Head First Java (2nd Ed.) p. 112

[marsooka]

The instructions on page 112 are to "Drop all three classes(...) into the same directory...
my question is based on the fact that the only successful class/java-file i compiled was the one called GameHelper. What is the exact syntax and file name(s) of the other two supposed to be, i've tried many and continue to get compile errors...
the other two (saved in one .java file together, or two separate .java files) are referred to as SimpleDotCom and SimpleDotComGame.

thanks, marsooka
[ December 31, 2006: Message edited by: barclay mcdaniel ]

[Bert Bates]

Hey Barclay,

Can you tell us a little more about exactly what files you have (their exact names), what directory(ies) they are in, what compiler command you're using, and exactly what errors you're getting?

Thanks!

Bert

[Davy Kelly]

i think what they are trying to say is that the 3 classes should be in the same directory e.g. C:\Program Files\Java\jdk1.5.0_03 so that you can compile and run them you only compile the SimpleDotComTestDrive file and the rest should compile automatically

then run it.

so to re-iterate, have all 3 java files in a directory typically, where the bin file is.

save all 3 files with their Class_Name.java, here is the code:

public class SimpleDotComTestDrive 
{
public static void main(String[] args) 
{
int numOfGuesses = 0; //variable to track how many guesses a user makes
GameHelper helper = new GameHelper(); //this is a special class that has the method for getting user input (made up class)
SimpleDotCom theDotCom = new SimpleDotCom(); //instantiate a simple DotCom object
int randomNum = (int)(Math.random() * 5); //a random number for the first cell of the locations array

int[] locations = {randomNum, randomNum+1, randomNum+2}; //make an int array for the location of the DotCom (3 cnosecutive out of 7)
theDotCom.setLocationCells(locations); //invoke the setter method on the DotCom
boolean isAlive = true; //a boolean to track whether the game is still alive, to use in the while loop
 
while (isAlive == true)
{
String guess = helper.getUserInput("enter a number");
String result = theDotCom.checkYourself(guess); //invoke the check method on the DotCom object and pass it the fake guess
numOfGuesses++; //increment post count

if (result.equals("kill")) //if it is a kill set boolean to false
{
isAlive = false;
System.out.println("You took "+numOfGuesses+ " guesses");
} //end if
} //end while
} //end main method
} //end class

class SimpleDotCom 
{
int[] locationCells;
int numOfHits = 0;
 
public void setLocationCells(int[] locs)
{
locationCells = locs;
}
public String checkYourself(String stringGuess) 
{
int guess = Integer.parseInt(stringGuess); //converting the string guess to an int
String result = "miss"; //a variable to hold the result, miss is default
 
for (int cell: locationCells)//repeat with each cell in the locationCells array (each cell location of the object)
{
if (guess == cell) //compare the user guess to this element (cell) in the array
{
result = "hit";
numOfHits++;  //increment numOfHits by one
break; //break out of the for loop
}//end if
}//end for loop
if (numOfHits == locationCells.length) //we are out of the loop but is the object been hit 3 times succesfully
{
result = "kill";
}//end if
System.out.println(result); //display the result for the user
return result; // return the result back to the calling method
}//end checkYourself 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 "f4" type coords
String temp = null; //tekp string for concat
int[] coords = new int[comSize]; //current candidate coords
int attempts = 0; //current attempt 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 lpp[ (32)
{
location = (int)(Math.random()*gridSize); //get random starting point
//System.out.print("try "+location);  //cheat
int x = 0; //nth position in the dot com 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
} //end if
if (x > 0 && (location % gridLength == 0)) //out of bounds right edge
{
success = false; //failure
}//end if
}
else //found already used location
{
//System.out.print(" used "+location); //cheat
success = false; //failure
}//end outer if/ else
}//end inner while
}//end outer while
 
int x = 0; //turn location into alpha coords
int row = 0;
int column = 0;
//System.out.println("\n"); //make a new line
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.prit(" coord "+x+" = " +alphaCells.get(x=1)); //this is exactly where the dot com is located
}
//System.out.println("\n"); //new line
return alphaCells;
}
}

compile "javac SimpleDotComTestDrive.java" this will in turn compile the rest, then run it java SimpleDotComTestDrive this should run all 3 classes as the game.

davy
[ December 31, 2006: Message edited by: Davy Kelly ]

[Jeanne Boyarsky]

Barclay,
Yes, each (public) class should be in a separate file. When you compile them, be sure to compile in one step so all the classes are found.

>javac *.java

[marsooka]

thanks...
[ December 31, 2006: Message edited by: barclay mcdaniel ]