A common programming challenge is joining a list with a different separator between the final two items. For example, joining a list with ", " as the primary separator but " and " as the final separator. Take a look at this Stack Overflow question to see just how awkward the current solutions are.
I propose that we extend StringUtils with three additional methods:
This could also be added to the other join methods for primitives, but I suspect the primary use case will be strings and I don't suggest we pollute the class any further.
Below shows the expected pseudo output using ", " and " and ":