Simple HangMan game Implemented in Java

Question

This simple implementation of the HangMan game in Java is a side project, unlike the usual programs I write which are either school assignments or problems on coding websites.

It feels great to have something simple working, but I know for sure this can be improved. This only runs through the command line now, but I'm thinking of adding a lot more to this in the near future.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main {


    public static void main(String[] args) throws FileNotFoundException {

        Scanner userGuess = new Scanner(System.in);

        printTitleScreen();
        System.out.println("");
        String word = getRandomWordFromFile("/Users/kingcold/Desktop/words.txt");
        char[] wordCharArray = word.toCharArray();

        System.out.println("It's time to guess the word!");

        StringBuilder gameWord = new StringBuilder(printBlankSpaces(word));

        int successfulAttempts = 0;
        int failedAttempts = 0;
        int totalAttempts = 0;


        do {

            System.out.println("Your word looks like this: " + gameWord);
            System.out.println("Your guess: ");

            String userInput = userGuess.next();
            char charUserInput = userInput.charAt(0);

            if (isValidInput(userInput)) {
                    System.out.println("Your guess is: " + userInput);

                    if (!(containsUserInput(wordCharArray, userInput))) {

                        letterNotInWordMessage(userInput);
                        failedAttempts++;

                    } else if (containsUserInput(wordCharArray, userInput)){

                        letterInWordMessage(userInput);     
                        gameWord.setCharAt(getMatchingIndex(wordCharArray, userInput), charUserInput);
                        successfulAttempts++;

                    }

            } else {

                System.out.println("Invalid input entered. Try again.");

            }

            totalAttempts = successfulAttempts + failedAttempts;


        } while (!word.equals(gameWord.toString()));


        if (word.equals(gameWord.toString())) {
            System.out.println("Congratulations, you correctly guessed the word!");
            System.out.println("The word is " + word);
            System.out.println("You guessed the word in " + totalAttempts + " attempts");
            userGuess.close();
        }

    }

    private static void printTitleScreen() {
        System.out.println("-------------------");
        System.out.println("Welcome to Hangman!");
        System.out.println("-------------------");
    }

    private static String printBlankSpaces(String word) {
        return new String(new char[word.length()]).replace('\0', '-');
    }

    private static void letterNotInWordMessage(String letter) {
        System.out.println("The letter " + letter + " is not in the word!");
    }

    private static void letterInWordMessage(String letter) {
        System.out.println("The letter " + letter + " is in the word!");
    }

    private static int getMatchingIndex(char[] wordArray, String userGuess) {
        int index = -1;
        for (int i = 0; i < wordArray.length && (index == -1); i++) {
            if (String.valueOf(wordArray[i]).equals(userGuess)) {
                index = i;
            }
        }
        return index;
    }

    private static boolean containsUserInput(char[] wordArray, String userGuess) {
        for (int i = 0; i < wordArray.length; i++) {
            if (wordArray[i] == userGuess.charAt(0)) {
                return true;
            }
        }
        return false;
    }

    private static boolean isValidInput(String userGuess) {
        final int VALID_INPUT_LENGTH = 1;
        if (userGuess.length() == VALID_INPUT_LENGTH  && Character.isLetter(userGuess.charAt(0))) {
            return true;
        } 
        return false;
    }

    private static String getRandomWordFromFile(String fileName) throws FileNotFoundException {

        File file = new File(fileName);
        Scanner fileScanner = new Scanner(file);
        String fileContents = "";

        while(fileScanner.hasNextLine()) {
            fileContents = fileContents.concat(fileScanner.nextLine() + "\n");
        }

        fileScanner.close();
        String[] fileContentArray = fileContents.split("\n");
        return fileContentArray[(int) (Math.random() * fileContentArray.length)];

    }


}

Answer 1

Let’s start with your utility methods.

---

printBlankSpaces(String word)

This method returns a new String; It does not do any printing. It needs a better name...

---

getMatchingIndex(char[] wordArray, String userInput)

You repeatedly turn each character of wordArray[] into a String using String.valueOf(...). It would be better to turn the userInput into a character before the loop starts (using .charAt(0)), and just do a simple comparison in the loop with that character.

It would be even better to pass in a char userInput, instead of a String.

Instead of && (index == -1) in your loop condition, just break; out of the loop after you do the assignment index = i;, or even simplier, return i; and you could remove the index variable entirely.

---

containsUserInput(char[] wordArray, String userInput)

Instead of extracting .charAt(0) in every iteration of the loop, do it before the start of the loop and save it in a local variable. Or even better, like above, pass in char userInput.

You aren’t using the loop index other than for retrieving the character wordArray[i]. This is a sign you could use an enhanced for-loop:

char userChar = userInput.charAt(0);
for (char letter : wordArray) {
   if (letter == userChar) {
       return true;
   }
}
return false;

Or even simpler, the entire method could be one statement, leveraging the function above:

return getMatchingIndex(wordArray, userInput) >= 0;

---

isValidInput(String userGuess)

The construct if (condition) return true; else return false; can be re-written as return condition;. You don’t need the if statement.

---

getRandomWordFromFile(String fileName)

You are doing a lot of work to get a random line from the file. First, you are reading the file, line-by-line. Then, you concatenate all the lines together! Finally you split the concatenation back into the individual lines!

If you simply stored each line as you read it into a List<String>, you would be able to skip the concatenation and wouldn’t need to split later.

In fact, reading all the lines of a file into a List<String> is such a common operation, there is a standard method for it. List<String> Files.readAllLines(Path path).

With that, the function could be reduced to two lines:

List<String> lines = Files.readAllLines(Paths.get(fileName));
return lines[ ThreadLocalRandom.current().nextInt(lines.size()) ];

That skips over a lot of fine points. Most important is ensuring all file resources are properly closed, even in the face of exceptions. The “try-with-resources” statement is best used for that:

File file = new File(fileName);
List<String> lines = new ArrayList<>();
try(Scanner scanner = new Scanner(file)) {
    while(scanner.hasNextLine()) {
        lines.add( scanner.nextLine());
    }
}

All that is done for you with the one readAllLines() call.

---

main

charUserInput is not used. As mentioned above, many of your methods would be easier to write if they were given a single character, instead of a String ... and you have this unused character variable that would be perfect for that...

You tests if (!(containsUserInput(wordArray, userInput))) { ... } followed immediately by else if (containsUserInput(wordArray, userInput)) { ... }. Those tests conditions are - literally - opposites of each other; if one is true, the other must be false, and vis-versa. Instead of repeating the test, both in code and in CPU time, just use an else

if (!containsUserInput(wordArray, userInput)) {
   ...
} else {
   ...
}

I’ve removed the unnecessary ( )’s. You can improve this further by switching the order of the then-else clauses, and removing the ! operator.

if (containsUserInput(wordArray, userInput)) {
    ... guess is correct code ...
} else {
    ... guess is incorrect code ...
}