String format into specific pattern

Question

Is there any pretty and flexible way to format String data into specific pattern, for example:

data input -> 0123456789
data output <- 012345/678/9

I did it by cutting String into multiple parts, but I'm searching for any more suitable way.

Answer 1

You can use replaceAll with regex to match multiple groups like so :

String text = "0123456789";
text = text.replaceAll("(\\d{6})(\\d{3})(.*)", "$1/$2/$3");
System.out.println(text);

Output

012345/678/9

details

• (\\d{6}) group one match 6 digits
• (\\d{3}) group two match 3 digits
• (.*) group three rest of your string
• $1/$2/$3 replace with the group 1 followed by / followed by group 2 followed by / followed by group 3

Answer 2

Assuming you want the last and 4th-2nd last in groups:

String formatted = str.replaceAll("(...)(.)$", "/$1/$2");

This captures the parts you want in groups and replaces them with intervening slashes.

Answer 3

You can use StringBuilder 's insert to insert characters at a certain index:

String input = "0123456789";
String output = new StringBuilder(input)
    .insert(6, "/")
    .insert(10, "/")
    .toString();
System.out.println(output); // 012345/678/9