JAVA:

Create a substitution cypher class

Create a class that has two String arrays as instance variables. The first array will hold the alphabet, one letter per cell. The second array will also hold the alphabet, but in some other order: reversed, random, whatever you want.

Create two methods the first one takes a one-word String and converts it via the two arrays to an encrypted one-word string. The second method takes a one-word String that is already encrypted and returns a one word decrypted String.

Create a test class that asks the user first for a word to be encrypted and it encrypts it. Then asks the user for a word to decrypt and it decrypts it.