java - 如何在 JFrame 窗口中实时显示多个图像？

Question

出于我项目的目的，我试图通过使用给定的公式实时创建多个圆圈来模拟叶序模式。

所以最近，我决定尝试使用 JFrame 和 swing 在 Java 中进行 GUI 编程，但我在试图弄清楚如何让一切正常运行时遇到了困难。我的想法是慢慢地打印出一个又一个圆圈，它们的 x 和 y 坐标是根据叶序指令中记录的“r = cos/sin(theta)”公式计算的。不幸的是，虽然 x 和 y 值不断变化，但只打印了一个圆圈。有什么我想念的吗？

package gExample;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.Timer;


public class GraphicsExample extends Canvas implements ActionListener {

private final static int HEIGHT = 600; 
private final static int WIDTH = 600; 
private int n = 0;
private int x, y;
Timer t = new Timer(20, this);

public static void main(String args[]) {
    JFrame frame = new JFrame();
    GraphicsExample canvas = new GraphicsExample();

    canvas.setSize(WIDTH, HEIGHT);
    frame.add(canvas);
    frame.pack();
    frame.setVisible(true);
    frame.setResizable(false);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    canvas.setBackground(Color.black);
}

public void paint(Graphics g){ 
    Random rand = new Random();

    Color col = new Color(rand.nextInt(256), rand.nextInt(256), rand.nextInt(256));
    g.setColor(col);

       /*each time paint() is called, I expect a new circle to be printed in the
        x and y position that was updated by actionPerformed(), but only one inital circle is created. */
    g.fillOval(x, y, 8, 8);

    t.start();

}


@Override
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub

    int c = 9;
    double r = c * Math.sqrt(n);
    double angle = n * 137.5;

    //here, every time the method is called, the x and y values are updated, 
   //which will be used to fill in a new circle
    int x = (int) (r * Math.cos(angle * (Math.PI / 180) )) + (WIDTH / 2);
    int y = (int) (r * Math.sin(angle * (Math.PI / 180) )) + (HEIGHT / 2);

    //when the program is running, this line of code is executed multiple times.
    System.out.println("x: " + x + " y: " + y);

    n++;

}




}

标签： javaswingjframe