Question

I have a string which has certain “tokens”.
Example:

"Someone e.g. X here is a # and the other i.e. X is not but over is something else like #"  

I also have a list of String e.g. {"John", "doctor", "Jim","engineer"}

What is the best way to do the following:
I want to replace all the # characters with the corresponding element in the list.

I.e. I want to skip X and John and replace Jim from # and engineer for the other #.
I thought to just loop over the string#toCharArray() but I was interested if there is a better way to do this.

Note: The values in the second list match the corresponding tokens. So the first value in the list i.e. John maps to the first occurence of X or # which ever that is.

Example:

Input: "Someone e.g. X here is a # and the other i.e. X is not but the other is something else like # but X is at least X but not #"
{"John", "doctor", "Jim","John", "engineer", "doctor"}
Output:
"Someone e.g. X here is a doctor and the other i.e. X is not but the other is something else like Jim but X is at least X but not doctor"

Answer 1

You might be interested to look at MessageFormat that allows something similar to this kind of replacement.

E.g.

MessageFormat.format(""
    + "Someone e.g. {0} here is a {1} and the other i.e. {2} " 
    + "is not but over is something else like {3}", 
    new String [] {"John", "doctor", "Jim","engineer"});

Edit:

If the input string cannot be modified to include the placeholders and also the placeholders have special meaning as you mentioned in your update (i.e. X should be ignored, # should be replaced), then you just have to

• initialize the counter to 0.
• create an object of StringBuilder.
• tokenize the input string on space
• iterate through each token
  • if it is X, increment the counter, append the token as is to the StringBuilder object.
  • if it is #, then read the value at index counter from the input array and append that to the StringBuilder object.
  • append a space.
• StringBuilder.toString() and trim to remove the trailing space.