/* 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 re = "#+\\${2}"; 
        String str = "##$$abxcyh###$$shbhs##xcznbx##"; 
		System.out.println(str.replaceAll(re, "\\$\\$"));
		    // or
        re = "#+(\\${2})";  // using capturing and back-references
	    System.out.println(str.replaceAll(re, "$1"));
	}
}

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