String String add special symbols

STG = String " 20,190,101 ";
 // increase bars at position 4 String - 
String stg.replaceAll STN = ( " ({4}). " , " $ L- " );
 // in the upper hierarchy based on after seven bars increases -, can be considered a bar 
String sTnI, and it stn.replaceAll = ( " ({}. 7). " , " $ l- " ); 
String SOP2 = stni.substring ( 0 , stni.length () - . 1 ); 
System.err.println (SOP2); 

output is: 2019 - 01 - 01