How to change the value of a boolean from false to true using a button

Question

I made a boolean for my while loop to make it run when the boolean is equal to true, I wanted to make the play button make the boolean = true which would trigger the while loop and run the game. But this isn't working for some reason.

Can someone help with making the boolean gameRunning = true;? I just can't figure out how to change its value from false to true.

I tried using atomic booleans but that didn't work

package panda.org;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.lang.Math;
import java.util.concurrent.atomic.AtomicBoolean;

public class NumberGame implements ActionListener{

    JFrame frame;
    JLabel rules;
    JLabel rulesText;
    JLabel rulesText2;
    JButton play;
    JButton exit;

    Font myFont = new Font("Serif Plain", Font.BOLD, 15);

    NumberGame() {

        frame = new JFrame("NumberGame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(600, 500);
        frame.setLocationRelativeTo(null);
        frame.setLayout(null);
        frame.setResizable(true);
        Image icon = Toolkit.getDefaultToolkit().getImage("C:\\Users\\Gaming MSI\\Pictures\\Saved Pictures\\download (1).png");
        frame.setIconImage(icon);

        rules = new JLabel("Rules: ");
        rules.setFont(myFont);
        rules.setBounds(50, 100, 100, 75);

        rulesText = new JLabel("We will pick a random number in the range of 1 -> 50.");
        rulesText.setBounds(100, 100, 315, 75);

        rulesText2 = new JLabel("Your job is to guess that number!");
        rulesText2.setBounds(100, 120, 315, 75);

        play = new JButton("Play");
        play.setBounds(150, 300, 100, 75);

        boolean gameRunning = false;

        play.addActionListener(e -> {
            gameRunning = true;
        });

        while(gameRunning = true) {

            JLabel label = new JLabel("Guess the number from 1 till 50");
            label.setFont(myFont);
            label.setBounds(150, 75, 315, 75);

            JLabel hints = new JLabel("");
            hints.setBounds(150, 180, 1000, 100);

            JLabel hints2 = new JLabel("");
            hints2.setBounds(150, 200, 1000, 100);

            JTextField text = new JTextField();
            text.setBounds(250, 150, 100, 25);

            JButton check = new JButton("Check");
            check.setBounds(150, 150, 75, 25);

            double randomDouble = Math.random();
            randomDouble = randomDouble * 50 + 1;

            double randomDouble2 = Math.random();
            randomDouble2 = randomDouble2 * (15 - 5 + 1) + 5 ;

            double randomDouble3 = Math.random();
            randomDouble3 = randomDouble3 * (15 - 5 + 1) + 5 ;

            int randomHint = (int) randomDouble2;
            int randomHint2 = (int) randomDouble3;
            int randomInt = (int) randomDouble;

            System.out.println("nb: " + randomInt);
            System.out.println("hint: " + randomHint);
            System.out.println("hint2: " + randomHint2);

            JLabel status = new JLabel("");
            status.setBounds(150, 160, 1000, 100);

            JLabel closeness = new JLabel("");
            closeness.setBounds(150, 220, 1000, 100);
            closeness.setForeground(Color.blue);

            final int[] failedAttempts = {0};

            check.addActionListener(e1 -> {

                String nb = text.getText();
                int change = Integer.parseInt(nb);

                frame.add(status);

                if (randomInt == change) {
                    status.setText("You chose the correct number!");
                    status.setForeground(Color.green);

                    hints.setText("");
                    hints2.setText("");
                }
                if (randomInt > change) {

                    closeness.setText("Your answer is smaller than the correct answer");

                }
                if (randomInt < change) {

                    closeness.setText("Your answer is larger than the correct answer");

                }
                if (randomInt != change) {
                    status.setText("Wrong choice! Try again.");
                    status.setForeground(Color.red);
                    failedAttempts[0]++;

                    if (failedAttempts[0] == 3) {

                        int plus = randomInt + randomHint;
                        int minus = randomInt - randomHint2;

                        hints.setText("Hint: I see you are struggling, here is a low range to make it easier!");
                        hints2.setText("The lowered range is from " + plus + " to " + minus);
                    }
                }
            });

            rules.setText("");
            rulesText.setText("");
            rulesText2.setText("");

            frame.add(hints);
            frame.add(hints2);
            frame.add(label);
            frame.add(check);
            frame.add(closeness);
            frame.add(text);
        }

        exit = new JButton("Exit");
        exit.setBounds(350, 300, 100, 75);
        exit.addActionListener(e -> {

            int result = JOptionPane.showConfirmDialog(frame,"Are you sure want to exit?", "Exit",
                    JOptionPane.YES_NO_OPTION,
                    JOptionPane.QUESTION_MESSAGE);
            if(result == JOptionPane.YES_OPTION){
                System.exit(0);
                }
        });

        frame.add(play);
        frame.add(exit);
        frame.add(rules);
        frame.add(rulesText);
        frame.add(rulesText2);

        frame.setVisible(true);
    }

    public static void main(String[] args) {

        NumberGame number = new NumberGame();

    }

    @Override
    public void actionPerformed(ActionEvent e) {

    }
}

Answer 1

You're still thinking in console applications, Swing is designed to work with events...

• The user pressed a button? An event
• Some timer triggered something in the background? An event
• User typed something? An event

So, with the above in mind, you cannot expect your code here:

play.addActionListener(e -> {
    gameRunning = true;
});

while(gameRunning = true) {
    ...
}

To be executed in that order, because you have no control of when the user is going to press the button, it could be either in 2 seconds, or could be in 2 hours

For this to happen, you might need to move the while loop to a method, and when the user presses the play button, you need to change gameRunning = true and then call that other method, something like this:

public void runGame() {
    while(gameRunning) {
        // Your code here
    }
}

play.addActionListener(e -> {
    if (!gameRunning) { //This validation is needed otherwise if you press the button multiple times you'll have multiple loops running
        gameRunning = true;
        runGame();
    }
});

This way, you don't start your game until the user presses the play button.

Notice how I just wrote while(gameRunning) without ==, as mentioned in the comments above, if you have gameRunning = true you're assigning it a value instead of comparing it, when using boolean variables you can simply write them like that, it reduces the possibility of typos like that one.

• if(true) is the same as if (true == true)
• if(!false) is the same as if (false == false)
• if(false) is the same as if (true == false)

And as I mentioned in my previous answer avoid the use of null-layout and setBounds and why are you implementing ActionListener and never using it? It's empty, so just remove implements ActionListener

Answer 2

You can not change the value of a local variable in a lambda function. As I am sure the compiler is telling you, they need to be final or effectively final which means they are only assigned once.

The solution is to use a type that can hold your Boolean and change the value that it is holding instead.

    AtomicBoolean gameRunning = new AtomicBoolean(false);

    play.addActionListener(e -> {
        gameRunning.set(true);
    });

    ...

    while(gameRunning.get()) {
    }