Question

I want to generate a String with 11 digits from an ID.
For example:
an account with an ID=12 would give 00000000012

And after that I need to retrieve this id from the string.

For example:
a string with 00000000022 give an ID=22

Answer 1

To format the string, use String.format:

int n = 123;
String.format("%011d", 123);
// ===> 00000000123

To get the number back from string, use Integer.parseInt:

Integer.parseInt("00000000123");
// ====> 123