JavaFX绘制单个轴

Question

如何将单个轴绘制到窗格？

如果我天真地尝试addAll(axis)，它会给我一个运行时异常

我正在浏览XYChart源代码，寻找关于它如何绘制轴的答案。

编辑：

来源

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.chart.NumberAxis;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class TestSingleAxis extends Application {


    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) {

        StackPane root = new StackPane();

        root.getChildren().addAll(new NumberAxis(1, 20, 1));

        Scene scene = new Scene(root, 1300, 800, Color.WHITESMOKE);
        stage.setScene(scene);
        stage.show();

    }

}

结果

Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:548)
    at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:48)
    at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:134)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.NullPointerException
    at javafx.scene.chart.Axis.layoutChildren(Axis.java:744)
    at javafx.scene.chart.ValueAxis.layoutChildren(ValueAxis.java:359)
    at javafx.scene.Parent.layout(Parent.java:1014)
    at javafx.scene.Parent.layout(Parent.java:1022)
    at javafx.scene.Scene.layoutDirtyRoots(Scene.java:537)
    at javafx.scene.Scene.doLayoutPass(Scene.java:508)
    at javafx.scene.Scene.preferredSize(Scene.java:1467)
    at javafx.scene.Scene.impl_preferredSize(Scene.java:1494)
    at javafx.stage.Window$10.invalidated(Window.java:720)
    at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:106)
    at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:140)
    at javafx.stage.Window.setShowing(Window.java:783)
    at javafx.stage.Window.show(Window.java:798)
    at javafx.stage.Stage.show(Stage.java:242)
    at guifx.TestSingleAxis.start(TestSingleAxis.java:32)
    at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:491)
    at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:260)
    at com.sun.javafx.application.PlatformImpl$5$1.run(PlatformImpl.java:223)
    at com.sun.javafx.application.PlatformImpl$5$1.run(PlatformImpl.java:220)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl$5.run(PlatformImpl.java:220)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)

Process finished with exit code 1

Answer 1

观察一些版本的代码，在744行附近，我看到：

    if (getSide().equals(Side.LEFT)) {

这段代码告诉我：

@Override
public void start(Stage primaryStage) {
    System.out.println(new NumberAxis(1, 2, 3).getSide());
}

>>null

看起来，无论如何你都需要指定侧边..

有帮助吗？