):  @ com.toggle_button.service_demo.oncreate(service_demo.java:43) 05-15 12:44:32.154: e/androidruntime(793):  @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1047) 05-15 12:44:32.154: e/androidruntime(793):  @ android.app.activitythread.performlaunchactivity(activitythread.java:1611) 05-15 12:44:32.154: e/androidruntime(793):  ... 11 more 

first activity:

string togvalue = togglebtn.gettext().tostring();  intent = new intent(first.this, sec.class); i.putextra("togvalue", togvalue); startactivity(i); 

second activity:

string togvalue = getintent().getstringextra("togvalue");