question: public static String implode ( String [ ] elements , String separator ) { if ( elements == null ) { return null ; } if ( elements . length == 0 ) { return "" ; } StringBuilder builder = new StringBuilder ( ) ; builder . append ( elements [ 0 ] ) ; boolean skippedFirst = false ; for ( String s : elements ) { if ( skippedFirst ) { builder . append ( separator ) ; builder . append ( s ) ; } else { skippedFirst = true ; } } return builder . toString ( ) ; }
target:  Serializes a string array with the specified separator