PLEASE answer whatever you can.. and as soon as possible! JAVA

Complete the recursive function below, which replaces every occurrence of character c1 by character c2 in the input string str. For example: replaceRec("abracadabra", 'b', 'B') should return "aBracadabra" public static String replaceRec(String str, char c1, char c2){ if (str.length() 0) return str; if ( D{ return } else { return } } 7 A- B I iii E E $$ ! O U s X2 x2 h