Defining Classes - Beginning Java - page 223

class CreateSpheres {
public static void main(String[] args) {
System.out.println("Number of objects = " + Sphere.getCount());

Sphere ball = new Sphere(4.0, 0.0, 0.0, 0.0); // Create a

sphere
System.out.println("Number of objects = " + ball.getCount());

Sphere globe = new Sphere(12.0, 1.0, 1.0, 1.0); // Create a

sphere
System.out.println("Number of objects = " + Sphere.getCount());

// Output the volume of each sphere
System.out.println("ball volume = " + ball.volume());
System.out.println("globe volume = " + globe.volume());

}

Directory "Create Spheres"

This file should be in the same directory as the file containing the Sphere class definition. Compile the
source files and then run CreateSpheres , and you should get the following output:
Number of objects = 0
Number of objects = 1
Number of objects = 2
ball volume = 267.94666666666666
globe volume = 7234.559999999999

This is the first time you have run a program involving two source files. If you are using the JDK com-
piler, then compile CreateSpheres.java with the current directory as Create Spheres using the com-
mand
javac CreateSpheres.java

The compiler finds and compiles the Sphere.java source file automatically. If all the source files for a
program are in the current directory then compiling the file containing a definition of main() compiles
all the source files for the program.
Note that by default the .class files generated by the compiler are stored in the current directory — that
is, the directory containing your source code. If you want the .class files stored in a different directory
then you can use the -d option with the Java compiler to specify where they should go. For example, to
store the class files in a directory called C:\classes , you type:
javac -d C:/classes CreateSpheres.java

How It Works