DotComBustGame in HFJ -- not working; can't figure out what I've missed

[Christopher Laurenzano]

I've typed the code for the DotComBust Game in HFJ, and it all compiled, but for some reason, I'm not getting the string prompt to enter a guess or the result of my guess (hit or kill). For those familiar with the game, here's the code. Can someone point out what's wrong? My head is swimming/ spinning from trying to figure it out.

import java.util.*;

public class DotCom {

    private ArrayList<String> locationCells;
    private String name;
    //private int numOfHits=0;
    //don't need that now;

    public void setLocationCells(ArrayList<String> loc) {
         locationCells = loc;
    }
   
    public void setName (String n) {
         name=n;
    }

    public String checkYourself(String userInput) {
          
          String result = "miss";
          
               int index=locationCells.indexOf(userInput);
                
               if (index >=0) {
                   locationCells.remove(index);
                   
                   if (locationCells.isEmpty() ) {
                      result = "kill";
                   } else {
                      result = "hit";
                   }//close if
                 
                }//close  if
 
            return result;
      }//close method
 }//close class          

          
         

import java.util.*;

public class DotComBust {

    private GameHelper helper=new GameHelper ();
    private ArrayList<DotCom> dotComsList = new ArrayList <DotCom>();
    private int numOfGuesses = 0;

    public void setUpGame() {
      //first make some dot coms and give them locations
      DotCom one = new DotCom();
      one.setName("Pets.com");
      DotCom two=new DotCom();
      two.setName("e.Toys.com");
      DotCom three=new DotCom();
      three.setName("Go2.com");
      dotComsList.add(one);
      dotComsList.add(two);
      dotComsList.add(three);

      System.out.println("Your goal is to sink three dot coms.");
      System.out.println("Pets.com, eToys.com, Go2.com");
      System.out.println("Try to sink them all in the fewest number of guesses");

      for (DotCom dotComToSet : dotComsList) {
           ArrayList<String> newLocation = helper.placeDotCom(3);
           dotComToSet.setLocationCells (newLocation);
           } //close for loop
    }//close setUpGame Method

private void startPlaying () {
     while (!dotComsList.isEmpty ()) {
          String userGuess = helper.getUserInput ("Enter a guess");
          checkUserGuess (userGuess);
     }//close while
       finishGame();
}//close startPlaying method


private void checkUserGuess (String userGuess) {
   
       numOfGuesses ++;
       String result = "miss";
       
       for (DotCom dotComToTest : dotComsList) {
            result = dotComToTest.checkYourself (userGuess);
            if (result.equals ("hit")) {
                break;
            }
            if (result.equals ("kill")) {
                break;
            }
        }//close for
        System.out.println(result);
}//close method

private void finishGame () {
     System.out.println("All Dot Coms are dead! Your stock is now worthless.");
     if (numOfGuesses <=18) {
         System.out.println ("It only took you  " + numOfGuesses+ " guesses.");
         System.out.println(" You got out before your options sank.");
     } else {
         System.out.println("Took you long enough. " +numOfGuesses + " guesses.");
         System.out.println("Fish are dancing with your options.");
      }
}//close method

public static void main (String args []) {
     DotComBust game = new DotComBust();
     game.setUpGame();
     game.startPlaying();
     }//close method
} 



    

import java.io.*;
import java.util.*;

public class GameHelper {
   private static final String alphabet = "abcdefg";
   private int gridLength = 7;
   private int gridSize = 49;
   private int [] grid = new int [gridSize];
   private int comCount = 0;

   public String getUserInput (String prompt) {
      String inputLine = null;
      System.out.print (prompt + " ");
      try { 
         BufferedReader is = new BufferedReader (
            new InputStreamReader (System.in));
         inputLine = is.readLine();
         if (inputLine.length() == 0) return null;
       } catch (IOException e) {
          System.out.println ("IOException: " + e);
       }
     return inputLine.toLowerCase();
}


  public ArrayList<String> placeDotCom (int comSize) {
        ArrayList<String> alphaCells = new ArrayList <String> (); 
        String [] alphacoords = new String [comSize];          // holds 'f6' type coords
        String temp = null; 	                               // temporary String for concat
        int [] coords = new int [comSize];                     //current candidate coords
        int attempts = 0;                                      // current attempts counter
        boolean success = false;                               //flag = found a good location?
        int location = 0;                                      //current starting location

        comCount++;                                            // nth dot com to place
        int incr = 1;                                          // set horizontal increment
        if ((comCount  % 2) == 1) {                            // if odd dot com (place vertically)
            incr = gridLength;                                 // set vertical increment
        }

