Question

Im learning java and I have problem with get and set methods in other classes.

My first class is named Department and second is named Company. I would like to set number of staff in class Department and get number of staff in class Company.

Department class

public class Department {

    public int staffNumber;

    public Department() {
    }

    public void setStaffNumber(int staff) {
        this.staffNumber= staff;
    }

}

Company class

public class Company {

     public Department staffNumber;

     public Company() {
     }

     public Department getStaffNumber() {
          return Department.staffNumber = Department.staffNumber;
     }

}

Can you please help me with error message – non-static variable staffNumber cannot be referenced from a static context ?
Thank you

Answer 1

The problem is here:

return Department.staffNumber = Department.staffNumber;

The compiler will read Department.staffNumber as: staffNumber is a static variable in the Department class. There your problem.

In order to solve this, you should just return the instance data:

public Department getStaffNumber() {
    //<Department attribute in the class>
    return staffNumber;
}

By the way,even if you have a Department.staffNumber static attribute inside the Department class, the proposed line return Department.staffNumber = Department.staffNumber; won’t make any sense. It’s similar to this:

public class SomeClass {

    int x;

    public int getX() {
        //return x = x; //clumsy
        return x; //now this might be better
    }
}