java - 如何停止我的绘画方法表格重复两次？

Question

这是我正在开发的一个骰子游戏的代码，它将结果输出到一个窗口。 paint 方法重复两次，这对我不利，因为我希望骰子掷一次然后继续下一帧。请有人帮我解决这个问题。提前谢谢你。

import java.awt.*;
import java.util.Random;
import javax.swing.*;

public class Dice extends JApplet {

public static int pause(int n)
{
    try {
        Thread.sleep(n);
        } catch(InterruptedException e) {
    }
    return n;
}

public void Dice() {
    JApplet app = new Dice();
    JFrame frame = new JFrame("Dice Game");
    frame.setBounds(30, 50, 1300, 650);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
    frame.add(app);
}

public void paint(Graphics g) {
    int width = getWidth();    
    int height = getHeight(); 

    int num = 0;
    for (int i = 0; i < 7; i++) {
        Random generator= new Random();
        int number = generator.nextInt(6)+1;
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, width, height);
        g.setColor(Color.BLACK);
        g.drawRoundRect(550, 150, 200, 200, 50, 50);
        System.out.println("Test");
        if (number == 1) {              //Roll one
            num = 1;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(640, 240, 20, 20);
            pause(100);
        } if (number == 2) {                //Roll two
            num = 2;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 3) {                //Roll three
            num = 3;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(640, 240, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 4) {                //Roll four
            num = 4;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(590, 190, 20, 20);
            g.fillOval(690, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 5) {                //Roll five
            num = 5;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(590, 190, 20, 20);
            g.fillOval(640, 240, 20, 20);
            g.fillOval(690, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 6) {                //Roll six
            num = 6;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 190, 20, 20);
            g.fillOval(590, 240, 20, 20);
            g.fillOval(590, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            g.fillOval(690, 240, 20, 20);
            g.fillOval(690, 290, 20, 20);
            pause(100);
        }
    }
    g.setFont(new Font("TimesRoman", Font.PLAIN, 20));
    g.drawString("You rolled a " + num, 590, 100);
    pause(1000);
  }
}

Answer 1

• 简短的回答是——你不能。您无法控制 RepaintManager 域中的绘画何时发生。
• 您还应该永远不要在事件调度线程的上下文中调用 Thread.sleep，尤其是不要在任何 paint 方法中
• 您应该避免覆盖 paint 而是使用 paintComponent
• 您应该避免从 JFrame 扩展，而是使用类似 JPanel 的东西，它实际上有一个 paintComponent 方法。
• 这种性质的动画最好通过使用 Swing Timer 来实现，这将允许员工在 EDT 之外保持暂停，但在 EDT 内再次触发使其更安全执行绘画和更新

看看

• Concurrency in Swing
• How to Use Swing Timers
• Performing Custom Painting
• Painting in AWT and Swing

有关绘画如何在 Swing 中工作以及如何实现您正在尝试做的事情的更多详细信息

更新了工作示例

因为我很懒，我使用 Graphics 2D API 来绘制点。我这样做是因为许多点出现在许多数字的相同位置......

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class DiceRoller {

    public static void main(String[] args) {
        new DiceRoller();
    }

    public DiceRoller() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new Die());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class Die extends JPanel {

        private int number = 1;

        public Die() {
            Timer timer = new Timer(500, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    number = (int) (Math.round((Math.random() * 5) + 1));
                    repaint();
                }
            });
            timer.setRepeats(true);
            timer.setInitialDelay(0);
            timer.start();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(220, 220);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int width = getWidth();
            int height = getHeight();

            g2d.setColor(Color.WHITE);
            g2d.fillRect(0, 0, width, height);
            g2d.setColor(Color.BLACK);
            g2d.drawRoundRect(10, 10, width - 20, height - 20, 50, 50);

            List<Shape> dots = new ArrayList<>(6);

            if (number == 1 || number == 3 || number == 5) {
                int x = (width - 20) / 2;
                int y = (height - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
            }

            if (number == 2 || number == 3 || number == 4 || number == 5 || number == 6) {

                int x = ((width / 2) - 20) / 2;
                int y = ((height / 2) - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
                dots.add(new Ellipse2D.Float(x + (width / 2), y + (height / 2), 20, 20));

            }

            if (number == 4 || number == 5 || number == 6) {

                int x = (width / 2) + (((width / 2) - 20) / 2);
                int y = ((height / 2) - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
                dots.add(new Ellipse2D.Float(x - (width / 2), y + (height / 2), 20, 20));

            }

            if (number == 6) {

                int x = (((width / 2) - 20) / 2);
                int y = (height - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
                dots.add(new Ellipse2D.Float(x + (width / 2), y, 20, 20));

            }

            for (Shape dot : dots) {
                g2d.fill(dot);
            }

            g2d.dispose();
        }
    }
}