Hi benjamin pritchard,
First of all - Welcome to JavaRanch.
Now about your program:
Its having a lot more problems, than you explained you're facing.
1. Code is very difficult to read, because there are no methods, and all logic laying down in one single lets by assuming in a "main" method.
You should decompose your program into small methods, so you and your readers could follow your code, and understand what it suppose to do.
2. You're missing curly braces around "if-else" statements - it is error prone, don't take this habit as it is not a good one.
3. Such a lines "System.out.print("Enter selection: ");" doesn't specify what kind of selection user suppose to enter. You should give an options at least.
4. This code below is not doing what you expect from it to do. It should be in a loop, and iterate, while "length != 1".
5. Probably you should work first on the mentioned points above, then look forward what else you have.
6. Probably it would help, if you would write down for yourself all steps program suppose to do in simple English or other native language, and likely you'd see, that current code is not doing what it suppose to do.
Hope it helps.