android - bindService() reported errors with NullPointerException -

i trying bind service , activity can setup service time , present on activty. program reported errors as:

public void starttimeservice(view v){     startservice(intent);     log.d(tag,"--starttimeservice--");       bindservice(intent, con, service.bind_auto_create);         log.d(tag,"post--starttimeservice")**;         tv.settext("current time is：/n"+mbinder.getservice().gettime()); 

running program can log as: --starttimeservice-- , post--starttimeservice，but report error still:

07-13 08:23:19.832: e/androidruntime(3217): caused by: java.lang.nullpointerexception: attempt invoke virtual method 'com.himanmin.xu.servicedemo.timeservice com.himanmin.xu.servicedemo.timeservice$mybinder.getservice()' on null object reference

the code timeservice.java following:

 public class timeservice extends service {     private final string tag = "timeservice";     private int state;     private int count;     private boolean quit;      public class mybinder extends binder{         public timeservice getservice(){             log.d(tag,"--getservice()");             return timeservice.this;         }     }      private mybinder mbinder = new mybinder();      public int getstate(){         //get state of service         log.d(tag,"--getstate()");         return state;     }      public string gettime(){         log.d(tag,"--gettime()");         simpledateformat dateformat24 = new simpledateformat("yyyy-mm-dd hh:mm:ss");           //12 format          //simpledateformat dateformat12 = new simpledateformat("yyyy-mm-dd hh:mm:ss");           return dateformat24.format(calendar.getinstance().gettime());     }      public int getcount(){         log.d(tag,"--getcount()");         return count;     }     @override     public ibinder onbind(intent intent) {         // todo auto-generated method stub         log.d(tag,"--onbind");         system.out.println("service binded");         return mbinder;     }      @override     public void oncreate(){         super.oncreate();         log.d(tag,"--oncreate");**         system.out.println("service time created");         count = (int) system.currenttimemillis();     }     @override     public boolean onunbind(intent intent){         log.d(tag,"--onunbind");         system.out.println("serveice unbinded");         count = (int) (system.currenttimemillis() - count);         return true;     }      @override     public void ondestroy(){         super.ondestroy();         log.d(tag,"--ondestroy");         this.quit = true;         system.out.println("service time destoryed");         count = (int) (system.currenttimemillis() - count);     } } 

after running bindservice（）,method oncreate（） of timeservice class invoked，it should logcat --oncreate，but there no such log, taht means bindservice(intent, con, service.bind_auto_create) has not ran. can not figure out reason that. intent , mainfest.xml follows:

private final string serviceaction = "com.himanmin.xu.servicedemo.time_service";  intent = new intent(); intent.setaction(serviceaction);  <service android:name = "com.himanmin.xu.servicedemo.timeservice">             <intent-filter>                 <action android:name="com.himanmin.xu.servicedemo.time_service"/>             </intent-filter>         </service> 

can guys me figure problem out?

the problem seems service takes time start. when call:

bindservice(intent, con, service.bind_auto_create); 

the method fire intent , return immediately. android system start service @ soonest available time. therefore when call:

tv.settext("current time is：/n"+mbinder.getservice().gettime()); 

your service hasn't started yet, why null pointer exception.

to solve this, must implement service connection described in android bound services doc page (modified fit case):

/** defines callbacks service binding, passed bindservice() */ private serviceconnection mconnection = new serviceconnection() {      @override     public void onserviceconnected(componentname classname,             ibinder service) {         // we've bound localservice, cast ibinder , localservice instance         mbinder = (mybinder) service;         tv.settext("current time is：/n"+mbinder.getservice().gettime());         mbound = true;     }      @override     public void onservicedisconnected(componentname arg0) {         mbound = false;     } }; 

only after onserviceconnected method called , mbound set true can use mbinder object.