Hi everyone, I am brand new to Java and I like it a lot so far. I am very stuck on an assignment for school that I need help with. We are just learning about method invocation, how to write and call methods in Java. My program should take user generated input for a radius value and output the volume, area, and radius of a sphere in a dialoge box. The Output/Input classes are just classes my professor wrote to allow us a pretty interface (we haven't used sys.out.println yet). I cannot get my method invocation to work. The compilation window tells me the the variables in my method invocation are not yet declared. I am stuck. Help would be so appreciated! thanks

Here is what I've got:

    public class Sphere
        public static void sphereOut(double rad, double volume, double a)

            String menu = "Your radius is: " +rad+ "\n";
            menu = menu + "Your volume is: " +volume+ "\n";
            menu = menu + "Your area is: " +a; 

        }//method sphereOut

        public static double area (double rad)

            double a;   
            a = 4.0 * 3.14 * rad * rad;
            return a;

        }//method area

        public static double volume (double volume)

        double volume
        4.0/3.0 * 3.14 * rad * rad * rad;
        return volume;

        }//method volume

        public static double getRadius ()

            double rad; 
            rad = Input.readDouble("Enter a positive radius");
            while (rad < 0)
                rad = Input.readDouble("Error enter a positive value");     
            Output.showValue("The radius you entered is: ", rad);
            return rad;

        }//method getRadius     

        public static void main(String [] args)

            Sphere.sphereOut(rad, volume, a);

        }//method main
    }//class Sphere 
5 Years
Discussion Span
Last Post by Taywin

I'm not sure what you are talking about, but my guess is that stuff like this


is where your code crashes. Unless you have a class Output with static methods (along which showMessage(..)) this will cause compile time errors..

my suggestion, for as far as I can see your code, replace the above by:


the same kind of addaptations for the other methods.


No, I think lines 48~50 are causing the problem (in main()). The reason is that all of those variable being passed to methods are not declare/initialised anywhere inside the main(). I believe the professor asks the OP to enter a real number, not a variable.

// i.e.

But then all variable name and the method definition are all wrong though... So not sure what the OP really needs to do.

Edited by Taywin


so, Taywin: do you know of an output class with a static showMessage method that can be used without an import? I can't even think of one in the basic api's.


No I don't know what it is. However, the OP said the display is taken from the professor. Therefore, I would assume that it would be as simple as leaving the class in the same directory/folder as the OP class. That way, the program does not need to call import if the program is not being in a package.

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