question: private String [ ] parentKey ( String name , int idx ) { String [ ] parts = name . split ( "\\." ) ; if ( idx > parts . length ) return null ; String parent = "" ; String key = null ; if ( idx < parts . length ) key = parts [ idx ] ; for ( int i = 0 ; i < idx ; i ++ ) { parent = parent . length ( ) > 0 ? parent + "." + parts [ i ] : parts [ i ] ; } return new String [ ] { parent , key } ; }
target:  Splits a name formatted like a.b.c into a parent 'a.b' and key 'c' for a given index (2 in this example)