Replace decimals 1 to 10 with name ("one", "two"..)

Question

I was trying to take a string and then returns a string with the numbers 1 to 10 replaced with the word for those numbers. For example:

I won 7 of the 10 games and received 30 dollars.

should become:

I won seven of the ten games and received 30 dollars.

So I did this:

import org.apache.commons.lang3.StringUtils;

String[] numbers = new String[] {"1", "2", "3","4","5","6","7","8","9","10"};
String[] words   = new String[]{"one", "two", "three","four","five","six",
    "seven","eight","nine","ten"};
System.out.print(StringUtils.replaceEach(phrase, numbers, words));

And the result is this:

I won seven of the one0 games and received three0 dollars.

So I tried a brute force way which I'm sure could be improved with regular expressions or more elegant string manipulation:

public class StringReplace {

  public static void main(String[] args) {
    String phrase = "I won 7 of the 10 games and received 30 dollars.";
    String[] sentenceWords = phrase.split(" ");
    StringBuilder sb = new StringBuilder();
    for (String s: sentenceWords) { 
      if (isNumeric(s)) { 
        sb.append(switchOutText(s));
      }

      else { 
        sb.append(s);
      }
      sb.append(" ");

    }
    System.out.print(sb.toString());
  }

  public static String switchOutText(String s) { 
    if (s.equals("1"))
      return "one";
    else if (s.equals("2"))
      return "two";
    else if (s.equals("3"))
      return "three";
    else if (s.equals("4"))
      return "four";
    else if (s.equals("5"))
      return "fivee";
    else if (s.equals("6"))
      return "six";
    else if (s.equals("7"))
      return "seven";
    else if (s.equals("8"))
      return "eight";
    else if (s.equals("9"))
      return "nine";        
    else if (s.equals("10"))
      return "ten";
    else
      return s;        
  }

  public static boolean isNumeric(String s) { 
    try { 
      int i = Integer.parseInt(s);
    }
    catch(NumberFormatException nfe) { 
      return false;
    }
    return true;
  }

}

Isn't there a better way? Especially interested in regex suggestions.

Answer 1

This approach uses regular expressions to match the target digit surrounded by non-digits (or the start or end character):

String[] words = { "one", "two", "three", "four", "five", "six", "seven",
    "eight", "nine", "ten" };
String phrase = "I won 7 of the 10 games and received 30 dollars.";

for (int i = 1; i <= 10; i++) {
  String pattern = "(^|\\D)" + i + "(\\D|$)";
  phrase = phrase.replaceAll(pattern, "$1" + words[i - 1] + "$2");
}

System.out.println(phrase);

This prints:

I won seven of the ten games and received 30 dollars.

It also copes if the number is the first or last word in the sentence. For instance:

9 cats turned on 100 others and killed 10

correctly translates to

nine cats turned on 100 others and killed ten

Answer 2

Before replacing any number with a word, you need to check that the number is not followed or preceeded by another number. This is probably the only way to be sure that it is not part of a bigger number. So you won't be replacing "30" with "three0" and so on. This will allow it to be "30 " or "30." or "30," or any other punctuation mark. So, the check will have to make sure it is not 0-9.