Question

我正在尝试使用formlayout格式向vaadin 7中的JPAContainer添加一个新项目。我使用此代码段：

String paramDAO = "PersonDAO";        //this parameter can be acquired from url, http request, data file and etc
Class<?> TC = null;      //DAO class

InitialContext ic;
ic = new InitialContext();
TO = ic.lookup("java:app/MyDAOProject/"+paramDao);   
// PersonDAO class extends JPAContainer<PersonEntity>

container =  (JPAContainer<?>) TO;
T = container.getEntityClass();

if(event.getButton() == newButton)
    {               
        final EntityItem newRecord = container.createEntityItem(T.newInstance());        //eclipse shows syntax error here              
        final EditorWindow editor = new EditorWindow(newRecord, T, visibleColumns, this.entytiPropFactory);

        editor.setCaption("New record");
        editor.addListener(new EditorSavedListener()
            {
                @Override
                public void editorSaved(EditorSavedEvent event) 
                    {
                        container.addEntity(newRecord.getEntity());           //eclipse shows syntax error here
                        new Notification("New record created.", null, Notification.Type.TRAY_NOTIFICATION, true).show(Page.getCurrent());
                    }               
            }                   
        );              
        UI.getCurrent().addWindow(editor);
    }

主要思想是我想创建一个统一的vaadin表，其编辑形式适合我项目中的大多数实体（数据库表）。所以我将dao对象名称作为字符串参数传递（不要问为什么）然后我通过jndi服务查找它。 dao对象与实体绑定并扩展JPAcontainer＆lt; entityClass ＆gt;类。这种方法在Vaadin 6版本中与JPAContainer 2.2.0完美配合，但在迁移到Vaadin 7和JPAContainer 3.0.0后，eclipse在这些行中引发了语法错误（错误在下面的每一行的注释中）：

final EntityItem newRecord = container.createEntityItem(T.newInstance()); 
//The method createEntityItem(capture#9-of ?) in the type JPAContainer<capture#9-of ?> is not applicable for the arguments (capture#10-of ?)

container.addEntity(newRecord.getEntity());
//The method addEntity(capture#12-of ?) in the type JPAContainer<capture#12-of ?> is not applicable for the arguments (Object)

Answer 1

看来你的容器变量声明是这样的：
JPAContainer<?> container;

因此可以通过声明容器变量来避免警告：
JPAContainer<Object> container;
或者这个：
JPAContainer container;

在这里，您将找到有关java泛型中通配符的一些其他信息： http://docs.oracle.com/javase/tutorial/extra/generics/wildcards.html

Vaadin 7 createEntityItem和JPAContainer Eclipse的addentity在代码中显示语法错误

1 个答案: