match « number « Java Regex Q&A

1. Java Regex for matching hexadecimal numbers in a file    stackoverflow.com

So I'm reading in a file (like java program < trace.dat) which looks something like this:

58
68
58
68
40
c
40
48
FA

2. How do I use a regular expression to match an eight-digit number that can also have a space in the middle?    stackoverflow.com

I want to match 1234 5678 or 12345678 Is this regular expression wrong?

if(!number.matches("^\\d{4}[, ]\\d{4}$")){
  throw new Exception(" number is not valid : "+number);
}

3. Java Regex - need help on number match    stackoverflow.com

I am trying to match all the values 1 to 18 from string 24-15-7-49-63-2 using regex. I used regex before for general purpose but I don't have any idea how to ...

4. Regular Expression match number of lines    forums.oracle.com