Android之Menu菜单 onCreateOptionsMenu使用Menu按键显示不了问题

@Override
public boolean  onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
MenuInflater menuInflater = this.getMenuInflater();
menuInflater.inflate(R.menu.menu, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
int selectId = item.getItemId();
switch (selectId) {
case R.id.new_dir:
newDir();
break;
case R.id.del:
delFileSelected();
break;
case R.id.move:
moveDir();
break;
case R.id.setting:
setting();
break;
case R.id.exit:
exit();
break;
case R.id.adbout:
about();
break;
}
return true;
}