import java.net.*;import java.io.*;public class KnockKnockProtocol {    private static final int WAITING = 0;    private static final int SENTKNOCKKNOCK = 1;    private static final int SENTCLUE = 2;    private static final int ANOTHER = 3;    private static final int NUMJOKES = 5;    private int state = WAITING;    private int currentJoke = 0;    private String[] clues = { "Turnip", "Little Old Lady", "Atch", "Who", "Who" };    private String[] answers = { "Turnip the heat, it's cold in here!",                                 "I didn't know you could yodel!",                                 "Bless you!",                                 "Is there an owl in here?",                                 "Is there an echo in here?" };    public String processInput(String theInput) {        String theOutput = null;        if (state == WAITING) {            theOutput = "Knock! Knock!";            state = SENTKNOCKKNOCK;        } else if (state == SENTKNOCKKNOCK) {            if (theInput.equalsIgnoreCase("Who's there?")) {                theOutput = clues[currentJoke];                state = SENTCLUE;            } else {                theOutput = "You're supposed to say \"Who's there?\"! " +			    "Try again. Knock! Knock!";            }        } else if (state == SENTCLUE) {            if (theInput.equalsIgnoreCase(clues[currentJoke] + " who?")) {                theOutput = answers[currentJoke] + " Want another? (y/n)";                state = ANOTHER;            } else {                theOutput = "You're supposed to say \"" + 			    clues[currentJoke] + 			    " who?\"" + 			    "! Try again. Knock! Knock!";                state = SENTKNOCKKNOCK;            }        } else if (state == ANOTHER) {            if (theInput.equalsIgnoreCase("y")) {                theOutput = "Knock! Knock!";                if (currentJoke == (NUMJOKES - 1))                    currentJoke = 0;                else                    currentJoke++;                state = SENTKNOCKKNOCK;            } else {                theOutput = "Bye.";                state = WAITING;            }        }        return theOutput;    }}