Error: Could not find or load main class application.Main JAVAFX

问题

Under Java Build Path Libraries under the properties of my project, I have my User Library called javafx12 under Modulepath.

This removed all the errors regarding import javafx not resolved.

When I try to run my project, I get

"Error: Could not find or load main class application.Main Caused by: java.lang.NoClassDefFoundError: javafx/application/Application"

How do I get rid of this error?

I am using Java SE 12 aka JDK 12.

I am using eclipse as well.

    package application;

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.BorderPane;

public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            BorderPane root = new BorderPane();
            Scene scene = new Scene(root,400,400);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            primaryStage.setScene(scene);
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

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

No errors in the class file.

回答1:

Following @Ashish link openjfx.io/openjfx-docs

I did the following and it fixed the error:

Add VM arguments To solve the issue, click on Run -> Run Configurations... -> Java Application, create a new launch configuration for your project named hellofx and add these VM arguments:

Linux/Mac Windows

--module-path "\path\to\javafx-sdk-12.0.1\lib" --add-modules javafx.controls,javafx.fxml Warning: Make sure the option:

Use the -XstartOnFirstThread argument when launching with SWT is not selected. VM arguments Click apply and close the dialog.

回答2:

This worked for me after getting the error:

Could not find or load main class application.Main Caused by: java.lang.ClassNotFoundException: application.Main while trying to use JavaFX in Eclipse

Run then run configurations
In Main, choose the correct Project and Main class names
In Argument, enter this in VM arguments box: --module-path "\path\to\javafx-sdk-12.0.1\lib" --add-modules javafx.controls,javafx.fxml
Apply

回答3:

Hi, this is how I solved this problem.

Step #1:

Create new file "module-info.java" like in this picture: Project structure

Step #2

Content of the "module-info.java" file should look like this:

module Example {
    requires javafx.fxml;
    requires javafx.controls;

    opens application;
}

来源：https://stackoverflow.com/questions/56622327/error-could-not-find-or-load-main-class-application-main-javafx

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