/**
 * This Class converts capitals to lower case and
 * small letters to capitals, without changing of
 * special characters.
 * @author Droxl
 */
public class LetterConverter {
    /**
     * This method changes the character to lower case.
     * @param c The character which is given.
     * @return Returns the lower case character.
     */
    public static char getLowerCase(char c) {
        c = Character.toLowerCase(c);
        return c;
    }
    /**
     * This method changes the character to upper case.
     * @param c The character which is given.
     * @return Returns the upperer case character.
     */
    public static char getUpperCase(char c) {
        c = Character.toUpperCase(c);
        return c;
    }
    /**
     * This method converts capitals to upper or lower case.
     * It depends on which type character is given.
     * @param c The given character.
     * @return Returns the opposite of the
     * type of character which is entered.
     */
    public static char convertLetter(char c) {
        /*This character serves as return-value.*/
        char returnValue;
        /*Here the converting begins...*/
        if ((c == 'a') || (c == 'b') || (c == 'c')
                || (c == 'd') || (c == 'e') || (c == 'f')
                || (c == 'g') || (c == 'h') || (c == 'i')
                || (c == 'j') || (c == 'k') || (c == 'l')
                || (c == 'm') || (c == 'n') || (c == 'o')
                || (c == 'p') || (c == 'q') || (c == 'r')
                || (c == 's') || (c == 't') || (c == 'u')
                || (c == 'v') || (c == 'w') || (c == 'x')
                || (c == 'y') || (c == 'z')) {
            /*...to capitals.*/
            returnValue = getUpperCase(c);
                } else {
            /*In the other case to small letters.*/
            returnValue = getLowerCase(c);
        }
        /*Returns capital or lower case letters depending on what is entered.*/
        return returnValue;
    }
    /**
     * Main-method() which executes the given methods above.
     * @param args is not used.
     */
    public static void main(String[] args) {
        /*Converts to --> A.*/
        System.out.println(convertLetter('a'));
        /*Converts to --> a.*/
        System.out.println(convertLetter('A'));
        /*Keeps steady @.*/
        System.out.println(convertLetter('@'));
        /*Converts to --> B.*/
        System.out.println(convertLetter('b'));
        /*Converts to --> b.*/
        System.out.println(convertLetter('B'));
        /*Keeps steady @.*/
        System.out.println(convertLetter('@'));
    }
}