Question

我尝试用FXML制作一个应用程序。一开始我有一个舞台有2个场景，当我按下按钮时场景应该会改变当我按下按钮时，出现此错误：

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
    at application.Controller.lambda$0(Controller.java:43)

这是我的控制器类：

public class Controller{

public Stage primaryStage;
@FXML
private Button button;

public void plm(Stage primaryStage){
    try {
        System.out.println(primaryStage);
        BorderPane root = (BorderPane)FXMLLoader.load(getClass().getResource("Sample.fxml"));
        Scene scene = new Scene(root,400,400);
        //scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
        primaryStage.setScene(scene);
        primaryStage.show();
        this.primaryStage = primaryStage;
        System.out.println(this.primaryStage);
    } catch(Exception e) {
        e.printStackTrace();
    }
}

@FXML
public void cc() throws IOException{
    Parent root = FXMLLoader.load(getClass().getResource("SampleB.fxml"));
    Scene scene = new Scene(root,400,400);
    primaryStage.setScene(scene);

//  primaryStage.close();
}

这是我的FXML文件：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.BorderPane?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.Controller">
   <center>
      <Button fx:id="button" mnemonicParsing="false" onAction="#cc" text="Button" BorderPane.alignment="CENTER" />
   </center>
</BorderPane>

尝试在场景之间切换时，按钮在FXML中不起作用

0 个答案: