Java Classwork #2 (SchoolYears)
02) For your second Java classwork you are to write a program contained in a single
    file that displays a message telling the educational level of a student based on
    his/her number of years of school. The user should be prompted to enter an integer
    indicating the number of years of school, and the program should then print the
    corresponding message given below.

    If years of school is      Then the message should be
      less than 0                The years in school must be a non-negative integer.
      0                          Education level:  No school
      1 - 5                      Education level:  Elementary school
      6 - 8                      Education level:  Middle school
      9 - 12                     Education level:  High school
      > 12                       Education level:  College

    You may assume that the user will always enter an integer.  Be sure to keep your
    logical expressions as simple as possible.  You will lose points if they are
    unnecessarily complex (no compound 'if' statements should be used).  Also, for
    this program you must use named global constants for all numbers other than zero.
    In other words, no number other than zero should appear in 'main' or in any of
    the other methods in your program.  Make sure your program contains no more than
    four named constants, which should be named using all capital letters.

    You may not use any global variables for this assignment.  Your program should
    contain exactly two methods (in addition to 'main').  One of the methods should
    be named "getYears" and should get the number of school years from the user.
    The other method should be named "showSchool" and should display the appropriate
    school level to the user.  Both of these methods must be called from 'main'.
    Your program's output should be neat, organized, and grammatically correct,
    similar to what is shown below.

    Sample Output #1
      Enter the number of years in school:    7
      Education level:  Middle school

    Sample Output #2
      Enter the number of years in school:    12
      Education level:  High school

    Sample Output #3
      Enter the number of years in school:    -4
      The years in school must be a non-negative integer.


ADVANCED OPTION FOR CLASSWORK #2
    Instead of asking for the number of years in school just one time, have
    your program ask for a number of years, display the proper output, then
    ask for another number of years, then display the correct output, then ask
    for more years, and so on.  Keep doing this until the user presses the
    ENTER key without entering any data at all.  In addition, after the user
    presses the ENTER key by itself to quit the program, display a small table
    showing the number of times that each level of education was displayed,
    along with the percent value of the total number of entries.  Make sure
    the values are nicely aligned in neat columns and the percent values are
    rounded to one decimal place.