CODEWITHSUNDEEP
java
user2824852
user2824852

Reputation: 1221

Java scheduling causing an error

This code is supposed to fetch the variables from my class Course.

    public void prettyPrint(){
        Course myCourse = new Course(myCourse.n, myCourse.days, myCourse.start, myCourse.end);


        for (int i=0; i>Courses.size();i++){
            System.out.println("---"+ Course.dayString + ' '+ ' '+" ---");
            System.out.println(myCourse.start +"-"+ myCourse.end+ ": " + myCourse.n );
        }

This gets me errors that say "myCourse.n may not be initalized." How do I initialize them if they are just pulling the info from the Course class?

Upvotes: 0

Views: 45

Answers (2)

amey91
amey91

Reputation: 552

You cannot reference values in an object before creating it. However, you can create static class variables and reference them without creating any objects as shown:

class Course{
    static int n = 1;
    static int days = 180;
    //..other definitions
    //..
}

class Main{
    public static void main(){
      Course myCourse = new Course(Course.n, Course.days);
    }
}

However, static variables introduce dependency between instance variables. A better design would be the factory design pattern with a sample implementation as follows:

class Course{
    int n;
    int days;
    // other instance definitions

    public course(int n, int days){
         this.n = n;
          this.days = days;
     }
}

class History extends Course{
     public History(){
          super(10,200);//the values that you want this course to have
     }
}

class Geography extends Course{
     public Geography(){
          super(20,100);//the values that you want this course to have
     }
}

class Main{
     public static void main(String args[]){
          Course history = new History();
          Course geography = new Geography();
     }
}

Upvotes: 0

enoder
enoder

Reputation: 91

Course myCourse = new Course(myCourse.n, myCourse.days, myCourse.start, myCourse.end); // myCourse is just a reference, when you call new , myCourse hasn't been initialized.

Maybe you should code like this:

Course myCourse = new Course(n, days, start, end);

Upvotes: 1

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