How to take a substring using pattern match

Question

I have

String content= "<a data-hovercard=\"/ajax/hovercard/group.php?id=180552688740185\">
                 <a data-hovercard=\"/ajax/hovercard/group.php?id=21392174\">"

I want to get all the id between "group.php?id=" and "\""

Ex:180552688740185

Here is my code:

String content1 = "";
Pattern script1 = Pattern.compile("group.php?id=.*?\"");
Matcher mscript1 = script1.matcher(content);
while (mscript1.find()) {
    content1 += mscript1.group() + "\n";
}

But for some reason it does not work.

Can you give me some advice?

Try using String.match or String.split -- both take regex. this might help forums.codeguru.com/… — Austin Mueller
– Austin Mueller, Commented Oct 15, 2012 at 14:56

Rohit Jain · Accepted Answer · 2012-10-15 15:32:20Z

2

Why are you using .*? to match the id. .*? will match every character. You just need to check for digits. So, just use \\d.

Also, you need to capture the id and then print it.

// To consider special characters as literals
String str = Pattern.quote("group.php?id=") + "(\\d*)";

Pattern script1 = Pattern.compile(str);
// Your matcher line
while (mscript1.find()) {
    content += mscript1.group(1) + "\n";   // Capture group 1 contains your id
}

edited Oct 15, 2012 at 15:32

answered Oct 15, 2012 at 14:55

Rohit Jain

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7 Comments

shyam Over a year ago

you also need to escape the ? Pattern.compile("group.php\\?id=(.*?)\"");

Hiriji Sakumo Over a year ago

I try that way too but the return string is still null.

Rohit Jain Over a year ago

@HirijiSakumo. Great. Just missed that `\` thanks to Shyam that it got corrected. :)

Mik378 Over a year ago

regexp can be reduced to: "group.php\\?id=(\\d*)" to extract the whole number.

Rohit Jain Over a year ago

@Mik378 Oh yes.. Non-greedy quantifier is not needed here. :)

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