IDocument document = documentService.constructNewDocument(
    IDocument.CALC, DocumentDescriptor.DEFAULT);
ISpreadsheetDocument spreadsheetDocument = (ISpreadsheetDocument) document;
XSpreadsheets spreadsheets = 
  spreadsheetDocument.getSpreadsheetDocument().getSheets();
String sheetName= "Tabelle1";
Object rows = new Object{
  new Object{"DataCell1","DataCell2","DataCell3","DataCell4"},
  new Object{new Integer(10),new Integer(20),new Integer(30),new Integer(40)},
  new Object{new Double(11.11),new Double(22.22),new Double(33.33),new Double(44.44)}};
XSpreadsheet spreadsheet1 = 
  (XSpreadsheet)UnoRuntime.queryInterface(
      XSpreadsheet.class,spreadsheets.getByName(sheetName));
//insert your Data
XSheetCellCursor cellCursor = spreadsheet1.createCursor();
for(int i = 0; i < rows.length; i++) {
  Object cols = rows ;
  for(int j = 0; j < cols.length; j++) {
    XCell cell= cellCursor.getCellByPosition(j,i);
    XText cellText = (XText)UnoRuntime.queryInterface(XText.class, cell);
    Object insert = cols;
    if(insert instanceof Number)
      cell.setValue(((Number)insert).doubleValue());
    else if(insert instanceof String)
      cellText.setString((String)insert);
    else
      cellText.setString(insert.toString());          
  }
}