java - Back button doesn't work -

i have application 2 activities. in first activity possible start second clicking button.

@override public void onclick(view v) {     intent intent = new intent(firstactivity, secondacitivity.class);     startactivity(intent); } 

bizarrely, clicking button in second activity doesn't bring me back. thought such basic behavior implemented don't have it. in other apps wrote there never has arisen such problem.

of course in class of first activity have

@override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     ...     firstactivity = this;     ... } 

have done intercept key event?

for example:

@override public boolean onkeydown(int keycode, keyevent event) { if(keycode == keyevent.keycode_back){     return true; } return super.onkeydown(keycode, event); } 

or

@override public void onbackpressed() { //not invoke super.onbackpressed(); }