title: Using a constructor in Java
body: <p>Question #3 for the day. I've got to design a program that can read in a specific Radius from a user, then display A/D/C of the relevant circle. I've written up the constructor I need to do this, but I seem to have gotten confused on what I'm supposed to do with it.</p>
  
  <p>How do I take what I've got in the constructor and use it in main?</p>
  
  <p>Relevant constructor code:</p>
  
  <pre><code>public class GetCircle {
  private float radius;
  private double diameter,circumference,area;
  
  public GetCircle(float getRadius, double setDiameter, double setCircumference, double setArea){
      radius=getRadius;
      diameter=setDiameter;
      circumference=setCircumference;     
      area=setArea;
  }
  public void setRadius(float getRadius){
      radius=getRadius;
  }
  public float getRadius(){
      return radius;
  }   
  public void setDiameter(double setDiameter){
      diameter=setDiameter;
  }
  public double setDiameter(){
      return diameter;
  }
  public void setCircumference(double setCircumference){
      circumference=setCircumference;
  }       
  public double setCircumference(){
      return circumference;
  }
  public void setArea(double setArea){
      area=setArea;
  }
  public double setArea(){
      return area;
  }
  public void answer(){
      System.out.println("The Radius that you specified was: " + getRadius());
      System.out.println("The Diameter of your circle is: " + setDiameter());
      System.out.println("The Circumference of your circle is: " + setCircumference());
      System.out.println("The Area of your circle is: " + setArea());
      }
  </code></pre>
  
  <p>}</p>
  
  <p>Relevant Main method:</p>
  
  <pre><code>import java.util.Scanner;
  public class Circle {
  
  public static void main (String[] args){
      double PI = 3.14159;
      Scanner input = new Scanner(System.in);
      System.out.println("Hello, for this exercise we require that you input the Radius of the circle of your choosing: ");
  
  
  }
  
  }
  </code></pre>
  
  <p>I've really got two questions I suppose:
  1) How to I take what I've got from my constructor class and bring it into my main method.
  2) Where is the best place to define the "math" for the circle (IE 2πr etc). </p>
  
  <p>Thanks!</p>