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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4. import java.util.regex.*;
  5.  
  6. class Ideone
  7. {
  8. 	public static void main (String[] args) throws java.lang.Exception
  9. 	{
  10. 		Matcher m1 = Pattern.compile("(test1)(test2)?(test3)").matcher("test1test3");
  11. 		if(m1.matches()) {
  12. 			for(int g=1;g<=m1.groupCount();g++){
  13. 				System.out.println("Group "+g+": "+m1.group(g));
  14. 			}
  15. 		}
  16. 		System.out.println("--------------");
  17. 		Matcher m2 = Pattern.compile("(test1)()(test3)").matcher("test1test3");
  18. 		if(m2.matches()) {
  19. 			for(int g=1;g<=m2.groupCount();g++){
  20. 				System.out.println("Group "+g+": "+m2.group(g));
  21. 			}
  22. 		}
  23. 	}
  24. }
Success #stdin #stdout 0.08s 380160KB
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stdin
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Standard input is empty
stdout
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Group 1: test1
Group 2: null
Group 3: test3
--------------
Group 1: test1
Group 2: 
Group 3: test3
https://ideone.com/vdbAlq
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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