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Thread: Troubles with toString and static and non-static

  1. #1
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    Default Troubles with toString and static and non-static

    Ok, in this assignment I have to write the code for a game that involves picking up and putting down stones in the right combination in order to unlock the treasure chest.

    We've been advised that it only needs 4 classes i.e Player, Game, TreasureChest and Stones

    My problem comes when I try to get the Game class to run a toString method that when it's finished should return something like this "Jack(0) #(1) @(2) %(3) $(4) Treasure/6\(5)"

    This is what my code looks like for the Game class so far:

    import java.util.Scanner;
    public class Game
    {
       private int maxMoves;
       private int combination;
       private String name;
       private TreasureChest chest;
       private Player player;
     
     
       public Game()
       {
           Game game1 = new Game();
           Scanner keyboard = new Scanner(System.in);
           System.out.print("Enter combination for the treasure chest (5-10): ");
           int combination = keyboard.nextInt();
           keyboard.nextLine();
           chest = new TreasureChest(combination);
           System.out.print("Enter maximum allowed moves: ");
           int maxMoves = keyboard.nextInt();
           keyboard.nextLine();
           System.out.print("Enter player name: ");
           String name = keyboard.next();
           keyboard.nextLine();
           game1.toString();
     
       }
     
       public String toString()
       {
           return name + "";
       }
     
    }

    I still need to add the other information that the toString method is supposed to return, but I can't get it to return even the name. When I try to initialise the Game class it is supposed to ask for the combination, max moves and player name. Instead I get the error "java.lang.StackOverflowError:null"

    Any pointers?


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Troubles with toString and static and non-static

    I'm not really sure what this has to do with toString or the static keyword.

    In your Game constructor, you create a new Game, which calls the Game constructor, which creates a new Game, which...

    Hint: Put a System.out.println("here"); or something as the first line in your Game constructor.
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  3. #3
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    Default Re: Troubles with toString and static and non-static

    Ok, that makes sense. If I remove that first line of code what do I need to change the "game1.toString(); line to for the method to actually run? That was where the static and non-static issues come from.

    If I change it to Game.toString(); I get the error message "non-static method toString() cannot be referenced from a static context."

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    Default Re: Troubles with toString and static and non-static

    Quote Originally Posted by BadgerWatch View Post
    Ok, that makes sense. If I remove that first line of code what do I need to change the "game1.toString(); line to for the method to actually run? That was where the static and non-static issues come from.

    If I change it to Game.toString(); I get the error message "non-static method toString() cannot be referenced from a static context."
    When you're in the constructor, you're already "in" an instance of Game, so you don't have to refer to a game instance at all. You could use this.toString(), but the "this" part is implied, so simply calling toString() will do it. Calling Game.toString() is looking for a static method called toString, which you don't have.

    But also, you're not doing anything with the String returned from the toString() method. I assume you want to print it out or something?
    Last edited by KevinWorkman; September 21st, 2011 at 08:21 AM.
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    Default Re: Troubles with toString and static and non-static

    Oh of course. Yeah eventually, once I get the rest of the code up to scratch it is supposed to print out "Jack(0) #(1) @(2) %(3) $(4) Treasure/6\(5)" to show the player what the game situation is.

    Thanks for the quick responses I'll get back into it and see how it goes ^_^

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    Default Re: Troubles with toString and static and non-static

    Cool, glad you got it sorted.
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  7. The Following User Says Thank You to KevinWorkman For This Useful Post:

    BadgerWatch (September 21st, 2011)

  8. #7
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    Default Re: Troubles with toString and static and non-static

    I'm back -_-

    When I try to get the toString to return the "name" all it returns is null.

     
    import java.util.Scanner;
    public class Game
    {
       private int maxMoves;
       private int combination;
       private String name;
       private TreasureChest chest;
       private Player player;
     
     
       public Game()
       {
           Scanner keyboard = new Scanner(System.in);
           System.out.print("Enter combination for the treasure chest (5-10): ");
           int combination = keyboard.nextInt();
           keyboard.nextLine();
           chest = new TreasureChest(combination);
           System.out.print("Enter maximum allowed moves: ");
           int maxMoves = keyboard.nextInt();
           keyboard.nextLine();
           System.out.print("Enter player name: ");
           String name = keyboard.next();
           keyboard.nextLine();
           System.out.println(toString());
           turn();
           String move = keyboard.nextLine();
           move.charAt(0);
     
       }
     
       public String toString()
       {
           return "" + name + "string1" + "string2" + "string3";
       }
     
       public void turn()
       {
           System.out.print("Move (l/r/p/d) : ");
       }
    }

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    Default Re: Troubles with toString and static and non-static

    The reason is, you have a "name" variable already declared in the class private members.
    You declare it again
    String name = keyboard.next();
    here.
    So, your name is in this variable. And when toString() tries to get value, it goes to the private variable of the class which is null.
    Note: Remove the String keyword from
    String name = keyboard.next();
    this statement and hopefully it will work all fine.

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