Regular expression to convert an RGB string to an RGBa string

Question

I am using String#replace() to convert an RGB string into an RGBa one. This is the current code:

inputString = "rgb(255, 182, 121)";
outputString = inputString.replace( "rgb", "rgba" ).replace( ")", ",255)" ).replace( " ", "" );

In the example above, the output will be "rgba(255,182,121,255)". This solution, however, looks a bit convoluted, and I think it could be done more elegantly using a regular expression.

How can I write a regular expression (in Java) to accomplish the same thing as the code above?

Isn't that working for you? If the strings you need to change are in the known format, why change anything? — Wiktor Stribiżew, Dec 01 '16 at 11:36
@WiktorStribiżew regular expression gives the more specifc solution thats why I want to try that way — Avinash Jadhav, Dec 01 '16 at 11:40
`replaceAll` takes a regular expression. `replace` does not. — Elliott Frisch, Dec 01 '16 at 11:43
You should be aware that at the moment the Stack Overflow community [does not approve of "give me a regex that does..." questions](http://meta.stackoverflow.com/q/285733/4125191). — RealSkeptic, Dec 01 '16 at 11:44
Possible duplicate of [Regular expression in java](http://stackoverflow.com/questions/5278322/regular-expression-in-java) — Avinash Jadhav, Dec 21 '16 at 13:42

Vampire · Accepted Answer · 2016-12-01T11:43:41.023

2

Sure you can:

    inputString.replaceFirst("rgb\\((\\d++),\\s*(\\d++),\\s*(\\d++)\\)", "rgba($1,$2,$3,255)");

If you use it more often, better pre-compile the regex with Pattern.compile().

edited Dec 01 '16 at 11:43

answered Dec 01 '16 at 11:40

Vampire

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Regular expression to convert an RGB string to an RGBa string

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