java - Method's parameters -

i've started learning android development + beginner @ this.

i don't how/where, in case below, parameter of method in instantiated.

public class mainactivity extends activity { @override protected void oncreate(**bundle savedinstancestate**) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      radiogroup group1 = (radiogroup) findviewbyid(r.id.orientation);     group1.setoncheckedchangelistener(new radiogroup.oncheckedchangelistener() {       @override       public void oncheckedchanged(**radiogroup group**, int checkedid) {         switch (checkedid) {           case r.id.radiobutton2:             group.setorientation(linearlayout.horizontal);             break;           case r.id.radiobutton1:             group.setorientation(linearlayout.vertical);             break;         }       }     });  } 

thanks help

radiogroup.oncheckedchangelistener interface, , creating annonymouse inner class on your:

//take note @ key word new  setoncheckedchangelistener(new radiogroup.oncheckedchangelistener{//overriden methods here}); 

that's how gets instantiated in code. hope helps.

update

1. reference observer pattern

2. custom action listener example