为什么Java没有在第二个场景上显示按钮

问题描述 投票:2回答:2

我的程序中有三个场景。当我开始它时,我看到所有按钮的第一个场景。然后,当我进入第二个场景时,我只看到标签,按钮没有显示出来。在第三个场景一切正常,我看到标签和按钮。

所以问题是,为什么我的按钮没有显示在我的第二个场景上?

我试图切换设置按钮和场景的顺序,使场景2(音量)是第三个场景,第三个场景(分辨率)是第二个场景。每次第二个场景都没有显示按钮。

package view.options;

import javafx.application.*;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Options extends Application {
    Scene optionsMenu, volumeMenu, resolutionMenu;

    // Create the labels
    Label optionslabel= new Label("This is the options scene");
    Label volumelabel= new Label("This is the volume scene");
    Label resolutionlabel= new Label("This is the resolution scene");
    Label labl_message = new Label("Volume settings");
    Label labl_generalvolume = new Label("General volume");
    Label labl_effectvolume = new Label("Effect volume");
    Label labl_musicvolume = new Label("Music volume");

    // Create the buttons
    Button optionsButton= new Button("Go to options");
    Button volumeButton= new Button("Go to volume settings");
    Button resolutionButton= new Button("Go to resolution settings");
    Button saveButton = new Button("save");
    Button exitButton = new Button("exit");

    // Create the sliders
    Slider slider_generalvolume;
    Slider slider_effectvolume;
    Slider slider_musicvolume;

    @Override
    public void start(Stage optionsStage) {
        // Setup the sliders
        slider_generalvolume = new Slider();
        slider_generalvolume.setMin(0);
        slider_generalvolume.setMax(100);
        slider_generalvolume.setValue(50);
        slider_generalvolume.setShowTickLabels(true);
        slider_generalvolume.setShowTickMarks(true);
        slider_generalvolume.setBlockIncrement(10);

        slider_effectvolume = new Slider();
        slider_effectvolume.setMin(0);
        slider_effectvolume.setMax(100);
        slider_effectvolume.setValue(50);
        slider_effectvolume.setShowTickLabels(true);
        slider_effectvolume.setShowTickMarks(true);
        slider_effectvolume.setBlockIncrement(10);

        slider_musicvolume = new Slider();
        slider_musicvolume.setMin(0);
        slider_musicvolume.setMax(100);
        slider_musicvolume.setValue(50);
        slider_musicvolume.setShowTickLabels(true);
        slider_musicvolume.setShowTickMarks(true);
        slider_musicvolume.setBlockIncrement(10);

        // Setup the main button
        optionsButton.setOnAction(e -> optionsStage.setScene(optionsMenu));
        volumeButton.setOnAction(e -> optionsStage.setScene(volumeMenu));
        resolutionButton.setOnAction(e -> optionsStage.setScene(resolutionMenu));
        exitButton.setOnAction(e -> Platform.exit());
        saveButton.setOnAction(e -> Platform.exit());

        // Setup the layout and add elements to it
        VBox optionsLayout = new VBox(20);
        optionsLayout.getChildren().addAll(optionslabel, volumeButton, resolutionButton, exitButton);
        optionsLayout.setStyle("-fx-padding: 10;" +
                "-fx-border-style: solid inside;" +
                "-fx-border-width: 2;" +
                "-fx-border-insets: 5;" +
                "-fx-border-radius: 5;" +
                "-fx-border-color: blue;");
        optionsMenu = new Scene(optionsLayout, 300, 250);

        VBox volumeLayout = new VBox(20);
        volumeLayout.getChildren().addAll(volumelabel, saveButton, optionsButton);
        volumeLayout.setStyle("-fx-padding: 10;" +
                "-fx-border-style: solid inside;" +
                "-fx-border-width: 2;" +
                "-fx-border-insets: 5;" +
                "-fx-border-radius: 5;" +
                "-fx-border-color: blue;");
        volumeMenu = new Scene(volumeLayout, 300, 250);

        VBox resolutionLayout = new VBox(20);
        resolutionLayout.getChildren().addAll(resolutionlabel, saveButton, optionsButton);
        resolutionLayout.setStyle("-fx-padding: 10;" +
                "-fx-border-style: solid inside;" +
                "-fx-border-width: 2;" +
                "-fx-border-insets: 5;" +
                "-fx-border-radius: 5;" +
                "-fx-border-color: blue;");
        resolutionMenu = new Scene(resolutionLayout, 300, 250);

