Trouble with regular expressions

[laredotornado]

Hi,

I was hoping someone could help me with a simple regular expression
dilemma. I'm using Java 1.5. I have this code:

String regex = accountid; // value is
9998698989898
System.out.println("regexp:" + regex);
Pattern p1 = Pattern.compile(regex);
Matcher m1 = p1.matcher(pageString);
System.out.println("m1 group count:" + m1.groupCount());
System.out.println(pageString.indexOf(regex));
assertTrue(m1.matches());

The assertion ("m1.matches") fails, even though "pageString.indexOf"
returns a value greater than -1, indicating the string is found. So
I'm missing something fundamental about regular expressions.

Any help is appreciated, - Dave

 

[Roedy Green]

The assertion ("m1.matches") fails, even though "pageString.indexOf"
returns a value greater than -1, indicating the string is found. So
I'm missing something fundamental about regular expressions.

You need to post a complete little program, not just rough fragment of
one. See http://mindprod.com/jgloss/sscce.html
The problem is nearly always in the part you did not provide. The
Murphy is in the details.

In the meantime, see http://mindprod.com/jgloss/regex.html
for working examples you can cannibalise to do what you want.

 

[markspace]

The assertion ("m1.matches") fails, even though "pageString.indexOf"
returns a value greater than -1, indicating the string is found. So
I'm missing something fundamental about regular expressions.

m1.matches() means "the regex matches the WHOLE STRING", not some
portion of it.

Use m1.region(int start, int end) to restrict the matches() method to
one part of your input string.

Or use find() (or lookingAt()) to match substrings (indexOf() uses
find(), I believe).

 

[laredotornado]

m1.matches() means "the regex matches the WHOLE STRING", not some
portion of it.

Use m1.region(int start, int end) to restrict the matches() method to
one part of your input string.

Or use find() (or lookingAt()) to match substrings (indexOf() uses
find(), I believe).

Indeed, when I changed to "find" instead of "matches", everything
worked out great. 5 stars. - Dave

 

[markspace]

Indeed, when I changed to "find" instead of "matches", everything
worked out great. 5 stars. - Dave

The Java doc is not really clear, imo, for the matches() method. The
one line documentation for that method is OK, if you already know what
matches() does. If you don't, the significance of the word "entire" in
that sentence is easy to miss.

However, there's often nice code examples on the 'net. One thing you
should always do when confronted with a problem with a class is to
Google for "java <class_name> tutorial", which will often find good
information on how to use the class in question.

For Matcher, the first link is this one:

<http://java.sun.com/docs/books/tutorial/essential/regex/matcher.html>

which has quite a lot of nice examples, including examples of how
matches(), find() and lookingAt() work and differ.

 

[Roedy Green]

The thing you're missing may be the difference between
the matches(), find(), and lookingAt() methods of Matcher.
Why would Matcher have three different methods to search for
the same regular expression? Perhaps the Javadoc will reveal
how the three methods are dissimilar ...

If you find those docs unclear, see
http://mindprod.com/jgloss/regex.html#MATCHINGANDFINDING

 

[Sreenivas]

This post is not related to Java, since i follow this group regularly i
am posting this.
I use ThunderBird for Usenet . I always like to see Usenet in thread
view.If want to store or preserve that thread ,is there any tools or
plugins available for this in ThunderBird?


Best,
Srinivas Reddy Thatiparthy.

 

[Sreenivas]

This post is not related to Java, since i follow this group regularly i
am posting this.
I use ThunderBird for Usenet . I always like to see Usenet in thread
view.If want to store or preserve that thread ,is there any tools or
plugins available for this in ThunderBird?


Best,
Srinivas Reddy Thatiparthy.

My apologies for posting in somebody's thread.It's a mistake.

 

[Daniel Pitts]

Hi,

I was hoping someone could help me with a simple regular expression
dilemma. I'm using Java 1.5. I have this code:

String regex = accountid; // value is
9998698989898
System.out.println("regexp:" + regex);
Pattern p1 = Pattern.compile(regex);
Matcher m1 = p1.matcher(pageString);
System.out.println("m1 group count:" + m1.groupCount());
System.out.println(pageString.indexOf(regex));
assertTrue(m1.matches());

The assertion ("m1.matches") fails, even though "pageString.indexOf"
returns a value greater than -1, indicating the string is found. So
I'm missing something fundamental about regular expressions.

Any help is appreciated, - Dave

Matcher.matches says the whole sequence matches.

What you are possibly wanting is Matcher.find

Also, you may want to use Pattern.compile(accountid, Pattern.LITERAL);