container.addContainerProperty("col1", String.class, "");
container.addContainerProperty("col2", String.class, "");
container.addContainerProperty("col3", String.class, "");
for (int i = 0; i < 100; i++) {
Item item = container.addItem("item " + i);
item.getItemProperty("col1").setValue("first" + i);
item.getItemProperty("col2").setValue("middle" + i);
item.getItemProperty("col3").setValue("last" + i);
}