Why does my 'word' variable not update at the end of my Hangman program?

Question

The following is only part of my code. Im having an issue in my hangman game where the "hanging" method doesn't seem to be working. For example if the word to guess was 'banana' and you guess 'a' the word would then appear as 'a_a_a' but instead what I'm getting is just '_____'. Using system.out.print I found out that at the end of the hanging method 'word' does actually equal '_a_a_a' but when it prints again in the main method it goes back to just underscores. Anyone sure why this is happening?

public class Hangman
{
    private static int lives = 7;
    
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        
        System.out.println("Player 1, please enter a word.");
        
        String str = sc.nextLine();
        String word = UnderscoreWord(str);
        char[] ar = word.toCharArray();
        
        while(lives > 0)
        {
            System.out.println("Player 2, please guess a letter");
            System.out.println(word);
            
            char guess = sc.next(".").charAt(0);
            
            hanging(guess, word, ar, str);
        }
        
        sc.close();
    }
    
    public static void hanging(char guess, String word, char ar[], String str)
    {
        String newWord = "";
        
        for(int i = 0; i < word.length(); i++)
        {
            if(str.charAt(i) == guess)
            {
                ar[i] = guess;
                    
                newWord += ar[i];
            }
            else if(word.charAt(i) != '_')
            {
                newWord += str.charAt(i);
            }
            else
            {
                newWord += "_";
            }
        }
        
        if (word.equals(newWord))
        {
            System.out.println("Wrong!");
            lives--;
            alive(lives);
        }
        else
        {
            word = newWord;
        }
      
        if (word.equals(str)) 
        {
            System.out.println("You win!");
        }
    }
    
    public static String UnderscoreWord(String str)
    {
        String underscore = new String("");
        int length = str.length();
        
        for(int i = 0; i < length; i++)
        {
            underscore += "_";
        }
        
        return underscore;
    }
}

You don't have a String field anywhere, and that is what you need. If your program is nothing but static methods, give your class a static field that can be updated — DontKnowMuchBut Getting Better, Jan 02 '21 at 15:47
Does this answer your question? [Is Java “pass-by-reference” or “pass-by-value”?](https://stackoverflow.com/questions/40480/is-java-pass-by-reference-or-pass-by-value) — knittl, Jan 02 '21 at 15:56
A field is just a variable that has been declared inside of the class, not inside of any method or constructor. If it is static, then it is visible to all your static methods. You already have a "lives" int field. — DontKnowMuchBut Getting Better, Jan 02 '21 at 16:02
No, you should not set the variables as static variables. I don't know why anyone gives that advice. When your code is non-trivial, static variables and methods can easily interfere with one another. — Gilbert Le Blanc, Jan 02 '21 at 17:02

score 0 · Answer 1 · answered Jan 02 '21 at 15:57

When you pass the String word to your hanging() method, the local word object in the method starts out as a reference to the object passed in from main(). However, when you set word = newWord, the local word variable is updated to point to a new object (same as newWord. The original String word (passed from main()) is not updated.

Since your methods are all static you could have a static variable word that is updated. Or the new word could be returned from hanging()

return newWord;

score 0 · Answer 2 · answered Jan 02 '21 at 15:58

You're just reassigning the method's String word in the hanging method but the method returns nothing. You should return newWord at the end of the method and assign it appropriately in the main method where you call it.

word = hanging(guess, word, ar, str);

Why does my 'word' variable not update at the end of my Hangman program?

2 Answers2