java regex insert character as specific index position

Question

I need to simply insert character "/" in the 3rd position of string.

ie "EURUSD" becomes "EUR/USD".

I'm using some program GUI to do this, it accepts a Regex Pattern and a Replacement.

I know this must be super simple but I can't seem to find a simple answer.

Ry- · Accepted Answer · 2015-12-27 01:57:11Z

3

Replace ^.{3} (3 [{3}] characters [.] at the start of the string [^]) with $&/ (the match $&, followed by a /).

answered Dec 27, 2015 at 1:57

Ry-♦

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Comments

Bohemian · Accepted Answer · 2015-12-27 02:10:57Z

1

Use a look behind:

str = str.replaceAll("(?<=^...)", "/");

Using a look behind, which doesn't consume any input, means the replacement term is simply your new character (no need for back references).

answered Dec 27, 2015 at 2:10

Bohemian♦

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