Android clicks the Back key twice in a row to exit the program.

Train of Thought: record the time of the last click. Compared with the time of this click, exit when the two time intervals are less than a certain value; otherwise, the system prompts "exit the program again ", update the last click time at the same time

 

Private long firstTime = 0; @ Override public boolean onKeyUp (int keyCode, KeyEvent event) {// TODO Auto-generated method stub switch (keyCode) {case KeyEvent. KEYCODE_BACK: long secondTime = System. currentTimeMillis (); if (secondTime-firstTime> 2000) {// if the interval between two buttons is greater than 2 seconds, do not exit Toast. makeText (this, "exit the program again", Toast. LENGTH_SHORT ). show (); firstTime = secondTime; // update firstTime return true;} when the else {// two buttons are less than 2 seconds, exit the application System. exit (0);} break;} return super. onKeyUp (keyCode, event );}