question: public static String replace ( String s , String sub , String with ) { int c = 0 ; int i = s . indexOf ( sub , c ) ; if ( i == - 1 ) { return s ; } int length = s . length ( ) ; StringBuilder sb = new StringBuilder ( length + with . length ( ) ) ; do { sb . append ( s . substring ( c , i ) ) ; sb . append ( with ) ; c = i + sub . length ( ) ; } while ( ( i = s . indexOf ( sub , c ) ) != - 1 ) ; if ( c < length ) { sb . append ( s . substring ( c , length ) ) ; } return sb . toString ( ) ; }
target:  Replaces all occurrences of a certain pattern in a string with a replacement string. This is the fastest replace function known to author.