while ( ! success & attempts++ < 200) {                        // main search loop
       location = (int)  (Math.random () * gridSize) ;         // get random starting point
       //System.out.print (" try " + location);  
       int x = 0;                                              //nth position in dotcom to place
          success = true;                                      //assume success
          while (success && x < comSize) {                     // look for adjacent unused spots
               if (grid [location] == 0) {                     // if not already used
               coords[x++] = location;                         // save location
               location += incr;                               // try 'next' adjacent
               if (location >= gridSize) {                     // out of bounds - 'bottom'
                   success = false;                            // failure
               }
               if (x > 0 && (location % gridLength == 0)) {    // out of bounds - right edge
                   success = false; 
                }                                              // failure
                }  else { 
                         // System.out.print (" used " + location ;
                         success = false;                      // failure
                }
           }
}                                                              // end while

int x = 0;                                                     // tour location into alpha coords
int row = 0;                                                           
int column = 0;
// System.out.println ("\n");
while ( x< comSize); {
     grid[coords[x]] = 1;                                      // mark master grid pts as 'used'
     row = (int) (coords[x] / gridLength);                     // get row value
     column = coords[x] % gridLength;                          // get numeric column value
     temp = String.valueOf(alphabet.charAt(column));           //convert to alpha
     
      alphaCells.add(temp.concat (Integer.toString(row))); //
      x++;
      // System.out.print (" coord "+x+ " = " alphaCells.get (x-1));
     }
      // System.out.println ("\n");

     return alphaCells;
    }
}    

The GameHelper code was ready bake, so if there's a problem somewhere in the getUserInput () method, I'm not seeing it, because I just typed it in an compiled it (it's ahead of what the chapter is teaching). It's supposed to prompt a guess with "enter a guess" and return a result of hit or kill, but after the instructions display, the cursor just blinks and when I enter a guess, nothing happens.

It's probably something small I missed, but I don't see it.

[Campbell Ritchie]

Please don't use so many spaces before your //comments; that makes the code really difficult to read. You will have to use the "preview" button to see the formatting. Which page is this game on? HFJ seems to have several dot-com games in.

Don't know. You are going to have to put some print statements in, so as to follow the flow through your application. Example, new line 20½ in your setUpGame method, which ought to tell you there are 3 members:

System.out.printf("In setUpGame method: The array list contains %d members%n" dotComList.size()); //test

New line 27½ similar, but see how many members there are in the newLocation list. You will probably find it prints 1 regardless. Are you really supposed to create a new List every time you traverse that loop?
Similarly you can put print statements into the other methods and follow the control flow. A standard debugging technique. The debuggers on IDEs do the same sort of thing, but are quicker.

[Rob Acraman]

In GameHelper line 41, you're missing an ampersand. I haven't tested it, but maybe that's sending it into an infinite loop.

[Campbell Ritchie]

I think the single & is intended. You have to increment the counter, so using a single & ensures both halves of the expression are evaluated.

Actually a && would make little difference; once you get false to the left of it the loop will terminate. You might get a guess count one less, but I shall leave you to work that out.

[Christopher Laurenzano]

I don't fully understand the code - some of the code the book hasn't gotten to yet; it simply said (tongue in cheek ) 'back slowly away from this code, except to type it in and compile it.' So at this point I wouldn't know where to begin to deciper/debug it. Like I said, it compiles fine, but after the instructions are displayed, the cursor just sits there, no prompt to enter the guess, and won't display a result when I enter a guess. I'm guessing the problem is somewhere in the getUserInput() method, but I'm not sure exactly where. I typed everything in correctly, so perhaps the problem is the code itself, and it's something I not able to detect because I don't know enough?

P.S. Sorry about the spaces, I was following the format in the book.

[Janeice DelVecchio]

You should go to the website and download the GameHelper class. If you just have a typo in the GameHelper then it will work. Be sure to comment out the package information on the top.

If it doesn't work after that, you know it's your code... i.e. the parts you should know how they work. I'll see what I can do with it, but I would start there.

[Christopher Laurenzano]

Can you tell me which website -- do you mean wickedly smart or the HFJ website (the Head First Series website). There were some downloads there but the were only the DotCom and DotComBust class. I couldn't find the GameHelper class for it on that site.

If you mean wickedly smart website, then there was a link to a download for some JAR files. I downloaded it, but when I tried to open it, it said "The Java JAR file "codeKitechesTiger-1.jar" could not be launched. Check the Console for possible error messages." I'm unfamiliar with JAR files (haven't gotten there yet).

P.S. I found the code online (not the headfirstlabs site) and just copied it into a file. It works now, so I guess I had some kind of typo with my code that I couldn't see. Doh!

I went to the headfirstlabs site and found that link, but it only downloaded the DotCom and DotComBust code.

[Janeice DelVecchio]

http://headfirstlabs.com/books/hfjava/

Scroll down and there's code by chapter....