Troubled with how and where to implement if/else statements

I am almost finished creating a hangman game in Java, although I am having difficulty with one last part. I want to make it so the program checks if all the letters of the word have been guessed correctly and if so, the game prints a message saying they have won, the game ends and the program goes to the do while loop in the main class asking if they would like to play again. If not however, the game continues until this point or if all 5 guesses have been used - to which again, it is sent to the do while loop in order to restart the game and not simply terminate the program.

The problem is I am unsure how and where exactly to structure the if and else statements in order to do so.

Any help would be greatly appreciated, if I can provide further information to help narrow anything down please ask too, thank you in advance.

Instantiable Class

public class Hangman {

    private char letterGuess;
    private int numberLives;
    private String outputWord, endMessage;
    private final String hiddenWord;
    private final StringBuffer swapBuffer = new StringBuffer();

    
    public Hangman() {
        letterGuess = ' ';
        numberLives = 5;
        hiddenWord = "java";
        outputWord = "";
        endMessage = "";
        for (int i = 0; i < hiddenWord.length(); i++) {
            swapBuffer.append("*");
        }
    }

    
    public void setLetterGuess(char letterGuess) {
        this.letterGuess = letterGuess;
    }

    
    public void compute() {
        boolean letterFound = false;
        for (int i = 0; i < hiddenWord.length(); i++) {
            if (letterGuess == hiddenWord.charAt(i)) {
                swapBuffer.setCharAt(i, letterGuess);
                letterFound = true;
            }
        }

        if (!letterFound) numberLives--;
        outputWord = swapBuffer.toString();
    }

    
    public int getNumberLives() {
        return numberLives;
    }

    public String getHiddenWord() {
        return hiddenWord;
    }

    public String getOutputWord() {
        return outputWord;
    }

    public String getEndMessage() {
        return endMessage;
    }
}

Main Class

import javax.swing.*;
public class HangmanApp {

    public static void main(String[] args) {

        char letterGuess;
        int numberLives;
        String hiddenWord, outputWord, endMessage, restartGame;

        do {
            Hangman myHangman = new Hangman();

            JOptionPane.showMessageDialog(null, "Welcome to Java Hangman!");
            JOptionPane.showMessageDialog(null, "In this game, a word will be printed to you in asterisks - each letter will be revealed upon a correct guess!");
            JOptionPane.showMessageDialog(null, "You have 5 lives for the game, the game will end if you make too many incorrect guesses!");

            for (int i = 0; i < 10; i++) {
                hiddenWord = myHangman.getHiddenWord();
                numberLives = myHangman.getNumberLives();
                JOptionPane.showMessageDialog(null, "You currently have " +numberLives+ " lives!");
                letterGuess = JOptionPane.showInputDialog(null, "Now, please enter a letter : ").charAt(0);
                myHangman.setLetterGuess(letterGuess);

                myHangman.compute();

                outputWord = myHangman.getOutputWord();
                JOptionPane.showMessageDialog(null, "The word so far is  :  " +outputWord);
            }

            numberLives = myHangman.getNumberLives();
            JOptionPane.showMessageDialog(null, "You have finished the game with :  " +numberLives+ " lives!");
            restartGame = JOptionPane.showInputDialog(null, "Would you like to play again?");

        }

        while (restartGame.equalsIgnoreCase("Yes"));

    }
}

Here's the way I see it. After you call myHangman.compute();, you want to check to see if the player has either won the game or run out of lives. Each of these is a separate test using an if expression. There is no else part because if the test fails, the game just goes on.

If one of these conditions is recognized, then you want to display a message, and then you want to exit the current game loop so the user will be asked if they want to play another game. The way to do this is with the break statement.

One issue you have is that you don't have a way in your main game loop to ask the Hangman class if the user has guessed the whole word. To be able to do this, you can add this method to the bottom of your Hangman class:

public boolean getAllLettersFound() {
    return outputWord.indexOf('*') < 0;
}

This method checks to see if there are any * in outputWord. If not, then the user has guessed all the letters. So with this method added, the main loop can query the Hangman object to find out if the player has won.

To put this all together, you need to add the two condition checks to your main game loop, right after you call myHangman.compute();. Here are those two if blocks:

if (myHangman.getAllLettersFound()) {
    JOptionPane.showMessageDialog(null, "You Won!!!!");
    break;
}

if (myHangman.getNumberLives() == 0) {
    JOptionPane.showMessageDialog(null, "You Ran Out Of Guesses");
    break;
}

That should do it. Happy coding!