How does the '*' work in the code?

[DrMath]

import java.util.regex.*;
class Regex2 {
public static void main(String[] args) {
Pattern p = Pattern.compile(args[0]);
Matcher m = p.matcher(args[1]);
boolean b = false;
while(b = m.find()) {
System.out.print(m.start() + m.group());
}
}
}
And the command line:
java Regex2 "\d*" ab34ef
What is the result?
A. 234
B. 334
C. 2334
D. 0123456
E. 01234456
F. 12334567
G. Compilation fails

[CodesAway]

Which one, the one in the import statement, or the command-line input?

In the import statement, it's a "star import" - it imports ALL classes in that package. However, it can get you into trouble if two packages have the same class. I saw someone do this by importing java.awt.* and java.util.*. Both have a "List" class, and you can't import two classes with the same name, because the compiler can't figure out which you intended. Also, when working with an IDE (e.g. Eclipse, NetBeans), I've heard star imports can cause problems. I don't use them, I let the IDE import the necessary classes for me, so I'm not sure what kind of problems, or how they occur.

As for the star in the command-line, when it's compiled in the regex, it means "0 or more (of the previous element)". So, in the code above, it means 0 or more digits.

[DrMath]

Commandline...
thanks. :)

[CodesAway]

Welcome.

If you're unfamiliar with regex syntax, check out regular-expressions.info/, which has an amazing regular expression tutorial.