        // Setup stage and start it
        optionsStage.setTitle("Options");
        optionsStage.setScene(optionsMenu);
        optionsStage.show();
    }

    public static void main(String[] args) {
        launch(args);
        System.out.println("exited successfully!");
    }
}

那该死的虫子在哪里?我不明白。它是某种Java或JavaFX伏都教,你看不到第二个场景的按钮?

java javafx
2个回答
3
投票

问题来自saveButton和来自optionButtonlayout.getChildren().addAll(..., saveButton, optionButton)。 Java FX节点最多限制为1个父节点,最多1个场景。尝试在多个位置使用它要么从旧父节点中删除它,要么导致异常。在您的情况下,旧父项将被删除并替换为新父项。要可视化问题,您可以更改布局初始化的顺序,因此,您将看到卷布局将起作用,而不是另一个。

因此,如果为每个布局创建saveButton和optionsButton的唯一实例,它将起作用。

例:

Button saveButtonVolume = new Button("save");
Button saveButtonResolution = new Button("save");

// ...

saveButtonVolume.setOnAction(e -> Platform.exit());
saveButtonResolution.setOnAction(e -> Platform.exit());

// ...

resolutionLayout.getChildren().addAll(resolutionlabel, saveButtonResolution, optionsButtonResolution);
volumeLayout.getChildren().addAll(volumelabel, saveButtonVolume, optionsButtonVolume);

遗憾的是,我没有找到任何方法来复制或克隆Java FX节点,这会简化问题(例如:saveButton.clone())。


1
投票

所以,这是一个只有一个场景,舞台和布局的工作示例。所有按钮都可以通过这种方式重复使用。这不是我通常喜欢的方式,但它的工作原理使代码更短。

package view.options;

import javafx.application.Application;
import javafx.application.Platform;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Options extends Application {
    // Create the labels
    Label optionslabel= new Label("This is the options scene");
    Label volumelabel= new Label("This is the volume scene");
    Label resolutionlabel= new Label("This is the resolution scene");
    Label labl_message = new Label("Volume settings");
    Label labl_generalvolume = new Label("General volume");
    Label labl_effectvolume = new Label("Effect volume");
    Label labl_musicvolume = new Label("Music volume");

    // Create the buttons
    Button optionsButton= new Button("Go to options");
    Button volumeButton= new Button("Go to volume settings");
    Button resolutionButton= new Button("Go to resolution settings");
    Button saveButton = new Button("save");
    Button exitButton = new Button("exit");

    VBox theOneAndOnlyLayout = new VBox(20);    
    Scene theOneAndOnlyScene;

    @Override
    public void start(Stage theOneAndOnlyStage) {
        theOneAndOnlyLayout.setStyle("-fx-padding: 10;" +
                "-fx-border-style: solid inside;" +
                "-fx-border-width: 2;" +
                "-fx-border-insets: 5;" +
                "-fx-border-radius: 5;" +
                "-fx-border-color: blue;");

        theOneAndOnlyScene = new Scene(theOneAndOnlyLayout, 300, 250);

        theOneAndOnlyLayout.getChildren().setAll(optionslabel, volumeButton, resolutionButton, exitButton);

        optionsButton.setOnAction(e -> {
            theOneAndOnlyStage.setTitle("Options");
            theOneAndOnlyLayout.getChildren().setAll(optionslabel, volumeButton, resolutionButton, exitButton);
        });
        volumeButton.setOnAction(e -> {
            theOneAndOnlyStage.setTitle("Volume");
            theOneAndOnlyLayout.getChildren().setAll(volumelabel, saveButton, optionsButton);
        });
        resolutionButton.setOnAction(e -> {
            theOneAndOnlyStage.setTitle("Resolution");
            theOneAndOnlyLayout.getChildren().setAll(resolutionlabel, saveButton, optionsButton);
        });
        exitButton.setOnAction(e -> Platform.exit());
        saveButton.setOnAction(e -> Platform.exit());

        // Setup stage and start it
        theOneAndOnlyStage.setTitle("Options");
        theOneAndOnlyStage.setScene(theOneAndOnlyScene);
        theOneAndOnlyStage.show();
    }

    public static void main(String[] args) {
        launch(args);
        System.out.println("exited successfully!");
    }
}
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