Android :: Using Cancel Method From Toast In Main UI Thread

I want to cancel a Toast to show the next one. This is the description of the behavious I want, when I select one element in the menu i display a toast from the actuel menu element, but if i switch from one element to an other quickly i'm creating a list of Toast to display. So i need to cancel the previous one but i never succed. This is an extract of my code: public class MainActivity extends TabActivity

private Toast toast; private String toastMsg;
private void toast(){ if(toast!=null){ toast.cancel(); } toast = Toast.makeText(MainActivity.this, toastMsg,Toast.LENGTH_SHORT);
toast.show(); } }