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

可以使用以下代码实现：

import edu.princeton.cs.introcs.StdDraw;

public class Turtle {
    private double x, y; // turtle position
    private double angle; // turtle angle

    // constructor
    public Turtle(double x0, double y0, double a0) {
        x = x0;
        y = y0;
        angle = a0;
    }

    // rotate the turtle's angle by delta degrees clockwise
    public void turn(double delta) {
        angle += delta;
    }

    // move the turtle forward a given distance
    public void goForward(double distance) {
        double oldx = x;
        double oldy = y;
        x += distance * Math.cos(Math.toRadians(angle));
        y += distance * Math.sin(Math.toRadians(angle));
        StdDraw.line(oldx, oldy, x, y);
    }

    // move the turtle backward a given distance
    public void goBackward(double distance) {
        goForward(-distance);
    }

    // set the turtle's position to (x, y)
    public void setPosition(double x, double y) {
        this.x = x;
        this.y = y;
    }

    // set the turtle's angle to a
    public void setAngle(double a) {
        angle = a;
    }
}

这个类中包含了最基本的海龟绘图 API：前进、后退、左转、右转、设置位置和方向。在 `setPosition` 方法中，只需要简单地将 `x` 和 `y` 的值设为相应的参数即可。