Question

I’m using Java to parse strings input by the user, representing either single numeric values or ranges. The user can input the following string:

10-19

And his intention is to use whole numbers from 10-19 –> 10,11,12...19

The user can also specify a list of numbers:

10,15,19

Or a combination of the above:

10-19,25,33

Is there a convenient method, perhaps based on regular expressions, to perform this parsing? Or must I split the string using String.split(), then manually iterate the special signs (‘,’ and ‘-‘ in this case)?

Answer 1

This is how I would go about it:

1. Split using the , as a delimiter.
2. If it matches this regular expression: ^(\\d+)-(\\d+)$, then I know I have a range. I would then extract the numbers and create my range (it might be a good idea to make sure that the first digit is lower than the second digit, because you never know…). You then act accordingly.
3. If it matches this regular expression: ^\\d+$ I would know I have only 1 number, so I have a specific page. I would then act accordingly.