Java Get and Set returning value 0 on an operation

Question

I'm having trouble getting the value of an operation. All I get as a result is 0. I've tried many things but nothing seems to work. I'm a beginner so I'm sorry if this is something really simple. I looked around for similar problems but I couldn't seem to find one that matched my issue

public class Circle {
    double rad, C, D, A, A2, V;

    public double getRad(){
        return rad;
    }

    void setRad(double valueRad){
        this.rad = valueRad;
    }

    public double getCircumference(){
        return C;
    }

    void setCircumference(double Circ){
        Circ = (rad*2)*(Math.PI);
        this.C = Circ;
    }
}

And this is my main:

public class Main {
    public static void main(String[] args) {

        Circle res = new Circle();

        res.setRad(5.80);

        System.out.println("The circumference is: "+res.getCircumference()+" cm");
    }
}

Answer 1

Your calculation code is in the setCircumference() method which is never called. When you call the getCircumference() method the default C field value of 0.0 is returned.

One way to fix it would be to calculate the value in the getCircumference() method:

public class Circle {
  private double rad;

  public void setRad(double rad) {
    this.rad = rad;
  }

  public double getCircumference() {
    return rad * 2 * Math.PI;
  }
}