Head First Java sink a dot com game, where am I going wrong?

[Vic Hood]

Hi Folks,

Im trying to learn Java through HeadFirst and tried out some of their code on my own to build a sink-a -dot-com game. The game is simple, its supposed to take three user inputs and compare them as to whether they match those of the cells alloted to the dotcoms randomly.
Here's my source code

DotComBust.java

package org.self.Test;
import java.util.ArrayList;
public class DotComBust {
private GameHelper helper= new GameHelper();
private ArrayList<DotCom>dotComsList=new ArrayList<DotCom>();
private int numGuesses=0;
private void setupGame(){
// create Three separate Dot Com objects!
DotCom one=new DotCom();
one.setName("Pets.com");
DotCom two=new DotCom();
two.setName("eToys.com");
DotCom three=new DotCom();
three.setName("MSN.com");
// Add em to the list!
dotComsList.add(one);
dotComsList.add(two);
dotComsList.add(three);
//Print out to screen.
System.out.println("Your aim is to sink the three dotcoms");
System.out.println("Try to sink em in the lowest number of guesses");
// Assign the location to each of the dotcom
for(DotCom dotComSet:dotComsList){
//Setting location for one dot com at a time!
ArrayList<String> newLocation=helper.placeDotCom(3);// from Helper claSS!
dotComSet.setLocationCells(newLocation);
}
}
private void startPlaying(){
// first check if the list is empty.If not then proceed
while(!dotComsList.isEmpty()){
String userGuess=helper.getUserInput("Enter a Guess!");
//pass control to checkUserGuess
checkUserGuess(userGuess);
}
finishGame();
}
private void checkUserGuess(String userGuess){
// increment the number of guesses
numGuesses++;
String result="miss";
//System.out.println(result);
for(DotCom dotComToTest:dotComsList){
result=dotComToTest.checkYourself(userGuess);
if(result.equals("hit")){
// if hit then break;
break;
}
if(result.equals("kill")){
dotComsList.remove(dotComToTest);
break;
}
//print the result
}
System.out.println(result);
}
private void finishGame(){
// Method executed at end of game!
System.out.println("All the Dot-coms have been sunk. Your stock is worthless!!");
if (numGuesses<=18){
System.out.println("It took you only "+numGuesses+"guesses");
System.out.println("You won before running out of options!");
}
else{
System.out.println("It took you long enough"+numGuesses+"guesses");
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
DotComBust game=new DotComBust();
game.setupGame();
game.startPlaying();
}
}

and DotCom.java

package org.self.Test;
import java.util.ArrayList;
public class DotCom {
private String name;
private ArrayList<String> locationCells;
public void setLocationCells(ArrayList<String>loc){
locationCells=loc;
}
public void setName(String n){
name=n;// setter methods
}
public String checkYourself(String userGuess){
String result="miss";
// check if there's a hit by checking for index of hit value
int index=locationCells.indexOf(userGuess);
System.out.println("index of"+index);
if(index>=0){
// if hit then remove that from the list.
locationCells.remove(index);
}
if(locationCells.isEmpty()){
// once the arraylist is empty the entity has sunk
result="kill";
}
else{
// else mark a hit!
result="hit";
}
return result;
}
}

When I run DotComBust.java this is what happens

Your aim is to sink the three dotcoms
Try to sink em in the lowest number of guesses
Enter a Guess! 4
index of-1
hit
Enter a Guess! 4
index of-1
hit
Enter a Guess! 

Im pretty sure the problem is because of the element not being present in the list, then how am I being able to print hit? Any insight would be helpful, thanks!!

[dennis deems]

The if/else block that prints "hit" or "kill" should be nested inside the if block that updates the list. That way it will only execute if a hit has occurred. As it stands, this code is executed whether or not it's a hit or a miss.

[Vic Hood]

Thanks for the reply Dennis.

I moved the if/else block into the if statement, however the program still doesnt work as expected.For instance, even if an element is actually present in the 'dotcom' , the program still results in a miss ,I some how feel that Im not being able to set the locationCells correctly in DotCom.java. Any help on that would be great.

method that sets up the Game in DotComBust

private void setupGame(){
// create Three separate Dot Com objects!
DotCom one=new DotCom();
one.setName("Pets.com");
DotCom two=new DotCom();
two.setName("eToys.com");
DotCom three=new DotCom();
three.setName("MSN.com");
// Add em to the list!
dotComsList.add(one);
dotComsList.add(two);
dotComsList.add(three);
//Print out to screen.
System.out.println("Your aim is to sink the three dotcoms");
System.out.println("Try to sink em in the lowest number of guesses");
// Assign the location to each of the dotcom
for(DotCom dotComSet:dotComsList){
//Setting location for one dot com at a time!
ArrayList<String> newLocation=helper.placeDotCom(3);// from Helper claSS!
dotComSet.setLocationCells(newLocation);
for(String s:newLocation){
System.out.println("Array Location"+s);
}
}
}

 public String checkYourself(String userGuess){
String result="miss";
// check if there's a hit by checking for index of hit value
int index=locationCells.indexOf(userGuess);
System.out.println("index of"+index);// this value is always -1 , even if the arrayList contains teh element, so only misses being counted!
if(index>=0){
// if hit then remove that from the list.
locationCells.remove(index);
if(locationCells.isEmpty()){
// once the arraylist is empty the entity has sunk
result="kill";
}
else{
// else mark a hit!
result="hit";
}
}
return result;
} 

Result

Your aim is to sink the three dotcoms
Try to sink em in the lowest number of guesses
Array Locationd3
Array Locationd4
Array Locationd5
Array Locationa3
Array Locationb3
Array Locationc3
Array Locatione3
Array Locatione4
Array Locatione5
Enter a Guess! 4// this should be a hit!
index of-1
index of-1
index of-1
miss
...

[Vic Hood]

Any help folks?!

[Athira Vineeth]

hi

i think it is because

if(locationCells.isEmpty()){
// once the arraylist is empty the entity has sunk
result="kill";
}
else{
// else mark a hit!
result="hit";
}

locationCells is not empty so it is always printing hit. in the first code

after changing the if(index>=0) position ,the execution never entered into if(index>=0){ block

so the default value got printed "miss"

[dennis deems]

It's time to learn the art of debugging. You need to test your assumptions by printing things to the console (or using the debugging tool if you're using an IDE). You already know that locationCells does NOT contain userGuess. That's your starting point to focus your debugging efforts. How do things get added to the list? What are the contents of the list when you call indexOf? This is the real blood sweat and tears of programming, and only you can do it.

[Vic Hood]

Thanks Dennis and Athira!

The problem was with not looking at the code from the right perspective. Thank you for the time!