/**  * 退出  */ @Override public boolean dispatchKeyEvent(KeyEvent event) {   if (event.getKeyCode() == KeyEvent.KEYCODE_BACK       && event.getAction() == KeyEvent.ACTION_DOWN       && event.getRepeatCount() == 0) {           //具體的操作代碼   }   return super.dispatchKeyEvent(event); } 

@Override public void onBackPressed() {   super.onBackPressed(); } 

/**  * Called when the activity has detected the user's press of the back  * key. The default implementation simply finishes the current activity,  * but you can override this to do whatever you want.  */ public void onBackPressed() {   finish(); }