应用程序的序列化错误java.io.NotSerializableException：

Question

I am trying to run a Vaadin project in google cloud platform using Google Cloud Platform(a plugin in Eclipse). After running in I get this exception:

WARNING: Error in serialization of the application: Class 
rand.TestProject.AutoCrudView$1 must implement serialization.
2019-03-02 15:54:06.159:WARN:oejs.session:qtp1757676444-19: 
java.io.NotSerializableException: java.lang.ref.WeakReference
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at java.util.LinkedList.writeObject(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)

This is the AutoCrudView class:

    @SuppressWarnings("serial")
    public class AutoCrudView  extends Window implements Serializable{
    private static final long serialVersionUID = 1L;

    public AutoCrudView(String PERSISTENCE_UNIT) {
        final HorizontalSplitPanel horizontalSplitPanel = new HorizontalSplitPanel();
        Tree navTree = new Tree();
        navTree.addListener(new Property.ValueChangeListener() {
            /**
             * 
             */
            private static final long serialVersionUID = 1L;

            @Override
            public void valueChange(ValueChangeEvent event) {
                @SuppressWarnings("rawtypes")
                BasicCrudView cv = (BasicCrudView) event.getProperty()
                        .getValue();
                cv.refreshContainer();
                horizontalSplitPanel.setSecondComponent(cv);
            }
        });
        navTree.setSelectable(true);
        navTree.setNullSelectionAllowed(false);
        navTree.setImmediate(true);

        horizontalSplitPanel.setSplitPosition(200,
                HorizontalSplitPanel.UNITS_PIXELS);
        horizontalSplitPanel.addComponent(navTree);
        setContent(horizontalSplitPanel);

        // add a basic crud view for all entities known by the JPA
        // implementation, most often this is not desired and developers
        // should just list those entities they want to have editors for
        Metamodel metamodel = JPAContainerFactory
                .createEntityManagerForPersistenceUnit(PERSISTENCE_UNIT)
                .getEntityManagerFactory().getMetamodel();
        Set<EntityType<?>> entities = metamodel.getEntities();
        for (EntityType<?> entityType : entities) {
            Class<?> javaType = entityType.getJavaType();
            @SuppressWarnings({ "rawtypes", "unchecked" })
            BasicCrudView view = new BasicCrudView(javaType,
                    PERSISTENCE_UNIT);
            navTree.addItem(view);
            navTree.setItemCaption(view, view.getCaption());
            navTree.setChildrenAllowed(view, false);
            if(javaType == Person.class) {
                view.setVisibleTableProperties("firstName","lastName", "boss");
                view.setVisibleFormProperties("firstName","lastName", "phoneNumber", "street", "city", "zipCode", "boss");
            }

        }

        // select first entity view
        navTree.setValue(navTree.getItemIds().iterator().next());
    }

    }

As you can see I've implemented Serializable but without sucess. This is the image that I got from App Engine window: here

Answer 1

You get that warning about an anonymous inner class (that $1 in the end of class name) not the actual class itself.

So: go hunting where you (accidentally) create an inner class instance and try to persist that one.

Maybe that

new(...) {

Where you add the change listener to your tree object. If so, the question would be whether the listener should be a distinct class that should implement that interface. Or if you are simply doing something wrong by trying to persist something that has such a listener (not being an expert in this framework, I find it suspicious to persist ui elements including listener instances).

Answer 2

您可以尝试在单独的文件中声明Property.ValueChangeListener并检查。