[dev] question about sheet ?

[Qzi er]

I can't understand the code below  , what's the deference between
"getByIndex( 0 )"   and  "*getByName( OUString::createFromAscii("Sheet2"));
*";

"XSpreadsheetDocument "  and "XSpreadsheets ";

why I need use     Reference< XSpreadsheets > twice ?




        //query for a XSpreadsheetDocument interface
        Reference< XSpreadsheetDocument > rSheetDoc (xComponent, UNO_QUERY);

        //use it to get the XSpreadsheets interface
        Reference< XSpreadsheets > rSheets = rSheetDoc->getSheets();

        //query for the XIndexAccess interface
        Reference< XIndexAccess > xSheetsIA (rSheets, UNO_QUERY);
        Any sheet = xSheetsIA->getByIndex( 0 );
        Reference< XSpreadsheet > rSpSheet (sheet, UNO_QUERY);




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