/* package whatever; // don't place package name! */
import java.util.*;
import java.lang.*;
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 regex = "(\\s)(\\*[^*]+\\*)(\\s)";
String s = "test string *67* **Hi**";
System.out.println(s.replaceAll(regex,"$1hello$3"));
}
}