Finding the radius, diameter, area and circumference of a circle

Question

So I'm still new to programming and I don't know if this is all correct or not, but I'm trying to find the area circumference of a circle with a given radius.

So far I have this:

public class Circle  {

   private double radius;

   public Circle(double r) {

   }

   public double getRadius()  {
      return radius;
   }

   public void setRadius(double r)  {
   }

   public double diameter()  {
      double diameter = radius * radius;
      return diameter;
   }

   public double area()   {
      double area = Math.PI * (radius * radius);
      return area;
   }

   public double circumference()   {
      double circumference = 2 * Math.PI * radius;
      return circumference;
   }
}

I also have this other part too...

public class CircleTest {
   private static void circleTest (int r) {
      Circle circleTest = new Circle(-2);
      System.out.printf("Parameter: %d%n", r);
      System.out.printf("Radius: %.1f %n", circleTest.getRadius());
      System.out.printf("Diameter: %.1f %n", circleTest.diameter());
      System.out.printf("Area: %.1f %n", circleTest.area());
      System.out.printf("Circumference: %.1f %n", circleTest.circumference());
   }

   public static void main(String[] args) {

   }
}

I don't know if this is right or not, but it compiles just fine but it doesn't print anything out when I run it. What am I doing wrong???

Why are you passing a negative radius and why is your constructor blank inside? How do you think radius gets a value in your program? — Ravi K Thapliyal, Feb 24 '15 at 05:28
Your `main` method is empty, which means it will do nothing. — ntalbs, Feb 24 '15 at 05:29
You have diameter as r^2 ... Programming doesn't matter if you don't know math. — ghostbust555, Feb 24 '15 at 05:30

SabaRish · Accepted Answer · 2015-02-24T05:38:33.443

the code has few mistakes . it has to be like this

public class Circle  {

   private double radius;

   public Circle(double r) {
    radius = r;

   }

   public double getRadius()  {
      return radius;
   }

   public void setRadius(double r)  {
   }

   public double diameter()  {
      double diameter = radius * radius;
      return diameter;
   }

   public double area()   {
      double area = Math.PI * (radius * radius);
      return area;
   }

   public double circumference()   {
      double circumference = 2 * Math.PI * radius;
      return circumference;
   }
}

main class has to be like this

public class CircleTest {
      public static void main(String[] args) {
         Circle circleTest = new Circle(-2);
              System.out.printf("Parameter: %d%n", r);
              System.out.printf("Radius: %.1f %n", circleTest.getRadius());
               System.out.printf("Diameter: %.1f %n", circleTest.diameter());
              System.out.printf("Area: %.1f %n", circleTest.area());
              System.out.printf("Circumference: %.1f %n", circleTest.circumference());
           }
        }

mistakes you have made 1) your code has to be in main method .2) the constructor parameter has to be set to the class variable.

score -1 · Answer 2 · answered Feb 24 '15 at 05:29

-1

In the Java language, when you execute a class with the Java interpreter, the runtime system starts by calling the class's main() method.

The Java Main Method

You should put some code in this block

   public static void main(String[] args) {

   }

answered Feb 24 '15 at 05:29

bumbumpaw

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Finding the radius, diameter, area and circumference of a circle

2 Answers2