[midas]

 public static char readLineNonwhiteChar()
    {
        boolean done = false;
        String inputString = null;
        char nonWhite = ' ';//To keep the compiler happy.

        while (! done)
        {
            inputString = readLine();
            inputString = inputString.trim();
            if (inputString.length() == 0)
            {
                System.out.println(
                                "Your input is not correct.");
                System.out.println("Your input must contain at");
                System.out.println(
                              "least one nonwhitespace character.");
                System.out.println("Please, try again.");
                System.out.println("Enter input:");
            }
            else
            {
                nonWhite = (inputString.charAt(0));
                done = true;
            }
        }

        return nonWhite;
    }

Das hier benutzen wir auf der Uni, hoffe das hilft dir.