android - Why does my app crash on calling a Service from a Broadcast Receiver on a Button click? -

i have developed app in service keeps running in background. service started broadcast receiver after every 3 minutes. broadcast receiver initiated button click. problem getting following errors when click button start broadcast receiver. can tell me going wrong?

my broadcast receiver follows:

public class k extends broadcastreceiver{      public static alarmmanager am;        @suppresslint("newapi")        @override      public void onreceive(context context, intent arg1) {     // todo auto-generated method stub     intent broadcast = new intent(context, k.class);     pendingintent pendingintent = pendingintent.getbroadcast(context, 0, broadcast, 0);     alarmmanager alarmmanager = (alarmmanager) context.getsystemservice(context.alarm_service);     alarmmanager.setrepeating(alarmmanager.rtc_wakeup,system.currenttimemillis()+1000, 300000, pendingintent);      intent = new intent(context,ser.class);      context.getapplicationcontext().startservice(i);  } } 

and service follows:

public class ser extends service implements locationlistener {     public location getlocation(string provider) {     if (locationmanager.isproviderenabled(provider)) {         locationmanager.requestlocationupdates(provider,                 min_time_for_update, min_distance_for_update, this);         if (locationmanager != null) {             location = locationmanager.getlastknownlocation(provider);              double latitude = location.getlatitude();             double longitude = location.getlongitude();             string l1=string.valueof(latitude);             string l2=string.valueof(longitude);          }     }      return location; } @override public int onstartcommand(intent intent, int flags, int startid) {     // todo auto-generated method stub      //toast.maketext(this, "service starting", toast.length_short).show();     databasehandler db=new databasehandler(getapplicationcontext());     locationmanager = (locationmanager) getapplicationcontext().getsystemservice(location_service);     getlocation(locationmanager.network_provider);     isgpsenabled = locationmanager.isproviderenabled(locationmanager.gps_provider);      isnetworkenabled = locationmanager     .isproviderenabled(locationmanager.network_provider);     if(isnetworkenabled==true && isgpsenabled==false)     {         getlocation(locationmanager.network_provider);     }     else if(isgpsenabled==true && isnetworkenabled==false)     {         getlocation(locationmanager.gps_provider);     }     else if(isgpsenabled==true && isnetworkenabled==false)     {         getlocation(locationmanager.gps_provider);     }     else if(isgpsenabled==true && isnetworkenabled==true )     {         getlocation(locationmanager.gps_provider);     }        return super.onstartcommand(intent, flags, startid); }       @override    public void onlocationchanged(location location) {     this.location=location;     double latitude =location.getlatitude();     double longitude = location.getlongitude();     databasehandler db=new databasehandler(getapplicationcontext());     string l1=string.valueof(latitude);     string l2=string.valueof(longitude);     val=db.taskid(l1, l2);   } 

and here error log;

 03-21 16:11:37.515: e/androidruntime(22504): fatal exception: main  03-21 16:11:37.515: e/androidruntime(22504): java.lang.runtimeexception: unable start service com.example.ishutup.ser@4105d298 intent { cmp=com.example.ishutup/.ser }: java.lang.nullpointerexception  03-21 16:11:37.515: e/androidruntime(22504):   @ android.app.activitythread.handleserviceargs(activitythread.java:2376)  03-21 16:11:37.515: e/androidruntime(22504):   @ android.app.activitythread.access$1900(activitythread.java:123)  03-21 16:11:37.515: e/androidruntime(22504):   @ android.app.activitythread$h.handlemessage(activitythread.java:1210)  03-21 16:11:37.515: e/androidruntime(22504):   @ android.os.handler.dispatchmessage(handler.java:99)  03-21 16:11:37.515: e/androidruntime(22504):   @ android.os.looper.loop(looper.java:137)  03-21 16:11:37.515: e/androidruntime(22504):   @ android.app.activitythread.main(activitythread.java:4424)  03-21 16:11:37.515: e/androidruntime(22504):   @ java.lang.reflect.method.invokenative(native method)  03-21 16:11:37.515: e/androidruntime(22504):   @ java.lang.reflect.method.invoke(method.java:511)  03-21 16:11:37.515: e/androidruntime(22504):   @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:784)  03-21 16:11:37.515: e/androidruntime(22504):   @ com.android.internal.os.zygoteinit.main(zygoteinit.java:551)  03-21 16:11:37.515: e/androidruntime(22504):   @ dalvik.system.nativestart.main(native method)  03-21 16:11:37.515: e/androidruntime(22504): caused by: java.lang.nullpointerexception  03-21 16:11:37.515: e/androidruntime(22504):   @ com.example.ishutup.ser.getlocation(ser.java:40)  03-21 16:11:37.515: e/androidruntime(22504):   @ com.example.ishutup.ser.onstartcommand(ser.java:61)  03-21 16:11:37.515: e/androidruntime(22504):   @ android.app.activitythread.handleserviceargs(activitythread.java:2359)  03-21 16:11:37.515: e/androidruntime(22504):   ... 10 more 

maybe location null.

from locationmanager.getlastknownlocation documentation: if provider disabled, null returned