Question

我正在根据vaadin 8的CRUD示例构建一个项目。

我有一个网格打开页面右侧的表单，此表单有一个取消按钮，可以关闭此表单并清除网格选择。

我收到了这个错误：

com.vaadin.event.ListenerMethod $ MethodException：方法的调用 selectionChange in com.vaadin.ui.components.grid.SingleSelectionModelImpl $ 2 $$ LAMBDA $1190062771分之352 失败。

这是stackTrace：

com.vaadin.event.ListenerMethod$MethodException: Invocation of method selectionChange in com.vaadin.ui.components.grid.SingleSelectionModelImpl$2$$Lambda$352/1190062771 failed.
at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:519)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:273)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:237)
at com.vaadin.server.AbstractClientConnector.fireEvent(AbstractClientConnector.java:1014)
at com.vaadin.ui.components.grid.SingleSelectionModelImpl.setSelectedFromServer(SingleSelectionModelImpl.java:179)
at com.vaadin.ui.components.grid.SingleSelectionModelImpl.deselect(SingleSelectionModelImpl.java:90)


Caused by: java.lang.NullPointerException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)

有什么想法吗？我的对象不是空的。

    public void clearSelection() {
       try {
            grid.getSelectionModel().deselectAll();
       } catch (Exception e) {
        e.printStackTrace();
       }
     }

我在视图类上的网格初始化代码：

 grid = new GridViagem();
        grid.setDataProvider(dataProvider);
        grid.asSingleSelect().addValueChangeListener(
                event -> viewLogic.rowSelected(event.getValue()));

Answer 1

发现问题，我每次选择一行时都会调用一个函数

 public void editProduct(Product product) {
    if (product == null) {
        product = new Product();
    }
    currentProduct = product;
    binder.readBean(product);

    // Scroll to the top
    // As this is not a Panel, using JavaScript
    String scrollScript = "window.document.getElementById('" + getId()
            + "').scrollTop = 0;";
    Page.getCurrent().getJavaScript().execute(scrollScript);
}

由于某种原因，当我的实体为null时，binder.readBean（product）;得到一个空指针，即使我已实例化product = new Product（）;

在示例中，我获得了代码，实体具有默认值，因此我将代码更改为：

        if (viagem == null) {
            viagem = new Viagem();
            currentViagem = viagem;
            binderViagem.removeBean();
        } else {
            currentViagem = viagem;
            binderViagem.readBean(viagem);
        }

Vaadin网格清晰选择行

1 个答案: