sheets = _sheets;
for(int i=0;i<sheets.size();i++){
Element sheet = sheets.get(i);
if(sheet.hasAttr("title")){
name2Sheet.put(sheet.attr("title"), sheet);
name2SheetIndex.put(sheet.attr("title"), i);
index2SheetName.put(i, sheet.attr("title"));
}else{
name2Sheet.put("Spread Sheet"+i, sheet);
name2SheetIndex.put("Spread Sheet"+i, i);
index2SheetName.put(i, "Spread Sheet"+i);