Performing Input and Output - JAVA Programming for Engineers - page 46

A Sample Program
The following Java program demonstrates some of the programming ele-
ments and constructs discussed so far.

On the Web

The source file for the program Area.java can be found in the Chapter
5 directory at www.crcpress.com.

// File name: Area.java

// Reference: Chapter 5

//
// Java program to calculate the area of a circle

// Topics:

// 1. Using numeric variables and constants

// 2. Obtaining keyboard input

// 3. Displaying program data

// 4. Performing simple numeric calculations

//
// Requires:

// 1. Keyin class in the current directory

public class Area
{

// Constant PI is defined at the class level
static final double PI = 3.141592653589793;

public static void main(String[] args)
{

// Local variables
double radius, area;

// Input radius from keyboard
radius = Keyin.inDouble("Enter radius: ");

// Perform calculations and display result
area = PI * (radius * radius);
System.out.println("The area is: " + area);

}

}