EventBus is a publish/subscribe event bus optimized for Android.

so make it simple,just think EventBus as a framework that allow different compoents to communicate,

usually a subscribe register a certain event,then whenever a publisher has post an event,any subscribes who had register this event will be able to receive the notify.

This is an example,Let's say MainActivity is a subscribe who has register to receive RecvEvent event,

And Second Activity is a publicer who will post a RecvEvent when his btn is clicked.Theoretically speaking,MainActivity is able to recevie the event that posted by SecondActivity.


//From above,we know that EventBus contains three objects:Event,Subscribe,Publisher

//EventpublicclassRecvEvent{privatefinalStringinfo;publicRecvEvent(Stringinfo){this.info=info;}publicStringgetInfo(){returninfo;}}//Subscribe:MainActivitypublicclassMainActivityextendsAppCompatActivity{privateTextViewtvShowInfo;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);tvShowInfo=(TextView)findViewById(R.id.tvShowRecv);//registertorecevieShowRecvEventeventEventBus.getDefault().register(this);}@OverrideprotectedvoidonDestroy(){super.onDestroy();//destroyresEventBus.getDefault().unregister(this);}@Subscribe(threadMode=ThreadMode.MAIN)publicvoidonRecvEvent(ShowRecvEventevent){tvShowInfo.setText(event.getInfo());}publicvoidonJump(Viewview){startActivity(newIntent(this,SecondActivity.class));}}//publisher:SecondActivitypublicclassSecondActivityextendsActivity{@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.second_activity);}publicvoidonSend(Viewview){EventBus.getDefault().post(newShowRecvEvent("thisisfromsecondactivity"));}}