修复java中交错的正则表达式替换输出

Question

I am trying to get every regex match on its own line with commas in between each element in the line, I have tried to methods to this, but both times the results are staggered for some reason, I replaced the regex and output with a something simpler just to show it, for example the results would look like

1 ,   , 
  , a ,
  ,   , b

when the results should be

1 , a , b

With a new line for the next match

Here are both attempt I tried, this is java

input.replaceAll("(1)|(a)|(b)" , "$1 , $2 , $3 \\n");

and

(match.group(1) + "," + match.group(2) + "," + match.group(3));

the file the is being parsed looks like this for example

1 a b

How would i fix the output so its not staggered ?

Answer 1

As far as I can understand this could be of help:

input.replaceAll("(1).*?(a).*?(b)" , "$1 , $2 , $3 \n");

All will be captured with one replace.

But please explain more what behavior do you expect, because that's not exactly clear, eg "with commas in between each element in the line"

Answer 2

Here's a way to do it:

import java.util.regex.*;

public class Test
{
     public static String process(String s)
     {
         Pattern p = Pattern.compile("1|a|b");
         Matcher m = p.matcher(s);
         StringBuilder sb = new StringBuilder();
         while(m.find())
         {
             if(sb.length()>0)
                sb.append(" , ");
            sb.append(m.group());
         }
         return sb.toString();
     }

     public static void main(String[] args)
     {
         System.out.println(process("1 a b"));
     }
}