title: Java - Swapping Values and Keys in one Map?
body: <p>I am making an encrypt and decrypt program for my programming class, however I am a year ahead of the group so I thought I'd simplify things by using what I learned last year. I decided to use a Tree Map. What the program does is it takes in a file, reads the first line which contains the encrypt data of how the letters will be coded. It is in a format such as "A->B","B->C","C->A" etc. and then a blank line for line 2 and the third line contains the message. I used reg. expressions to remove the char's I do not need from the text file, mapped the Keys to the first letter and then set those values to the arrowed letter. (A is key, B is value) So if the message said ABC, it would become BCA. I am wondering, as for decrypting, if there was a way to easily flip the Keys and Values to where if input was, A key = B val, it would swap to B key = A val. Just looking for an easier method than what I am currently doing with collections and iterators.</p>