如何使用按钮将 boolean 的值从 false 更改为 true

Question

我为我的 while 循环制作了一个 boolean 以使其在 boolean 等于true时运行，我想让播放按钮使boolean = true触发while循环并运行游戏。 但这由于某种原因不起作用。

有人可以帮助制作boolean gameRunning = true; ? 我只是不知道如何将其值从false更改为true 。

我尝试使用atomic booleans ，但没有奏效

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

您仍在考虑控制台应用程序，Swing 旨在处理事件......

• 用户按下了按钮？ 一个事件
• 一些计时器在后台触发了什么？ 一个事件
• 用户输入了什么？ 一个事件

因此，考虑到上述情况，您不能期望您的代码在这里：

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

while(gameRunning = true) {
    ...
}

要按该顺序执行，因为您无法控制用户何时按下按钮，它可能在 2 秒内，也可能在 2 小时内

为此，您可能需要将while循环移动到一个方法，当用户按下play按钮时，您需要更改gameRunning = true然后调用该其他方法，如下所示：

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();
    }
});

这样，在用户按下play按钮之前，您不会开始游戏。

请注意我刚刚写了没有==的while(gameRunning) ，正如上面的评论中提到的，如果你有gameRunning = true你给它一个值而不是比较它，当使用boolean变量时，你可以简单地这样写，它减少了像这样的错别字的可能性。

• if(true)与if (true == true)相同
• if(!false)与if (false == false)相同
• if(false)与if (true == false)相同

正如我在之前的回答中提到的那样，避免使用null-layout和setBounds ，为什么要实现ActionListener而从不使用它？ 它是空的，所以只需删除implements ActionListener

Answer 2

您不能更改 lambda function 中的局部变量的值。 正如我确信编译器会告诉你的那样，它们需要是最终的或有效的最终，这意味着它们只被分配一次。

解决方案是使用可以容纳您的 Boolean 的类型并更改它所持有的值。

    AtomicBoolean gameRunning = new AtomicBoolean(false);

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

    ...

    while(gameRunning.get()) {
    }