import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;
import javafx.stage.Stage;
import javafx.scene.control.ButtonType;
import javafx.scene.control.Dialog;

public class web extends Application {

    static String url;

    @Override
    public void start(Stage primaryStage) throws Exception {
        WebView webView = new WebView();
        WebEngine engine = webView.getEngine();
        engine.setOnAlert(event -> showAlert(event.getData()));
        engine.load(url);

        Scene scene = new Scene(webView, 800, 600);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        url = args[0];
        System.out.println("URL="+url);
        launch(args);
    }
    private void showAlert(String message) {
        Dialog<Void> alert = new Dialog<>();
        alert.getDialogPane().setContentText(message);
        alert.getDialogPane().getButtonTypes().add(ButtonType.OK);
        alert.showAndWait();
    }
}