/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String text = "This_is_a_[sample]_text[notworking]";
		Matcher matcher = Pattern.compile("\\[([a-zA-Z_]+)\\]").matcher(text);                                     
		int i = 0;
		while (matcher.find()) {
		    for (int j = 0; j <= matcher.groupCount(); j++) {
			    System.out.println("------------------------------------");
			    System.out.println("Group " + i + ": " + matcher.group(j));
			    i++;
			}
		}
	}
}

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