Ex.java

Below is the syntax highlighted version of Ex.java from §1.3 Conditionals and Loops.

/******************************************************************************
 *  Compilation:  javac Ex.java
 *  Execution:    java Ex n
 *
 *  Prints out an X of radius n like the one below.
 *
 *  % java Ex 3
 *  * . . . . . *
 *  . * . . . * .
 *  . . * . * . .
 *  . . . * . . .
 *  . . * . * . .
 *  . * . . . * .
 *  * . . . . . *
 *
 *  % java Ex 5
 *  * . . . . . . . . . *
 *  . * . . . . . . . * .
 *  . . * . . . . . * . .
 *  . . . * . . . * . . .
 *  . . . . * . * . . . .
 *  . . . . . * . . . . .
 *  . . . . * . * . . . .
 *  . . . * . . . * . . .
 *  . . * . . . . . * . .
 *  . * . . . . . . . * .
 *  * . . . . . . . . . *
 *
 ******************************************************************************/

public class Ex {

    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]);

        for (int i = -n; i <= n; i++) {
            for (int j = -n; j <= n; j++) {
                if ((i == -j) || (i == j)) System.out.print("* ");
                else                       System.out.print(". ");
            }
            System.out.println();
        }
    }
}