How do I sort entered strings NOT using arrays in Java?

So this program is supposed to ask for a list of names. Once the final person's name has been entered. (In my program I use the command 'quit' to end it) It's supposed to show the name that is first alphabetically and the name that is last alphabetically.

Example - If you enter in Zach, Bri, Ben, Joe, quit

The program would display Ben, Zach

I'm stuck on this because this opens up the possibility of any amount of names entered to be compared...

Brand new to programming so don't be too harsh! Thanks! :)