Help with Circle Class :)

[Mike Pirrone]

Ok, I am in a beginning java class and cannot figure out this problem. The purpose of this program is to call upon a class (Circle) and compute the radius and area of the circle. when i compile though, i get this following error:
A:\TestCircle.java:12: Incompatible type for method. Can't convert void to char[].
System.out.print(circle1.computeDiameter());
Here is my source code:
For my Circle Class

public class Circle
{
    private int Radius;
    private double Area;
    private double Diameter;
    Circle()
{
Radius = 1;
    }
public int getRadius()
{
return Radius;
}
public void setRadius(int n)
{
Radius = n;
}
public void computeDiameter()
{
Diameter = 2*Radius;
}
public void computeArea()
    {
Area = 3.14*(Radius*Radius);
}
}
And now for my TestCircle Class
   public class TestCircle
{
   public static void main(String[] args)
   {
Circle circle1 = new Circle();
circle1.setRadius(5);
System.out.print("The Diameter of the Circle      is ");
System.out.println(circle1.computeDiameter());
}
}

I really appreciate any form of help. Thank you so much!
-mike-
(edited to format the code - Dave)
[This message has been edited by Dave Vick (edited October 30, 2001).]

[Peter Chase]

You try to print the result of computeDiameter(), but that method has a void return - it stores the result in the member variable.
Instead, you need to call computeDiameter(), then separately print the member variable. Either that, or change the computeDiameter() method to return the diameter it has computed.

[Dave Vick]

Mike
The short answer for your error:
You're calling the method computeDiameter() in the println method. Your computeDiameter() method returns void and println can't print void.
The long answer:
In your circle class you have the area and diameter variables set as private but you have no accessor methods to get at the values once they've been set with computeArea or computeDiameter. You could just have methods called getDiameter and getArea that do the calculation each time and return a float as an answer. Then all you'd have to do is store the radius as a variable and the various get methods would calculate their answers when they are called. If you store the values for diameter and area then you'll have to recalculate them each time the radius changes.
hope that helped, it was probably more of answer than you were looking for

------------------
Dave
Sun Certified Programmer for the Java� 2 Platform

[Ryan Perlman]

Hello I am just another student who has done a similar problem
Here is the web page to the source:
http://ryanperlman.tripod.com/school/your_circle.htm
hope that helps

[Mike Pirrone]

Thank you so much guys. your url did not work though at the bottom. but its cool. much thanks

[Ryan Perlman]

http://ryanperlman.tripod.com/school/yourcircle_source.htm
Here's that url again sorry for the last one not being correct
http://ryanperlman.tripod.com/schoo/java.htm