在同一包和目录中找不到符号

我有两个课程，提供和课程。它们都位于同一包和同一目录中。

产品.java：

package assignment02;

public class Offering implements Comparable<Offering> {
    private Course course;
    private int CRN;
    private int semester;

    public Offering(Course course, int CRN, int semester) {
        this.course = course;
        this.CRN = CRN;
        this.semester = semester;
    }

    public int getNumCredits() {
        return course.getNumCredits;
    }

    public int getCRN() {
        return CRN;
    }

    public int getSemester() {
        return semester;
    }

    public int compareTo(Offering other) {
        if(other == null) return - 1;
        return semester - other.semester;
    }
}

课程.java：

package assignment02;

public class Course {
    private String name;
    private String rubric;
    private String number;
    private int numCredits;

    public Course(String name, String rubric, String number, int numCredits) {
        this.name = name;
        this.rubric = rubric;
        this.number = number;
        this.numCredits = numCredits;
    }

    public String getName() {
        return name;
    }

    public String getRubric() {
        return rubric;
    }

    public String getNumber() {
        return number;
    }

    public int getNumCredits() {
        return numCredits;
    }
}

当我尝试编译产品时，我收到错误：

D:\CS 140\assignment02>javac Offering.java
Offering.java:4: error: cannot find symbol
    private Course course;
            ^
   symbol:   class Course
   location: class Offering

和

Offering.java:8: error: cannot find symbol
    public Offering(Course course, int CRN, int semester) {
                    ^
   symbol:   class Course
   location: class OfferingOffering.java:8: error: cannot find symbol

我知道这个错误意味着编译器无法对“Course”做任何事情，但我真的不知道为什么。我也知道这最终会变得非常明显，但我似乎无法弄清楚。任何帮助将不胜感激。