HashSet < String > checkDupColumnNames ( ) { HashSet < String > conflictingNames = new HashSet <> ( ) ; if ( null == _column_names ) return conflictingNames ; HashSet < String > uniqueNames = new HashSet <> ( ) ; for ( String n : _column_names ) if ( ! uniqueNames . add ( n ) ) conflictingNames . add ( n ) ; return conflictingNames ; }
Set of duplicated column names