Vaadin shuffle ListSelect

Question

如何打乱ListSelect的项目？

所以我有一个 ListSelect 显示项目，在我单击按钮后，我希望项目按顺序随机排列。

仅供参考：我正在使用Vaadin 7和Eclipse Mars。

编辑：

final VerticalLayout layout = new VerticalLayout();
        final Button button = new Button("Run");
        ListSelect select = new ListSelect();
        select.setRows(1000);
        select.setNullSelectionAllowed(false);
        select.addItems("Item1","Item2","Item3","Item3");
        //Shuffle the list
        button.addClickListener();
        layout.addComponents(button, select);
        layout.setMargin(true);
        layout.setSpacing(true);
        setContent(layout);
    }

Answer 1

使用 BeanItemContainer 类来发挥自己的优势：

    protected void init(VaadinRequest request) {
    final HorizontalLayout layout = new HorizontalLayout();
    final Button button = new Button("Run");
    final ListSelect select = new ListSelect();
    select.setNullSelectionAllowed(false);
    final List<ItemBean> list = new LinkedList();
    //Add elements to list
    list.add(new ItemBean("Item1", 1));
    list.add(new ItemBean("Item2", 2));
    list.add(new ItemBean("Item3", 3));
    list.add(new ItemBean("Item4", 4));
    list.add(new ItemBean("Item5", 5));
    final BeanItemContainer<ItemBean> beanBeanItemContainer = new BeanItemContainer<>(ItemBean.class);
    beanBeanItemContainer.addAll(list);
    select.setContainerDataSource(beanBeanItemContainer);

    //Shuffle the list
    button.addClickListener(new Button.ClickListener() {
        @Override
        public void buttonClick(Button.ClickEvent clickEvent) {
            select.removeAllItems();
            Collections.shuffle(list);
            beanBeanItemContainer.addAll(list);

        }
    });
    layout.addComponents(button);
    layout.addComponent(select);
    layout.setMargin(true);
    layout.setSpacing(true);
    setContent(layout);
}

你的 Bean 类可以定义如下：

public class ItemBean implements Serializable  {
    String name;
    int id;
    public ItemBean(String name, int id) {
        this.name = name;
        this.id = id;
    }
    @Override
    public String toString() {
        return this.name;   
    }
}

如果您有任何其他问题，请告诉我！