Java Regex to get a word from a String

Question

How can I use a regex in java for the following?

String code = "import java.io.*;"  +
              "import java.util.*;"  +
              "public class Test1 extends Exam{" +
                  " // my code " +
              "}";

from the String above how can I get the class name Test1 exactly.

will there always be extends?

amphibient
– amphibient

2013-11-14 16:36:37 +00:00
Commented Nov 14, 2013 at 16:36 — amphibient
– amphibient, Commented Nov 14, 2013 at 16:36
You can use a captured group: /.*class (\S+) .*/

Nir Alfasi
– Nir Alfasi

2013-11-14 16:37:23 +00:00
Commented Nov 14, 2013 at 16:37 — Nir Alfasi
– Nir Alfasi, Commented Nov 14, 2013 at 16:37
yes may be extends or implements..

subash
– subash

2013-11-14 16:37:40 +00:00
Commented Nov 14, 2013 at 16:37 — subash
– subash, Commented Nov 14, 2013 at 16:37

anubhava · Accepted Answer · 2013-11-14 16:53:20Z

1

Use this regex:

String className = code.replaceAll("(?s)^.*?(?:public|protected|private)?\\s*(?:\\s+static\\s+)?class\\s+(\\S+).*$", "$1");
//=> Test1

edited Nov 14, 2013 at 16:53

answered Nov 14, 2013 at 16:37

anubhava

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7 Comments

sp00m Over a year ago

(?:public|protected|private)?(?:\s+static)?\s+class

subash Over a year ago

@anubhava your previous one is work. this updated one is not work.

anubhava Over a year ago

Yes previous one was also working with your example and I had tested it.

subash Over a year ago

perfect experts... thanks a lot @anubhava .. can you please explain shortly how it is work..

anubhava Over a year ago

(?s) is for making dot match new lines. Then it matches any one of public|protected|private keywords followed by optional static and then followed by class. After that it captures \\s+ (i.e. non-space characters) and in the replacement part it replaces whole string with this captured group #1.

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