用javafx在代码中设置背景

Question

我正在尝试使用以下代码实现背景图像而不使用CSS，但它不适用于我。

下面是代码和错误

代码

Group root = new Group();
Scene scene = new Scene(root, 650, 1180); //1180, 650

String image = JavaFXApplication4.class.getClass().getResource("wallpaper4.jpg").toExternalForm();
root.setStyle("-fx-background-image: url('" + image + "'); -fx-background-repeat: stretch; -fx-background-size: 650 1180;-fx-background-position: top left;");

System.out.println("path: " + image);

stage.setScene(scene);

错误：

Caused by: java.lang.NullPointerException
    at javafxapplication4.JavaFXApplication4.start(JavaFXApplication4.java:381)
    at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:811)
    at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:295)
    at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:261)
    at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:258)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:258)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)

壁纸的位置

Answer 1

您的代码中存在错误。它应该是

String image = JavaFXApplication4.class.getResource("wallpaper4.jpg").toExternalForm();

Answer 2

＆＃39;根＆＃39;应该声明为StackPane。试试这个：

StackPane root = new StackPane()