为什么不画正方形？

Question

我开始了一个国际象棋项目，重用一些旧代码来绘制地图，基本上所有内容都已复制粘贴。问题是方块不显示？我现在尝试修复它一段时间，但没有解决方案。这可能是三个最重要的方法和整个项目的 zip。其中一些是德语。

https://drive.google.com/file/d/1nnZHLB0Ycy04eMyYbEmduMwbGhVLZ2VB/view?usp=sharing

public SchachFrame() {
        super();
        contentPane = new JPanel();
        setContentPane(contentPane);
        setBounds(0, 0, window.width, window.height);
        contentPane.setBackground(Color.darkGray);
        contentPane.setVisible(true);
        
        ge = new GameEnvironment(this);
        ge.setBounds(window.width/2 - 500, window.height/2 - 500, 1000, 1000);
        ge.setVisible(true);
        contentPane.add(ge);
        
        Thread gameEnvironment = new Thread(ge);
        gameEnvironment.start();
        
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    } 


public void createMap(int width, int length, GameEnvironment ge) {
        map = new Spielfeld[length][width];
        Spielfeld.width = 1000/width;
        Spielfeld.height = 1000/length;
        for(int i = 0; i < length; i++) {
            for(int j = 0; j < width; j++) {
                this.map[i][j] = new Spielfeld(j, i, null);
                this.map[i][j].setBounds(ge.getX() + j * Spielfeld.width, ge.getY() + i * Spielfeld.height, Spielfeld.width, Spielfeld.height);
                this.map[i][j].setVisible(true);
                ge.add(this.map[i][j]);
            }
        }
    }


public void paintComponent(Graphics g) {
        if((this.px + this.py) % 2 == 0) {
            g.setColor(Color.blue);
        } else {
            g.setColor(Color.cyan);
        }
        g.fillRect(this.getX(), this.getY(), this.getWidth(), this.getHeight());
        repaint();
    }

Answer 1

不要在paintComponent 中调用repaint()。否则，您将永远不会退出 EDT 并锁定您的代码。而paintComponent(Graphics g)中的第一条语句应该是super.paintComponent(g);

更新以包含一个示例

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class DrawSquareComponent extends JPanel {
    static int WIDTH = 600;
    static int HEIGHT = 600;
    JFrame frame = new JFrame();
    
    public static void main(String[] args) {
        new DrawSquareComponent().start();
    }
    
    public void start() {
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(this);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        setBackground(Color.white);
        MyComponent my =new MyComponent();
        add(my); // add my component to panel
        Random r = new Random();
        for (int i = 0; i < 20; i++) {
            int size = r.nextInt(50)+50;
            int x = r.nextInt(WIDTH-size)+1;
            int y = r.nextInt(HEIGHT-size)+1;
            my.setBounds(x,y,size,size);
            frame.repaint();
            try {
                Thread.sleep(1000);
            } catch (InterruptedException ie) {
            }
        }
    }
    
    public Dimension getPreferredSize() {
        return new Dimension(WIDTH, HEIGHT);
    }
}

class MyComponent extends JPanel {
    @Override
    public void paintComponent(Graphics g) {
        Graphics gg = g.create();
        super.paintComponent(gg);
        // location relative to parent's.
        // used to check location in parent's coordinate space.
        Point p = getLocation();
        if ((p.x + p.y) % 2 == 0) {
            gg.setColor(Color.blue);
        } else {
            gg.setColor(Color.cyan);
        }
        // paint this component so location is always 0,0.
        // all you're doing is painting this squares background
        gg.fillRect(0,0, this.getWidth(), this.getHeight());
        gg.dispose();
    }
}