what is the Java equivalent of sscanf for parsing values from a string using a known pattern?
So I come from a C background (originally originally, though I haven't used that language for almost 5 years) and I'm trying to parse some values from a string in Java. In C I would use sscanf. In Java people have told me "use Scanner, or StringTokenizer", but I can't see how to use them to achieve my purpose.
My input string looks like "17-MAR-11 15.52.25.000000000". In C I would do something like:
sscanf(thestring, "%d-%s-%d %d.%d.%d.%d", day, month, year, hour, min, sec, fracpart);
But in Java, all I can do is things like:
scanner.nextInt();
This doesn't allow me to check the pattern, and for "MAR" I end up having to do things like:
str.substring(3,6);
Horrible! Surely there is a better way?
Answer
The problem is Java hasn't out parameters (or passing by reference) as C or C#.
But there is a better way (and more solid). Use regular expressions:
Pattern p = Pattern.compile("(\\d+)-(\\p{Alpha}+)-(\\d+) (\\d+)\\.(\\d+)\\.(\\d+)\\.(\\d+)")
Matcher m = p.matcher("17-MAR-11 15.52.25.000000000");
day = m.group(1);
month= m.group(2);
....
Of course C code is more concise, but this technique has one profit: Patterns specifies format more precise than '%s' and '%d'. So you can use \d{2} to specify that day MUST be compose of exactly 2 digits.