(Diameter, Circumference and Area of a Circle) Here's a peek ahead. In this
chapter, you learned about integers and the type int. Java can also represent
floating-point numbers that contain decimal points, such as \(3.14159 .\) Write
an application that inputs from the user the radius of a circle as an integer
and prints the circle's diameter, circumference and area using the floating-
point value 3.14159 for \(\pi .\) Use the techniques shown in Fig. 2.7. \([\)Note:
You may also use the predefined constant Math.PI for the value of \(\pi\). This
constant is more precise than the value \(3.14159 .\) Class Math is defined in
package java. lang. Classes in that package are imported automatically, so you
do not need to import class Math to use it.] Use the following formulas ( \(r\)
is the radius):
diameter \(=2 r\) circumference \(=2 \pi r\) area \(=\pi r^{2}\)
Do not store the results of each calculation in a variable. Rather, specify
cach calculation as the value that will be output in a System.out.printf
statement. The values produced by the circumference and area calculations are
floating-point numbers. Such values can be output with the format specifier
\(\% \mathrm{f}\) in a System.out.printf statement. You'll learn more about
floating-point numbers in Chapter 3.