/*
 * T01n15.java -- A text message typed by the user is echoed after
 * each letter is replaced with the same letter in the opposite case.
 * That is, 'b' is replaced with 'B', 'G' is replaced with 'g', etc.
 *
 * When you run this, you type a message and then press Enter.  Computers
 * buffer input, so even though the program is reading a character at
 * a time from the keyboard, the program doesn't see that there's any
 * input to process until the content of the buffer is passed to it.
 * Then it will process the available input, and wait for more to appear.
 *
 * To terminate the program, the user must type the end-of-file (EOF)
 * character for their OS.  Under UNIX-based systems, type Ctrl-D.  
 * Under Windows (DOS), type Ctrl-Z.
 */

import java.util.*;

public class T01n15
{
    public static void main (String [] args)
    {
        char character;
        Scanner keyboard = new Scanner (System.in);

        System.out.println("This program will switch case on your "
                         + "letters.\nNon-alphabetic letters are not "
                         + "changed.\n\nYou will see the conversion only "
                         + "after you press Enter or use\nCtrl-D (UNIX) "
                         + "to terminate the program.\n");

                // hasNext() is true if another 'token' can be read from
                // the underlying stream.

        while (keyboard.hasNext()) {

                // findInLine() is used to locate
                // a pattern of interest within the stream.  In this case,
                // the "." argument says to find a single character.
                // The match is returned as a String.

            character = keyboard.findInLine(".").charAt(0);

            if ( Character.isLowerCase(character) )
                System.out.print(Character.toUpperCase(character));
            else if ( Character.isUpperCase(character) )
                System.out.print(Character.toLowerCase(character));
            else
                System.out.print(character);
        }
    }

}