How to pad after split?

Question

Help!

String all = "1.10.2";
String[] allArray = all.split("[.]");

What I want to do is make string "1.10.2" into 000010001000002 as integer. 00001 00010 00002 so giving padding and making each number into 5 digits and combining them as one integer. What should i do after split()?

Answer 1

You can do it with split like so:

String[] allArray = all.split("\\.");
for (int i = 0; i < allArray.length; ++i) {
  String padding = "0".repeat(5 - allArray[i].length());
  allArray[i] = padding + allArray[i];
}
String padded = String.join("", allArray);

You can do it with streams like so:

String padded = Arrays.stream(all.split("\\."))
    .map(s -> "0".repeat(5 - s.length()) + s)
    .collect(Collectors.joining(""));

You can also do it without explicitly splitting, something like:

String padded =
    Pattern.compile("(?:^|\\.)([^.]+)").matcher(all)
        .replaceAll(mr -> "0".repeat(5 - mr.group(1).length());