我正在学习如何在 javafx 中创建一个对话框，我编写了一个给我带来问题的代码。错误在 createLoginDialog 方法中。
错误显示“无法访问 TryDialogBox 类型的封闭实例。必须使用 TryDialogBox 类型的封闭实例限定分配（例如 xnew A()，其中 x 是 TryDialogBox 的实例）。”
public class TryDialogBox extends Application {
static Stage LOGIN_DIALOG;
static int dx = 1;
static int dy = 1;
private static Stage createLoginDialog(Stage parent, boolean modal) {
if (LOGIN_DIALOG != null) {
LOGIN_DIALOG.close();
}
return new MyDialog(parent, modal, "welcom");
}
public void start(final Stage stage) {
stage.setTitle("developing dialog");
Group root = new Group();
Scene scene = new Scene(root, 433, 312, Color.WHEAT);
MenuBar menuBar = new MenuBar();
menuBar.prefWidthProperty().bind(stage.widthProperty());
Menu menu = new Menu("home");
// add
MenuItem newItem = new MenuItem("change password", null);
newItem.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
if (LOGIN_DIALOG == null) {
LOGIN_DIALOG = createLoginDialog(stage, true);
}
LOGIN_DIALOG.sizeToScene();
LOGIN_DIALOG.show();
}
});
menu.getItems().add(newItem);
// add separator
menu.getItems().add(new SeparatorMenuItem());
// add non mdal menu item
ToggleGroup modalGroup = new ToggleGroup();
RadioMenuItem nonModalItem = RadioMenuItemBuilder.create()
.toggleGroup(modalGroup).text("non modal").selected(true)
.build();
nonModalItem.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
LOGIN_DIALOG = createLoginDialog(stage, false);
}
});
menu.getItems().add(nonModalItem);
// add modal
RadioMenuItem modalItem = RadioMenuItemBuilder.create()
.toggleGroup(modalGroup).text("modal").selected(true).build();
modalItem.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
LOGIN_DIALOG = createLoginDialog(stage, true);
}
});
menu.getItems().add(modalItem);
// add sep
menu.getItems().add(new SeparatorMenuItem());
// add exit
MenuItem exitItem = new MenuItem("Exit", null);
exitItem.setMnemonicParsing(true);
exitItem.setAccelerator(new KeyCodeCombination(KeyCode.X,
KeyCombination.CONTROL_DOWN));
exitItem.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
Platform.exit();
}
});
menu.getItems().add(exitItem);
// add menu
menuBar.getMenus().add(menu);
root.getChildren().add(menuBar);
stage.setScene(scene);
stage.show();
}
class MyDialog extends Stage {
public MyDialog(Stage owner, boolean modality, String title) {
super();
initOwner(owner);
Modality m = modality ? Modality.APPLICATION_MODAL : Modality.NONE;
initModality(m);
setOpacity(.90);
setTitle(title);
Group root = new Group();
Scene scene = new Scene(root, 250, 150, Color.WHITE);
setScene(scene);
GridPane gridpane = new GridPane();
gridpane.setPadding(new Insets(5));
gridpane.setHgap(5);
gridpane.setVgap(5);
Label mainLabel = new Label("enter username & password");
gridpane.add(mainLabel, 1, 0, 2, 1);
Label userNamelbl = new Label("username");
gridpane.add(userNamelbl, 0, 1);
Label passwordlbl = new Label("password");
gridpane.add(passwordlbl, 0, 2);
// username textfield
final TextField userNameFld = new TextField("Admin");
gridpane.add(userNameFld, 1, 1);
// password
final PasswordField passwordFld = new PasswordField();
passwordFld.setText("dwossap");
gridpane.add(passwordFld, 1, 2);
Button login = new Button("change");
login.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
close();
}
});
gridpane.add(login, 1, 3);
GridPane.setHalignment(login, HPos.RIGHT);
root.getChildren().add(gridpane);
}
}
public static void main(String[] args) {
launch(args);
}
}