java.util.Scanner

[Lorenz Baylon]

Hi, im trying to parse a text file using the java.util.Scanner.
my trouble is that by default, the Scanner parses the line like this:

(example line) Joe: 38

when i parse this line using the pattern ':' , what i get is 'Joe'.
what i want to achieve is to parse the line so that i will be able to get '38' instead.

Thanks a lot in advance.

lhorenz

[Jim Yingst]

I'd try something like

scanner.useDelimiter("^.*:\\s*");

If that doesn't work for you, please provide some more sample lines of the file to see what sort of variety you have there.

[Lorenz Baylon]

Thank you, it works!

Can we try it for a line in my real world?
the line goes like this:

String theLine = "Name: lhorenz AreaCode: 054 Book: 0012C Page: 00260";

I've tried using:
Scanner lineScanner = new Scanner(theLine);
lineScanner.useDelimiter("^.*Name:\\s*");

the result is " lhorenz AreaCode: 054 Book: 0012C Page: 00260"

maybe you could give me a hint so i could just get "lhorenz" for the value of "Name:", "054" for AreaCode and so on.

I really appreciate the help, I really dont want to resort to using substring method and other String methods as much as possible.

Again, many thanks and regards

lhorenz

[Garrett Rowe]

You can do it using the java.util.regex.Pattern and java.util.regex.Matcher classes. There's a little bit of a learning curve involved though.

import java.util.List;
import java.util.ArrayList;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class MatchTest
{
   public static void main(String[] args)
   {
      String theLine = "Name: lhorenz AreaCode: 054 Book: 0012C Page: 00260";
 
      //match 1 or more word characters followed by a colon followed by one or more whitespaces
      //followed by one or more word characters, and capture the last group
      String regex = "\\w+:\\s+(\\w+)";
 
      Pattern pattern = Pattern.compile(regex);
      Matcher matcher = pattern.matcher(theLine);
 
      List<String> myMatches = new ArrayList<String>();
 

      while (matcher.find())
      {
        myMatches.add(matcher.group(1));
      }
 
      for (String str : myMatches)
      {
         System.out.println(str);
      }
   }
}

O/P =

lhorenz
054
0012C
00260

Alternatively you can capture the attrribute type, and name and add them to a Map<String, String>

import java.util.Map;
import java.util.HashMap;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class MatchTest2
{
   public static void main(String[] args)
   {
      String theLine = "Name: lhorenz AreaCode: 054 Book: 0012C Page: 00260";
 
      String regex = "(\\w+):\\s+(\\w+)";
 
      Pattern pattern = Pattern.compile(regex);
      Matcher matcher = pattern.matcher(theLine);
 
      Map<String, String> matchMap = new HashMap<String, String>();
 

      while (matcher.find())
      {
        matchMap.put(matcher.group(1), matcher.group(2));
      }
 
      for (String key : matchMap.keySet())
      {
         System.out.println(key + "\t" + matchMap.get(key));
      }
   }
}

O/P:

AreaCode054
Namelhorenz
Book0012C
Page00260

[Lorenz Baylon]

Cool! really! thanks a lot folks! It really helps me a lot!

Best regards,
lhorenz

[ak pillai]

Scanner class is a cool addition to JDK 1.5

[Timothy Sam]

OMG! OMG! It's Lhorenz!

Java sure have made a lot of things available these days...

[Lorenz Baylon]

hehe hi Tim!
Follow question.. how do I use Scanner with binary files?

Thanks thanks thanks!