Java画布按键选择圆形个数个数画出圆形

以下是一个简单的 Java 代码示例，用于创建一个画布，并允许用户通过按键选择要绘制的圆的数量：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class CircleDrawer extends JFrame implements KeyListener {
    private static final int WIDTH = 500;
    private static final int HEIGHT = 500;
    private int numCircles = 1;

    public CircleDrawer() {
        setSize(WIDTH, HEIGHT);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        addKeyListener(this);
    }

    public void paint(Graphics g) {
        super.paint(g);
        int centerX = WIDTH / 2;
        int centerY = HEIGHT / 2;
        int radius = 50;

        for (int i = 0; i < numCircles; i++) {
            g.drawOval(centerX - radius, centerY - radius, radius * 2, radius * 2);
            radius += 50;
        }
    }

    public static void main(String[] args) {
        CircleDrawer circleDrawer = new CircleDrawer();
        circleDrawer.setVisible(true);
    }

    @Override
    public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_UP) {
            numCircles++;
            repaint();
        } else if (e.getKeyCode() == KeyEvent.VK_DOWN) {
            if (numCircles > 1) {
                numCircles--;
                repaint();
            }
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        // Do nothing
    }

    @Override
    public void keyTyped(KeyEvent e) {
        // Do nothing
    }
}

该程序创建了一个 JFrame，其中包含一个画布和一个 numCircles 变量，该变量表示要绘制的圆的数量。使用上下箭头键可以增加或减少圆的数量，并通过 paint() 方法在画布上绘制圆。