Arrays - Absolute Java - page 366

args? If no argument is given when you run your program, then a default empty array
of strings is automatically provided as a default argument to main when you run your
program.
It is possible to run a Java program in a way that provides an argument to plug in
for this array of String parameters. You do not provide it as an array. You provide any
number of string arguments when you run the program, and those string arguments
will automatically be made elements of the array argument that is plugged in for args
(or whatever name you use for the parameter to main ). This is normally done by
running the program from the command line of the operating system, like so:
java YourProgram Do Be Do
This will set args[0] to "Do" , args[1] to "Be" , args[2] to "Do" , and args.
length to 3 . These three indexed variables can be used in the method main , as in the
following sample program:
public class YourProgram
{
public static void main(String[] args)
{
System.out.println(args[1] + " " + args[0]
+ " " + args[1]);
}
}
If the above program is run from the command line as follows,
java YourProgram Do Be Do
the output produced by the program will be
Be Do Be
Be sure to note that the argument to main is an array of strings . If you want
numbers, you must convert the string representations of the numbers to values of a
number type or types.
The Method main Has an Array Parameter
The heading for the main method of a program is as follows:
public static void main(String[] args)
The identifier args is a parameter for an array of base type String . The details are
explained in the text.