Question

我收到错误消息：“从内部类引用的局部变量必须是最终的或实际上是最终的”

此错误指的是：

MyTreeItem LeftRootItem = (MyTreeItem) treeViewLeft.getRoot();

我的错误是什么。为什么这个错误不会像“treeViewRight”那样？

addAttribute.setOnAction(new EventHandler<ActionEvent>(){
    @Override
    public void handle(ActionEvent event) {
        TreeView treeViewLeft = new TreeView ();
        treeViewLeft.setShowRoot(false);
        treeViewLeft.setRoot(new MyTreeItem ("root"));
        treeViewLeft.getRoot().setExpanded(true);
        TreeView treeViewRight;
        Button button = new Button ("<<");
        HBox hBox = new HBox ();
        DBConnect.dbconnect();
        treeViewRight = DB.loadAttributeClasses();
        treeViewLeft = DB.getAttributesfromClassorProduct(selectedItem.getClassID());
        treeViewRight.setShowRoot(false);
        treeViewRight.getRoot().setExpanded(true);
        hBox.getChildren().addAll(treeViewLeft, button, treeViewRight);
        Scene scene = new Scene(hBox);

        Stage attributeSelect = new Stage ();
        attributeSelect.setTitle("Hello World!");
        attributeSelect.setScene(scene);
        attributeSelect.show();     

        button.setOnAction(new EventHandler<ActionEvent>(){

            @Override
            public void handle(ActionEvent event) {
                MyTreeItem rightItem = (MyTreeItem) treeViewRight.getSelectionModel().getSelectedItem();
                DB.setProdClassAttr(selectedItem.getClassID(), rightItem.getClassID(), selectedItem.getType());

                rightItem.getParent().getChildren().remove(rightItem);
                MyTreeItem LeftRootItem = (MyTreeItem) treeViewLeft.getRoot();
            }
        });
    }
});

Answer 1

问题是您将两个不同的TreeView分配给treeViewLeft。

你的第4行是

TreeView treeViewLeft = new TreeView ();

然后向下几行，为treeViewLeft分配一个新值：

treeViewLeft = DB.getAttributesfromClassorProduct(selectedItem.getClassID());

如果您想从按钮treeViewLeft处理程序引用onAction，则不允许这样做。

您只需为treeViewRight分配一次值，这是允许的。

从内部类引用的局部变量必须是最终的或有效的最终3

1 个答案: