Originally Posted by Mehwish-S
Well, it's a start.
I perceive that you have already recognized that you need a regular expression.
I would make three Strings since it's easier to test one thing at a time.
I would probably call the Strings "firstPart," "separator," and "isecondPart."
Then the regular expression String used in the String.matches()
statement in the final program would simply be firstPart
OK, let's get started...
I would (probably) do the easy part first:
The "separator" is a single space, right? (Wow! We are one third of the way through already!)
Then, I would try to express the other parts in Human Language in a form that can be translated to Regular Expression lingo as spelled out in the Java Regular Expression Tutorial
From your description, I think the Strings would be defined something like the following:
Space: [ ]
In the tutorial, here's where it tells you how you handle repeated fields: Regular Expression Quantifiers
Now if my description turns out not to be completely accurate in terms of accepting valid codes and/or rejecting invalid codes (I'm a Yank, you know; English is just another Foreign Language to me), then you might be able to use my thoughts as a starting point and refine things if your testing turns up problems.
Test, test, and test some more. Give lots of valid codes, but don't just
give it Good Stuff; try to find Bad Stuff that is "almost-but-not-quite" Good.