Extract String from another string in Java

Question

Here is a string:

"http://l2.yimg.com/bt/api/res/1.2/iis49xBsStLiYI6LjauR6Q--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTg2O3E9NzU7dz0xMzA-/http://media.zenfs.com/fr_FR/News/LeMonde.fr/1515504_3_f73c_le-cyber-harcelement-est-une-realite-trop-lo_450282425a88c544c2ff4121a5d9dab4.jpg"

This string is a concatenation of two URLs. I would like to extract only the second URL:

"http://media.zenfs.com/fr_FR/News/LeMonde.fr/1515504_3_f73c_le-cyber-harcelement-est-une-realite-trop-lo_450282425a88c544c2ff4121a5d9dab4.jpg"

How can I do that using Java?

A simple str.substring(str.indexOf("http://", 1)) is enough. — Marko Topolnik
– Marko Topolnik, Commented Feb 5, 2014 at 13:14
I like str.substring(108). It does exactly what the poster asked for. — robert
– robert, Commented Feb 5, 2014 at 15:20

Bohemian · Accepted Answer · 2014-02-05 13:12:03Z

2

Remove everything up to "http://" not found at the start:

String url2 = str.replaceAll("(?i).+(?=https?://)", "");

This will work case insensitively and match http or https protocols.

answered Feb 5, 2014 at 13:12

Bohemian♦

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6 Comments

Marko Topolnik Over a year ago

+1 for handling https, although I hardly believe case insensitivity is necessary.

Bohemian Over a year ago

thanks, but I'm working pro bono atm - capped out hours ago :)

The Guy with The Hat Over a year ago

+1; I didn't know that you can use (?<flags>) in java.

Bohemian Over a year ago

@RyanCarlson afaik (?ims) are supported. global is on by default.

The Guy with The Hat Over a year ago

It doesn't say anywhere on Pattern's summary, but I did find another interesting thing: in the regex (abc((?i)xyz), xyz is case insensitive, but abc isn't.

|

A Paul · Accepted Answer · 2014-02-05 13:14:02Z

2

Try this. "str" is the url string

System.out.println(str.substring(str.lastIndexOf("http:")));

answered Feb 5, 2014 at 13:14

A Paul

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Comments

ashes999 · Accepted Answer · 2014-02-05 13:14:31Z

2

If you want to extract the URL, just find the last instance of http, and take the substring:

String secondUrl = firstUrl.substring(firstUrl.lastIndexOf("http"));

answered Feb 5, 2014 at 13:14

ashes999

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Comments

The Guy with The Hat · Accepted Answer · 2014-02-05 13:20:24Z

1

Try using string's .split() method, like this:

String oneURL = twoURLs.split("(?<!^)(?=http://)")[1];

This splits the string in places that are not at the end of the string, but are followed by http://. With that, you should end up with an array like this:

["http://l2.yimg.com/bt/api/res/1.2/iis49xBsStLiYI6LjauR6Q--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTg2O3E9NzU7dz0xMzA-/", "http://media.zenfs.com/fr_FR/News/LeMonde.fr/1515504_3_f73c_le-cyber-harcelement-est-une-realite-trop-lo_450282425a88c544c2ff4121a5d9dab4.jpg"]

[1] takes only the second element of that array.

Explanation and demonstration of the regex here: http://regex101.com/r/eW6mZ0

edited Feb 5, 2014 at 13:20

answered Feb 5, 2014 at 13:13

The Guy with The Hat

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