How to avoid a Toast if there’s one Toast already being shown

I’ve tried a variety of things to do this. At first I tried using the cancel(), which had no effect for me (see also this answer).

With setDuration(n) I wasn’t coming to anywhere either. It turned out by logging getDuration() that it carries a value of 0 (if makeText()‘s parameter was Toast.LENGTH_SHORT) or 1 (if makeText()‘s parameter was Toast.LENGTH_LONG).

Finally I tried to check if the toast’s view isShown(). Of course it isn’t if no toast is shown, but even more, it returns a fatal error in this case. So I needed to try and catch the error.
Now, isShown() returns true if a toast is displayed.
Utilizing isShown() I came up with the method:

    /**
     * <strong>public void showAToast (String st)</strong></br>
     * this little method displays a toast on the screen.</br>
     * it checks if a toast is currently visible</br>
     * if so </br>
     * ... it "sets" the new text</br>
     * else</br>
     * ... it "makes" the new text</br>
     * and "shows" either or  
     * @param st the string to be toasted
     */

    public void showAToast (String st){ //"Toast toast" is declared in the class
        try{ toast.getView().isShown();     // true if visible
            toast.setText(st);
        } catch (Exception e) {         // invisible if exception
            toast = Toast.makeText(theContext, st, toastDuration);
            }
        toast.show();  //finally display it
    }