Mean Median Range
Write a Java program contained in a single file named "MeanMedianRange.java"
that has the user enter an unlimited number of integers, one per line.  After
the user presses the ENTER key on an empty line by itself, the program should
compute and display the mean, median, and range of the entered numbers (label
the output).  Since the mean and median of a set of integers can be a double,
use the 'printf' method to always display the mean and median (but not the range)
rounded to exactly two decimal places.  Also, be sure to gracefully
handle the case where the user does not enter any numbers, as well as the
case where the user enters only one number.

For this program you should use the 'ArrayList' class to create an array of
Integers (the list must contain integers, not strings).  In addition to
'main', you should have a separate method that gets the integers from the
user, another method that computes and displays the mean, another method for
computing and displaying the median, and another method to compute and display
the range of the numbers.  You may use additional methods, if you wish.

In this program you are allowed to use only one ArrayList, and you may not use
any other type of List or Collection anywhere in your program (although you
may use the 'Collections' class to sort your ArrayList).  Other than the
ArrayList of integers, you may not use any global variables for this
assignment.  Also, you must use a 'try-catch' block to error trap for "bad"
user input.  If the user enters a non-integer (a double or a string), discard
the entry, display an appropriate message, and then continue to collect data.


Advanced Option
Create an additional method in your program that computes and displays the
mode(s) of the integers entered by the user.  Remember that a set of numbers
can have multiple modes.  If you wish, you may use an additional ArrayList
for this advanced option.