Java中的RegEx替换字符串

Question

I've been trying to replace this mathematical function x^2*sqrt(x^3) to this pow(x,2)*Math.sqrt(pow(x,3))

so this is the regex

/([0-9a-zA-Z\.\(\)]*)^([0-9a-zA-Z\.\(\)]*)/ pow(\1,\2)

it works in ruby, but I can't find a way to do it in java, I tried this method

String function=  "x^2*sqrt(x^3)";

  Pattern p = Pattern.compile("([a-z0-9]*)^([a-z0-9]*)");
  Matcher m = p.matcher(function);

  String out = function;

  if(m.find())
  {
      System.out.println("GRUPO 0:" + m.group(0));
      System.out.println("GRUPO 1:" + m.group(1));
      out = m.replaceFirst("pow(" + m.group(0) + ", " + m.group(1) + ')');
  }
      String funcformat = out;
      funcformat = funcformat.replaceAll("sqrt\\(([^)]*)\\)", "Math.sqrt($1)"); 

      System.out.println("Return Value :"+ funcion );
      System.out.print("Return Value :"+ funcformat );

But still doesn´t work, the output is: pow(x, )^2*Math.sqrt(x^3) as I said before it should be pow(x,2)*Math.sqrt(pow(x,3)) . Thank you!!

Answer 1

As others have commented, regex is not the way to go. You should use a parser. But if you want some quick and dirty:

From Matcher :

Capturing groups are indexed from left to right, starting at one. 
Group zero denotes the entire pattern, so the expression m.group(0)
is equivalent to m.group().

So you need to use m.group(1) and m.group(2) . And escape the caret ^ in your regex.

import java.util.regex.*;

public class Replace {
    public static void main(String[] args) {
        String function=  "x^2*sqrt(3x)";
        Pattern p = Pattern.compile("([a-z0-9]*)\\^([0-9]*)");
        Matcher m = p.matcher(function);
        String out = function;

        if (m.find())   {
            System.out.println("GRUPO 0:" + m.group(1));
            System.out.println("GRUPO 1:" + m.group(2));
            out = m.replaceFirst("pow(" + m.group(1) + ", " + m.group(2) + ')');
        }
        String funcformat = out;
        funcformat = funcformat.replaceAll("sqrt\\(([a-z0-9]*)\\^([0-9]*)]*\\)", "Math.sqrt(pow($1, $2))"); 
        System.out.println("Return Value :"+ function );
        System.out.print("Return Value :"+ funcformat );
    }
}