java相邻包不存在

Question

我在Four\ Seasons\ Lab/things/Mountain.java中有一个public class Mountain，并尝试使用import shapes.Triangle导入public class Triangle中的类public class Triangle（注意：import shapes.*也不起作用）。出于某种原因，每当我尝试使用Triangle类时，它总是抛出package shapes does not exist，以及cannot find symbol。我该如何解决这个问题

山。java

package things;

import shapes.Triangle;

import java.awt.Graphics;
import java.awt.Color;

public class Mountain {
    private Triangle body;

    public Mountain(int x, int y, int dx, int dy) {
        this.body = new Triangle(
            x, y + dy,
            x + dx/2, y,
            x + dx, y + dy
        );
    }

    public void draw(Graphics g) {
        body.draw(g);
    }
}

三角形。java

package shapes;

import java.awt.Graphics;
import java.awt.Color;

public class Triangle {
    private Color color;
    private int[] pointA;
    private int[] pointB;
    private int[] pointC;
    
    public Triangle(Color color, int aX, int aY, int bX, int bY, int cX, int cY) {
        this.color = color;
        this.pointA = new int[] {aX, aY};
        this.pointB = new int[] {bX, bY};
        this.pointC = new int[] {cX, cY};
    }
    // more code
}

File Tree

Screenshot of Mountain.java

注:

1. Runner将运行Scenery，这将运行Mountain
2. 程序必须通过以下方式在终端中运行：

(in "Four Seasons Lab" directory)
$ javac *.java
$ java Runner

（通过仅包含.java文件的.zip文件共享）