Topic: Regex problem for pattern and grouping

[Donald Fung]

Hi everyone,

I have the following statement, "VARCHAR2 (a,2,c)", and the outputs I want are "a" , "2" and "c".

There're two problems.
1) How can I ignore the "VARCHAR2 (" and ")" by using the pattern?
2) Can the extracted "a", "2", "c" in the same group?

I can use subString & split to process it but I'm looking for idea by using pattern to do the same result.
Thanks.

import java.io.*;
import java.util.*;
import java.util.regex.*;
 
class Test3{
 
    //VARCHAR2({$1})  =   org.ngn.database.type.StringType({$1})
 
    //OK if there are {} for delimiter
    //String regex = "(\\{\\$\\d*\\}?)";
    //String src = "VARCHAR2 ({$1}, {$2})";
    //Output
    //Count:1
    //Group1 :{$1}
    //Group1 :{$2}
 
    String regex = "VARCHAR2 (a,2,c)";
    String src = "(.*?),";  //??
 
    Pattern pattern;
    Matcher matcher;
    boolean found;
 
    Test3(){
        try {
 
            ArrayList strArray = new ArrayList();
 
            try {
 
                Pattern pattern = Pattern.compile(regex);
                Matcher matcher = pattern.matcher(src);
 
                System.out.println("Count:" +matcher.groupCount());
 
                while(matcher.find())
                {
//                    strArray.add((String)matcher.group(1));
                    System.out.println("Group1 :" +(String)matcher.group(1));
 
                    System.out.println();
                }
 
                strArray.trimToSize();
 
//                System.out.println(strArray.toString());
            } catch (Exception e)
            {
            }
 
//            System.out.println((String[])strArray.toArray(new String[0]));
        } catch (Exception e) {
            e.printStackTrace();
        }
 
 
    }
 
    public static void main(String [] argv){
        new Test3();
    }
 
}
 

[Garrett Rowe]

This code will extract all the characters as a group, but the commas are still there. You could use the String.split() method the extract the comma delimited Strings. The regex I came up with presupposes that there will always be at least one comma in the values, no commas outside of the values, but as many values as you want. If these assumptions don't match the actual problem, you'll have to adjust the regex accordingly.
i.e. it will match:
a,b,c
a,b,c,d,e,f
a,
abc,def,ghi

but not:
a
abc

import java.util.regex.*;
public class PatternTest
{
   public static void main(String[] args)
   {
      final String TEXT = "VARCHAR2 (a,b,c,d,e,f)";
      String regex = ""(((\\w)+,)+((\\w)+)*)"";
 
      Pattern pattern = Pattern.compile(regex);
      Matcher matcher = pattern.matcher(TEXT);
 
      while (matcher.find())
      {
         System.out.println(matcher.group());
      }
   }
}

[Donald Fung]

Thanks for your reply.

Finally, I'd updated the pattern to the following to extract the ().
And then I put the result into the matcher agin to get the result.

    
    String src = "VARCHAR2 (('a'),2,c,d,e,f)";
    String regex = "(?:\\()(.+,?)(?:\\))";