android - How to access 'Activity' from a Service class via Intent? -

i new android programming - not have clear understanding of 'context' , 'intent'.
want know there way access activity service class? i.e. let's have 2 classes - 1 extends "activity" , other extends "service" , have created intent in activity class initiate service.

or, how access 'service' class instance 'activity' class - because in such workflow service class not directly instantiated activity-code.

public class mainactivity extends activity {        .               .     @override     protected void oncreate(bundle savedinstancestate) {        super.oncreate(savedinstancestate);        setcontentview(r.layout.activity_main);         startservice(new intent(this, communicationservice.class));        .        .     }   public class communicationservice extends service implements ..... {     .     .     @override     public int onstartcommand(final intent intent, int flags, final int startid) {         super.onstartcommand(intent, flags, startid);         ....     }  } 

you can use bindservice(intent intent, serviceconnection conn, int flags) instead of startservice initiate service. , conn inner class like:

private serviceconnection conn = new serviceconnection() {      @override     public void onserviceconnected(componentname name, ibinder service) {         mmyservice = ((communicationservice.mybinder) service).getservice();     }      @override     public void onservicedisconnected(componentname name) {      } }; 

mmyservice instance of communicationservice.

in communicationservice, override:

public ibinder onbind(intent intent) {     return new mybinder(); } 

and following class in communicationservice:

public class mybinder extends binder {     public communicationservice getservice() {         return communicationservice.this;     } } 

so can use mmyservice access public methods , fields in activity.

in addition, can use callback interface access activity in service.

first write interface like:

public interface onchangelistener {     public void onchanged(int progress); } 

and in service, please add public method:

public void setonchangelistener(onchangelistener onchangelistener) {     this.monchangelistener = onchangelistener; } 

you can use onchanged in service anywhere, , implement in activity:

    public void onserviceconnected(componentname name, ibinder service) {         mmyservice = ((communicationservice.mybinder) service).getservice();         mmyservice.setonchangelistener(new onchangelistener() {             @override             public void onchanged(int progress) {                 // want do, example update progressbar                 // mprogressbar.setprogress(progress);             }         });     } 

ps: bindservice this:

this.bindservice(intent, conn, context.bind_auto_create);

and not forget

protected void ondestroy() {     this.unbindservice(conn);     super.ondestroy(); } 

hope helps.