Studio: Area of a Circle

Get cosy with Java syntax by revisiting one of our early Python programs. We'll create a console program that calculates the area of a circle based on input from the user.

Creating your class

Since you're still new to Java and IntelliJ, we'll provide some extra direction the first few times we go to write code.

Create a new package named org.launchcode.java.studios by right-clicking on the src directory in java-exercises and selecting New > Package. Be sure to enter the full name, or your package won't be created in the correct location.

Create your program/class in the java-exercises project within the package org.launchcode.java.studios by right-clicking on the studios package/folder and selecting New > Java Class. Enter the name Area.

Your task

Write a program/class Area that prompts the user for a number, and then calculate the area of a circle with that radius and print the result.

Here's an example of how your program should work:

Enter a radius: 2.5
The area of a circle of radius 2.5 is: 19.625

Some questions to ask yourself:

• What data type should the radius be?
• What is the best way to get user input into a variable radius of that type?

Bonus Missions

1. Add validation to your program. If the user enters a negative number, print an error message and quit. You'll need to peek ahead to learn about conditional syntax in Java.
2. Extend your program further by using a while or do-while loop, so that when the user enters a negative number they are re-prompted.