java - Android: Implementing a Back Button from a class -

okay, here problem. i'm working on android app , learning android @ same time, of times errors. normaly can fix them after researching bit, i'm getting stuck in point.

i'm trying make button every activity in app, thought making "backbutton" class, can instanciate every time want to. here backbutton code:

import android.content.intent; import android.view.view; import android.widget.button; import android.app.activity;      public class backbutton extends activity implements view.onclicklistener{          public static button backbutton;          // defining button         public backbutton() {              backbutton = (button) findviewbyid(r.id.bback);              backbutton.setonclicklistener(this);          }          //to button         public static button getbackbutton() {             return backbutton;         }           // onclicklistener         public void onclick(view v) {                  try {                     class mainactivityclass = class.forname("eu.lafarga.treballderecerca.mainactivity");                     intent mainactivityintent = new intent(backbutton.this, mainactivityclass);                      startactivity(mainactivityintent);                 } catch (classnotfoundexception e) {                     e.printstacktrace();                 }finally {                     // save things we've done.                  }          }      } 

so, how should implement in activity? i'm doind wrong? (sure i'm lol)

personally, suggest not doing this. think overriding button in each activity safer, more flexible, , easy, if not easier. chances are, aren't going want return mainactivity app grows because won't expected action users when hit button. override button in activities need , run code

    @overrride     public void onbackpressed(view v) {      // save data first        intent mainactivityintent = new intent(currentactivityname.this, mainactivityclass);        startactivity(mainactivityintent);       super.onbackpressed(); } 

you can use flags such flag_activity_clear_top if want remove activities between current 1 , target activity(here mainactivity) calling setflags(intent.flag_activity_clear_top)