安卓双击返回退出源代码

安卓双击返回退出源代码

public boolean onKeyDown(int keyCode, KeyEvent event) {
         if (keyCode == KeyEvent.KEYCODE_BACK) {
                 if ((System.currentTimeMillis() - mExitTime) > 2000) {
                         Object mHelperUtils;
                         Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
                         mExitTime = System.currentTimeMillis();
                 } else {
                         finish();
                 }
                 return true;
         }
         return super.onKeyDown(keyCode, event);
 }