Why does replaceAll fail with “illegal group reference”?

Question

I am in need to replace

\\\\\\s+\\\\$\\\\$ to $$

I used

String s = \"  $$\";
s = s.replaceAll(\"\\\\s+\\\\$\\\\$\",\"$$\"         


        

Answer 1

This is the right way. Replace the literar $ by escaped \\$ str.replaceAll("\\$", "\\\\\\$")