java - 当 JPanel.repaint() 不调用 PaintComponent 时如何修复//我发现没有任何工作

Question

我将创建一个 JPanel Howto，它按顺序渲染 6 个图像，然后添加后退按钮以返回到标题。

我正在尝试检查它是否调用类howto 中的paintComponent 方法。但事实并非如此，所以 i 的值仍然是 0 并且最终陷入循环

这是我的 Howto 类(class)

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;

import javax.swing.JButton;
import javax.swing.JPanel;

import Audio.HitSound;
import Graphic.DrawingUtility;

public class Howto extends JPanel implements Runnable{
    private JButton back;
    private static int i;
    public Howto(){
    this.setPreferredSize(new Dimension(800, 600));
    this.setLayout(null);
    repaint();
    HitSound h = new HitSound();
    i=0;
    this.setVisible(true);
    }

    public void run() {
        // TODO Auto-generated method stub
        try {
            while(i<6)
            {
                GameManager.frame.repaint();
                Thread.sleep(10);
                System.out.println("i: " + i);
            }
        } catch (Exception e) {
            // TODO: handle exception
            Thread.interrupted();
        }
    }
    public void paintComponent(Graphics g){
        if(GameManager.thread.isAlive()){
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.drawImage(DrawingUtility.getHowto(i), 0, 0, 800, 600,null);
            i++;
        }
    }
}

这就是我的 GameManager 类中的内容

public static void startThread() {
        thread = new Thread(howto);
        thread.start();
    }

public static void runHowto() {
    howto = new Howto();
    howto.setVisible(true);
    frame.switchScene(howto);
    howto.repaint();
    startThread();
    while (thread.isAlive()) {
        //frame.repaint();
    }
    if (!thread.isAlive()) {
        JButton back = new JButton();
        back.setBorderPainted(false);
        back.setContentAreaFilled(false);
        back.setFocusPainted(false);
        back.setOpaque(false);
        back.setBounds(640, 446, 132, 132);
        back.addMouseListener(new MouseListener() {

            @Override
            public void mouseReleased(MouseEvent e) {
                // TODO Auto-generated method stub

            }

            @Override
            public void mousePressed(MouseEvent e) {
                // TODO Auto-generated method stub

            }

            @Override
            public void mouseExited(MouseEvent e) {
                // TODO Auto-generated method stub

            }

            @Override
            public void mouseEntered(MouseEvent e) {
                // TODO Auto-generated method stub
                HitSound h = new HitSound();
                h.play(3);
            }

            @Override
            public void mouseClicked(MouseEvent e) {
                // TODO Auto-generated method stub
                GameManager.goToTitle();
            }
        });
    }

但是当我调用 runHowto(); 时它仍然在循环并且 i == 0 并且不增加 i所以我认为paintComponent和repaint方法可能有问题

所以请帮我解决这个问题，提前致谢:)

Answer 1

while (thread.isAlive()) 循环会阻塞 AWT 事件调度线程 (EDT)。

您需要从 runHowto 返回到事件调度循环。让您的 Howto 任务使用 java.awt.EventQueue.invokeLater 发回 EDT，以构造您的后退按钮，并可能将其添加到面板中。