Error during Table cache update in vaadin

问题

MY code is:

   BeanItemContainer<TimeCardBean> results = new BeanItemContainer<TimeCardBean> (TimeCardBean.class);
        for (TimeCardBean bean : beans) {
            results.addBean(bean);
        }
      table.setContainerDataSource(results);
      table.addGeneratedColumn("function",new ColumnGenerator(){
      public Object generateCell(final Table source, final Object itemId, final Object columnId) {
      Byte timecardSeq=
     (Byte)source.addItem(itemId).getItemProperty("timeCardSeq").getValue();

     Button btnChange= new Button("Change", new ClickListener() {
     public void buttonClick(final ClickEvent event) {
     TimeCardEditDialog editDialog = new TimeCardEditDialog(viewService);
                            editDialog.init(timecardSeq);
     }
    });
   return btnChange;
}

I get the following error:

com.vaadin.ui.Table$CacheUpdateException: Error during Table cache update. Additional causes not shown. at com.vaadin.ui.Table.maybeThrowCacheUpdateExceptions(Table.java:1716) at com.vaadin.ui.Table.refreshRenderedCells(Table.java:1705) at com.vaadin.ui.Table.refreshRowCache(Table.java:2638) at com.vaadin.ui.Table.addGeneratedColumn(Table.java:4404)

Hope you got when I want to express and can anyone tell me about to do this?

来源：https://stackoverflow.com/questions/24991301/error-during-table-cache-update-in-vaadin