How to get a char sequence from String that contains a searched string

Question

I would like to know if their is a function in JAVA that allows to retrieve from a huge string a char sequence that contains a special char.

Example: I have a php page that that I've stringified and I check if there is a char sequence containing the char "@". If it's the case, I would like to get just the whole char sequence that contains the searched char.

I can use String.contains("@") to look for the char but how to get the char which contains it ?

Thanks in advance !

What do you mean by "a char sequence that contains the char"? The whole string is a char sequence that contains it. So which char sequence do you mean? — RealSkeptic, Jun 20 '15 at 16:04
Imagine, "mailto = [email protected]" is the whole string. I've got to know that the string contains the searched char "@" but now how to retrieve "[email protected]"... — Hubert Solecki, Jun 20 '15 at 16:09
You should be able to define a set of characters preceding and/or following `@` to delimit the surrounding substring. — laune, Jun 20 '15 at 16:09

score 2 · Accepted Answer · edited May 23 '17 at 12:29

You can use a regular expression based on

"mailto = ([email protected])"

If this is found in the stringified php, you can conveniently extract the parenthesized section.

But most likely it could be [email protected] as well, and so you may have to write a more complicated regular expression, but it'll work the same way.

Here's a version matching any valid email address:

"mailto = ([A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+(?:\\.[A-Za-z]){1,3}\\b)"

Perhaps the spaces before and after = aren't guaranteed, so you might make them optional:

"mailto ?= ?(...)"

To execute the match, use

Pattern pat = Pattern.compile( "mailto = ([A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+(?:\\.[A-Za-z]){1,3}\\b)" );

and, with the php in a String you can then do

String php = ...;
Matcher mat = pat.matcher( php );
if( mat.find() ){
    String email = mat.group( 1 );
}

The find can be called repeatedly to find all occurrences.

See another SO Q+A for the discussion of a regular expression matching an email address.

I just noticed that the pattern I grabbed from somewhere was missing a parentheses to combine the repeated ".xxx" in the second part. fixed. — laune, Jun 20 '15 at 16:25

score 1 · Answer 2 · answered Jun 20 '15 at 16:16

Since the regex idea was already taken, here's another approach

String test = "abc 123 456@789 abcde";
String charToFind = "@";

String strings[] = test.split(" ");
for( String str : strings ){
  if( str.contains(charToFind) ){ System.out.println(str); }
}

score 0 · Answer 3 · answered Jun 20 '15 at 16:07

0

You could use a combination of indexOf and substring to find and extract the substring.

Without more info on how the source and the searched string look like it's hard to help you further.

answered Jun 20 '15 at 16:07

wonderb0lt

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Please don't write comments as answers. – laune Jun 20 '15 at 16:08
@laune I thought this one was on the line, but I appreciate your feedback – wonderb0lt Jun 20 '15 at 18:42
1

If you'd have backed it up with a snippet of code, I'd agree with you. – laune Jun 20 '15 at 18:44
Fair enough, I'll keep it in mind for next time I'm in a similar situation. :) – wonderb0lt Jun 22 '15 at 08:31

How to get a char sequence from String that contains a searched string

3 Answers3