Android 实现再按一次后退键退出应用程序

private boolean isexit = false; private boolean hastask = false;Timer texit = new Timer();

TimerTask task = new TimerTask() {public void run() {isexit = false;hastask = true;}};@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){//DialogAPI.showExit(this);if(isexit == false){isexit = true;Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();if(!hastask) {texit.schedule(task, 2000);}}else{finish();System.exit(0);}return false;}return super.onKeyDown(keyCode, event);}