replacing a particular pattern in a string with an auto incrementing number

Question

I have a string like "Hello how Hello are Hello" I want to replace the number of times "Hello" occurs in the above string by an autoincrementing number.

Like "1 how 2 are 3"

"Hello" can occur any number of times

Answer 1

try this simple method:

public static String transform(String input) {
    StringBuilder stringBuilder = new StringBuilder();
    int i = 1;

    for (String s : input.split("Hello")) {
        stringBuilder.append(String.format("%s %d", s, i++));
    }

    return stringBuilder.toString();
}

Sample usage

public static void main(String[] args) {
    String i = "Hello how Hello are Hello";
    System.out.println(transform(i));
}

Answer 2

I don't know felt the need to do it with recursion.

public class StringReplacement {

    private static final String HELLO = "Hello";

    /**
     * @param args
     */
    public static void main(String[] args) {
     String stringToTransform = "Hello how Hello are Hello";
     System.out.println(transform(stringToTransform));
    }

    private static String transform(String stringToTransform) {
     return transform(stringToTransform, 1);
    }

    private static String transform(String stringToTransform, int counter) {

     String output = stringToTransform.replaceFirst(HELLO, String
             .valueOf(counter));

     if (output.contains(HELLO))
      return transform(output, ++counter);
     else
      return output;
    }

}

Answer 3

Use regular expressions. Here is how