a, abab, aabbab, baab, <the empty string>

My solution was written in JAVA and consists of approximately 80 lines of code. Please feel free to comment on my code. Are there things that I could have done better? Are there things that I could explain further. Remember this is my code, and that I have displayed it here for others to learn from. Don’t simply copy it and call it your own. I own copyright, and because I show the code does not mean that I have given up my rights to this code.

 1  /**
 2   * EVEN-EVEN Simulation
 3   * Written By: Dallin Jones
 4   * CS3240 - Computational Theory
 5   * For use by him and his professor (and person he dubs as the grader)
 6   * It is not to be used by any one else. 
 7   */
 8
 9  package com.dallinjones.cs3240.p1;
10
11  import java.io.*;
12
13  public class AppLauncher {
14    /**
15     * The transtion table works as follows:
16     *   Each row in the table represents a state from 0-3
17     *   State 0 Even-Even (Accepting state defined by [0][0]
18     *   State 1 Even-Odd (Not-Accepting state defined by [1][0]
19     *   State 2 Odd-Even (Not Accepting state defined by [2][0]
20     *   State 3 Odd-Odd (Not Accepting state defined by [3][0]
21     *   
22     *   Columns 1 and 2 show which state to move to for input in that column
23     *   The input given is currentState - 'a' + 1 (this shoudl give us 1 or 2
24     *   for a or b respectivley)  
25     */
26    private static int[][] transitionTable = {
27      {1, 1, 2},
28      {0, 0, 3},
29      {0, 3, 0},
30      {0, 2, 1}
31    };
32
33    public static int simulateEvenEven(String testString) {
34      int currentState = 0;
35      testString = testString.toLowerCase();
36      char[] brokenUp = testString.toCharArray();
37
38      for (int i = 0; i < brokenUp.length; i++) {
39        if ( (brokenUp[i] == 'a') || (brokenUp[i] == 'b') ) {
40          currentState = transitionTable[currentState][brokenUp[i] - 'a' + 1];
41        } else {
42          return 0;
43        }
44      }
45      return transitionTable[currentState][0];
46    }
47
48    /**
49     * @param args
50     */
51    public static void main(String[] args) {
52      boolean exit = false;
53      BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
54      String inputLine = null;
55
56      System.out.println("EVEN-EVEN Simulation\nDallin Jones\nCS3240\n");
57      while (!exit) {
58        try {
59          System.out.print("Type 'exit' to quit or enter a string >");
60          inputLine = input.readLine();
61          if (inputLine.equals("exit")) {
62            exit = true;
63          } else {
64          int returnValue = simulateEvenEven(inputLine);
65            System.out.print("'" + inputLine + "' ");
66            if (returnValue != 0) {
67              System.out.println("- Valid string");
68            } else {
69              System.out.println("- Invalid string");
70            }
71          }
72        } catch (IOException ioe) {
73          System.out.println("IOExpection caught while trying to read an input string!\n");
74          System.exit(1);
75        }
76      }
77      System.out.println("Exiting Program...");
78    }
79  }