Java - Insert a string into another string

stringInString.java

/**
 * Function that inserts a specified string into another string. It uses java's StringBuilder.
 * Usage: insertStringInString("dogs cats", "and", 4) -> "dogs and cats"
 * @param string - The main string that should contain the new piece
 * @param insertion - The piece to add
 * @param position - The position from which to add the piece
 * @return - The final string
 */
public static String insertStringInString(String string, String insertion, int position) {
  // Only insert if the position is > -1 (useful with string.indexOf which returns -1
  if (position > -1) {
    // Create the string builder and append the insertion at the specified position
    StringBuilder mStringBuilder = new StringBuilder(string);
    mStringBuilder.insert(position, insertion);

    // Return the final string
    return mStringBuilder.toString();
  } else {
    // Return the original string
    return string;
  }
}