question: private String join ( String [ ] partials , String separator ) { StringBuilder sb = new StringBuilder ( ) ; for ( int i = 0 ; i < partials . length ; i ++ ) { sb . append ( partials [ i ] ) ; if ( i < partials . length - 1 ) { sb . append ( separator ) ; } } return sb . toString ( ) ; }
target:  Joins a string array, with the given separator.