/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
/* 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
	{
		// your code goes here
        final String regex = "\\w(?=\\w*?\\[)";
        final String string = "any prefix [tag=foo]bar[/tag] any suffix\n"
             + "any prefix [tag=foo]longerbar[/tag] any suffix";
        final String subst = "*";
 
        final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
        final Matcher matcher = pattern.matcher(string);
 
        // The substituted value will be contained in the result variable
        final String result = matcher.replaceAll(subst);
 
        System.out.println("Substitution result: " + result);
	}
}

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