Using Command-Line Arguments

Using Command-Line Arguments:

Sometimes you will want to pass information into a program when you run it. This is accomplished by passing command-line arguments to main( ). A command-line argument is the information that directly follows the program's name on the command line when it is executed. To access the command-line arguments inside a Java program is quite easy—they are stored as strings in the String array passed to main( ).

 

For example, the following program displays all of the command-line arguments that it is called with:

 

// Display all command-line arguments.

class CommandLine {

public static void main(String args[]) {

for(int i=0; i<args.length; i++)

System.out.println("args[" + i + "]: " +

args[i]);

}

}

 

Try executing this program, as shown here:

 

java CommandLine this is a test 100 -1

 

When you do, you will see the following output:

args[0]: this

args[1]: is

args[2]: a

args[3]: test

args[4]: 100

args[5]: -1

 

All command-line arguments are passed as strings. You must convert numeric values to their internal forms manually.