Provide a complete program that performs a simple substitution

Provide a complete program that performs a simple substitution cipher. The program should take plain text and a shift value and produce the encrypted text. Then it should take encrypted text and a shift value and produce the plain text once again. A different encrypted text and shift can be entered so make sure to get input.

Example:
EASTER shifted by 3 to left would become HDVWHU
HWVDHU shifted by 3 to right would become EASTER

This is how the early Caesar Cipher worked.

Provide a main method. It should:

Get input for a string and a shift value
Convert to upper case
Only perform the following items on alphabetic characters between A and Z
Utilize a for loop which uses postfix incrementing operator
Convert character to its ASCII equivalent (type cast)
Shift buy shift value entered above
If you reach end of alphabet, wrap around
Example: A shifted to the left 2 would become Y
Convert back to its character equivalent (type cast)
Output the new character
Get input for a string and a shift value
Perform same steps above to convert the encrypted text back to plain text
Be sure to get input again as a different encrypted text may be entered
Utilize postfix increment/decrement operations and compound assignment operators for all math. Example: x++ or x+=2.
80%

Mimic the sample session precisely.
Sample Session:

Please enter text to encrypt
easter
Please enter shift value
3
BXPQBO
Please enter text to decrypt
bxpqbo
Please enter shift value
-3
EASTER
Press any key to continue . . .

Sample Session 2: : (Notice spaces removed from input)

Please enter text to encrypt
This Is A Test
Please enter shift value
3
QEFPFPXQBPQ
Please enter text to decrypt
qefpfpxqbpq
Please enter shift value
-3
THISISATEST
Press any key to continue . . .

Sample Session 3: (Notice the different shift and decrypt value)

Please enter text to encrypt
hello
Please enter shift value
3
EBIIL
Please enter text to decrypt
ebiil
Please enter shift value
5
ZWDDG
Press any key to continue . . .