javafx IllegalArgumentException(已设置为另一个场景的根) [英] javafx IllegalArgumentException (is already set as root of another scene)

问题描述

我在更改应用程序中的场景时遇到问题

I have problem with changing scenes in my application which looks like

Main screen > Login screen

我将屏幕存储为hashmap<String, Node>在主文件中，一切都很好，直到我从登录屏幕返回主屏幕并想再次加载登录屏幕，这是异常和代码:

I am storing screens in main file as hashmap<String, Node> and everything is good until I go back from login screen to main screen and want to load the login screen again, here is exception and code:

java.lang.IllegalArgumentException: AnchorPane@30561c33[styleClass=root]is already set as root of another scene

public static final HashMap<String, Parent> pages = new HashMap<>();

@FXML
private void LogIn(ActionEvent event) {
    Button button = (Button) event.getSource();
    Stage stage = (Stage) button.getScene().getWindow();
    if(stage.getScene() != null) {stage.setScene(null);}
    Parent root = MyApplication.pages.get("LoginPage");
    Scene scene = new Scene(root, button.getScene().getWidth(), button.getScene().getHeight());
    stage.setScene(scene);
}

当我创建新的锚定窗格时可以使用

It works when I'm creating new anchorpane

Parent root = new AnchorPane(MyApplication.pages.get("LoginPage"));

但是我想了解为什么如果我在同一舞台上工作会给我一个例外

But I want to understand why it gives me an exception if I'm working on the same stage

推荐答案

该异常是不言而喻的:锚窗格不能是两个不同场景的根.不必每次都创建一个新场景，只需替换现有场景的根:

The exception is pretty self-explanatory: the anchor pane cannot be the root of two different scenes. Instead of creating a new scene every time, just replace the root of the existing scene:

@FXML
private void LogIn(ActionEvent event) {
    Button button = (Button) event.getSource();
    Scene scene = button.getScene();
    Parent root = MyApplication.pages.get("LoginPage");
    scene.setRoot(root);
}

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