how to use math.pi in java

Question

I am having problems converting this formula V = 4/3 π r^3. I used Math.PI and Math.pow, but I get this error:

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Answer 1

Replace

volume = (4 / 3) Math.PI * Math.pow(radius, 3);

With:

volume = (4 * Math.PI * Math.pow(radius, 3)) / 3;

Answer 2

You're missing the multiplication operator. Also, you want to do 4/3 in floating point, not integer math.

volume = (4.0 / 3) * Math.PI * Math.pow(radius, 3);
           ^^      ^

Answer 3

Here is usage of Math.PI to find circumference of circle and Area First we take Radius as a string in Message Box and convert it into integer

public class circle {

    public static void main(String[] args) {
        // TODO code application logic here

        String rad;

        float radius,area,circum;

       rad = JOptionPane.showInputDialog("Enter the Radius of circle:");

        radius = Integer.parseInt(rad);
        area = (float) (Math.PI*radius*radius);
        circum = (float) (2*Math.PI*radius);

        JOptionPane.showMessageDialog(null, "Area: " + area,"AREA",JOptionPane.INFORMATION_MESSAGE);
        JOptionPane.showMessageDialog(null, "circumference: " + circum, "Circumfernce",JOptionPane.INFORMATION_MESSAGE);
    }

}

Answer 4

Your diameter variable won't work because you're trying to store a String into a variable that will only accept a double. In order for it to work you will need to parse it

Ex:

diameter = Double.parseDouble(JOptionPane.showInputDialog("enter the diameter of a sphere.");