Decoder Ring - Prompt User For A Message To Decode

So it is the question: This program implements a simple "decoder ring". It will prompt the user for a message to decode and decode the message based on the following substitution rules:

ABCDEFGHIJKLMNOPQRSTUVWXYZ will map to
ZEBRASCDFGHIJKLMNOPQTUVWXY

abcdefghijklmnopqrstuvwxyz will also map to
ZEBRASCDFGHIJKLMNOPQTUVWXY

any other characters (like space, punctuation, will map to themselves)

so if it sees an 'A' (or an 'a'), it will map to 'Z', etc... All i could think of is this but can't figure out the rest.

import java.util.Scanner;
public class DecoderRing
{
public static void main(String[] args)
{
String1[] = 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z';
String2[] = 'Z','E','B','R','A','S','C','D','F','G','H','I','J','K','L','M','N','O','P','Q','T','U','V','W','X','Y';
}
}

Not sure, what things are necessary such as switch statements or if and else or for loops and such...