java使用StdDraw创建一个Turtle实现 Turtle Graphics API中setPenColor的功能

你好！关于你的问题，可以使用以下代码实现：

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.geom.Line2D;

import javax.swing.JFrame;

public class Turtle {

    private static double x;
    private static double y;
    private static double angle;
    private static JFrame frame;

    public static void main(String[] args) {
        frame = new JFrame();
        frame.setSize(500, 500);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        setPenColor(Color.RED);
        penDown();
        forward(100);
        turnLeft(90);
        forward(100);
        turnLeft(90);
        forward(100);
        turnLeft(90);
        forward(100);
        frame.dispose();
    }

    public static void setPenColor(Color color) {
        Graphics2D g = (Graphics2D) frame.getContentPane().getGraphics();
        g.setPaint(color);
    }

    public static void penDown() {
        x = 250;
        y = 250;
    }

    public static void forward(double distance) {
        double newX = x + distance * Math.cos(angle * Math.PI / 180);
        double newY = y - distance * Math.sin(angle * Math.PI / 180);
        Graphics2D g = (Graphics2D) frame.getContentPane().getGraphics();
        Line2D line = new Line2D.Double(x, y, newX, newY);
        g.draw(line);
        x = newX;
        y = newY;

    }

    public static void turnLeft(double turnAngle) {
        angle += turnAngle;
    }

}

这是一个简单的 Turtle Graphics API 实现，并且可以使用 setPenColor 方法设置画笔的颜色。具体的实现方式是使用 Graphics2D 类的 setPaint 方法。希望能够帮到你！