JavaFX FXML应用程序将无法运行

时间:2018-10-13 21:04:32

标签: java eclipse javafx java-8 fxml

我正在尝试遵循教程here。但是,我的IDE(Eclipse)似乎不想使用它。我尝试将代码示例复制并粘贴到我的IDE中,但是会弹出相同的错误。不幸的是,没有显示任何窗口。

请帮助我弄清楚这段代码有什么问题。

错误:

 Exception in Application start method
    java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
        at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
    Caused by: java.lang.RuntimeException: Exception in Application start method
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$154(LauncherImpl.java:182)
        at java.lang.Thread.run(Thread.java:748)
    Caused by: java.lang.NullPointerException: Location is required.
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3207)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
        at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
        at application.RegistrationFormApplication.start(RegistrationFormApplication.java:13)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
        at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
        at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
        at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
        at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139)
        ... 1 more
    Exception running application application.RegistrationFormApplication

主类:

package application;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class RegistrationFormApplication extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("registration_form.fxml"));
        primaryStage.setTitle("Registration Form FXML Application");
        primaryStage.setScene(new Scene(root, 800, 500));
        primaryStage.show();
    }


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

FXML文档:

<?import javafx.scene.layout.GridPane?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.control.PasswordField?>
<?import javafx.scene.control.Button?>

<GridPane fx:controller="javafx.example.RegistrationFormController"
          xmlns:fx="http://javafx.com/fxml" alignment="center"
          hgap="10" vgap="10">
    <padding><Insets top="40" right="40" bottom="40" left="40"/></padding>
    <columnConstraints>
        <ColumnConstraints minWidth="100" prefWidth="100"
                           maxWidth="Infinity" halignment="RIGHT">
        </ColumnConstraints>
        <ColumnConstraints minWidth="200" prefWidth="200"
                           maxWidth="Infinity" hgrow="ALWAYS">
        </ColumnConstraints>
    </columnConstraints>

    <!-- Add Header Label -->
    <Label text="Registration Form (FXML)" GridPane.columnIndex="0" 
           GridPane.rowIndex="0" GridPane.columnSpan="2" 
           GridPane.rowSpan="1" GridPane.halignment="CENTER" >
        <font>
            <Font name="Arial" size="24" ></Font>
        </font>
        <GridPane.margin>
            <Insets top="20" right="0" bottom="20" left="0"></Insets>
        </GridPane.margin>
    </Label>



    <!-- Add Name Label -->
    <Label text="Full Name : " GridPane.columnIndex="0" 
           GridPane.rowIndex="1" >
    </Label>
    <!-- Add Name Text Field -->
    <TextField fx:id="nameField" prefHeight="40" 
               GridPane.columnIndex="1" GridPane.rowIndex="1"/>


    <!-- Add Email Label -->
    <Label text="Email ID : " GridPane.columnIndex="0" 
           GridPane.rowIndex="2" >
    </Label>
    <!-- Add Email Text Field -->
    <TextField fx:id="emailField" prefHeight="40" 
               GridPane.columnIndex="1" GridPane.rowIndex="2"/>



    <!-- Add Password Label -->
    <Label text="Password : " GridPane.columnIndex="0" 
           GridPane.rowIndex="3" >
    </Label>
    <!-- Add Password Field -->
    <PasswordField fx:id="passwordField" prefHeight="40" 
                   GridPane.columnIndex="1" GridPane.rowIndex="3"/>


    <!-- Add Submit Button -->
    <Button fx:id="submitButton" text="Submit"
            prefWidth="100" prefHeight="40" defaultButton="true"
            GridPane.columnIndex="0" GridPane.rowIndex="4"
            GridPane.columnSpan="2" GridPane.rowSpan="1"
            GridPane.halignment="CENTER"
            onAction="#handleSubmitButtonAction">
        <GridPane.margin>
            <Insets top="20" right="0" bottom="20" left="0"></Insets>
        </GridPane.margin>
    </Button>
</GridPane>

使用FXML文档的类:

package application;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.stage.Window;

public class RegistrationFormController {
    @FXML
    private TextField nameField;

    @FXML
    private TextField emailField;

    @FXML
    private PasswordField passwordField;

    @FXML
    private Button submitButton;

    @FXML
    protected void handleSubmitButtonAction(ActionEvent event) {
        Window owner = submitButton.getScene().getWindow();
        if(nameField.getText().isEmpty()) {
            AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Form Error!", 
                    "Please enter your name");
            return;
        }
        if(emailField.getText().isEmpty()) {
            AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Form Error!", 
                    "Please enter your email id");
            return;
        }
        if(passwordField.getText().isEmpty()) {
            AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Form Error!", 
                    "Please enter a password");
            return;
        }

        AlertHelper.showAlert(Alert.AlertType.CONFIRMATION, owner, "Registration Successful!", 
                "Welcome " + nameField.getText());
    }
}

AlertHelper类(在上述类中调用):

package application;

import javafx.scene.control.Alert;
import javafx.stage.Window;

public class AlertHelper {

    public static void showAlert(Alert.AlertType alertType, Window owner, String title, String message) {
        Alert alert = new Alert(alertType);
        alert.setTitle(title);
        alert.setHeaderText(null);
        alert.setContentText(message);
        alert.initOwner(owner);
        alert.show();
    }
}

1 个答案:

答案 0 :(得分:0)

我有两个问题导致程序无法正确显示。

首先,一行

Parent root = FXMLLoader.load(getClass().getResource("registration_form.fxml"));

应该已经

Parent root = FXMLLoader.load(getClass().getResource("/registration_form.fxml"));

此外,我的图形驱动程序已过时。

由于我的操作系统是Ubuntu 18.04,因此更新它们的过程如下。

首先,我打开程序“ Ubuntu Software”,单击屏幕右上角的“软件和更新”,然后在弹出的窗口中单击选项卡“其他驱动程序”。

然后,我选择“来自nvidia-driver-410的NVIDIA驱动程序元软件包”,然后单击“应用更改”。

enter image description here

这解决了我的问题,并允许程序正确显示。