Java NoSuchMethodException – 类中确实存在方法

我正在构建一个JavaFx应用程序，我想创建一个接收GridPane和Node []的方法，其中包含添加到窗格的项目数量。 但是，当我调用该方法时，我得到一个NoSuchMethodException。

作为测试，我试图创建一个简单的方法private String helloWorld() ，它将return "Hello World"; 。 这个方法确实有效，但是当我尝试运行gridLogin = buildForm(gridLogin, items); ，我Exception in thread "main" java.lang.NoSuchMethodException错误中得到Exception in thread "main" java.lang.NoSuchMethodException 。

Application.java

 public class DesktopApplication extends Application { @Override public void start(Stage primaryStage) { BuildGraphicalUserInterface ui = new BuildGraphicalUserInterface(); ui.initStage(primaryStage); } } 

BuildGraphicalUserInterface.java

 package com.fenrir.desktop.UserInterface; import ...; public class BuildGraphicalUserInterface { private final String APP_TITLE = "Fenrir Desktop App"; private final String LOGIN_HEADER = "FENRIR secure"; Stage stage; Scene sceneLogin, sceneMain, sceneRegister; GridPane gridLogin, gridMain, gridRegister; long startTime, endTime; boolean authorized; Optional result; public void initStage(Stage primaryStage) { stage = primaryStage; // Set global ui options stage.setTitle(APP_TITLE); stage.setResizable(false); // Setup every screen in application initScenes(stage); } private void initScenes(Stage stage) { startTime = System.nanoTime(); sceneLogin = buildLoginScreen(); endTime = System.nanoTime(); System.out.println("login:\t" + (endTime - startTime)); startTime = System.nanoTime(); sceneMain = buildMainScreen(); endTime = System.nanoTime(); System.out.println("main:\t" + (endTime - startTime)); startTime = System.nanoTime(); sceneRegister = buildRegisterScreen(); endTime = System.nanoTime(); System.out.println("register:\t" + (endTime - startTime)); stage.setScene(sceneLogin); stage.show(); } // BUILD OF SCREENS private Scene buildLoginScreen() { gridLogin = new GridPane(); gridLogin.setAlignment(Pos.CENTER); gridLogin.setVgap(10); gridLogin.setHgap(10); Text loginTitle = new Text(LOGIN_HEADER); loginTitle.setFont(Font.font("Tahoma", FontWeight.NORMAL, 20)); Label usernameLabel = new Label("Username:"); final TextField usernameTextField = new TextField(); Label companyLabel = new Label("Company:"); final TextField companyTextField = new TextField(); Button loginButton = new Button("Login"); Hyperlink registerLink = new Hyperlink(); registerLink.setText("Register"); registerLink.setOnAction(new EventHandler() { public void handle(ActionEvent e) { stage.setScene(sceneRegister); } }); loginButton.setOnAction(new EventHandler() { public void handle(ActionEvent e) { UserAuthentication auth = new UserAuthentication(usernameTextField.getText(), companyTextField.getText()); try { // check if user exists auth.authenticate(); // show token pop up promptTokenAlert(); if (result.isPresent()) { if (auth.verifyToken(result.get())) { authorized = true; stage.setScene(sceneMain); } else wrongTokenAlert(); } } catch (IOException e1) { userNotFoundAlert(); usernameTextField.setText(""); companyTextField.setText(""); } }}); Node[] items = new Node[6]; items[0] = loginTitle; items[1] = usernameLabel; items[2] = usernameTextField; items[3] = companyLabel; items[4] = companyTextField; items[5] = loginButton; items[6] = registerLink; gridLogin = buildForm(gridLogin, items); sceneLogin = new Scene(gridLogin, 300, 200); return sceneLogin; } private Scene buildMainScreen() { gridMain = new GridPane(); final Label authorizedLabel = new Label("Authorized!"); Button logoutButton = new Button("Logout"); logoutButton.setOnAction(new EventHandler() { public void handle(ActionEvent e) { authorized = false; stage.setScene(sceneLogin); }}); gridMain.add(authorizedLabel, 0, 0); gridMain.add(logoutButton, 0, 1); sceneMain = new Scene(gridMain, 800, 600); return sceneMain; } private Scene buildRegisterScreen() { gridRegister = new GridPane(); gridRegister.setAlignment(Pos.CENTER); gridRegister.setVgap(10); gridRegister.setHgap(10); sceneRegister = new Scene(gridRegister, 300, 200); Label userName = new Label("Username:"); final TextField userTextField = new TextField(); Label company = new Label("Company:"); final TextField companyTextField = new TextField(); Label phoneNumber = new Label("Phone nr.:"); final TextField phoneNumberTextField = new TextField(); Button registerButton = new Button("Register"); Hyperlink returnLabel = new Hyperlink(); returnLabel.setText("Go back"); returnLabel.setOnAction(new EventHandler() { public void handle(ActionEvent e) { stage.setScene(sceneLogin); } }); registerButton.setOnAction(new EventHandler() { public void handle(ActionEvent event) { /** * register response * 1 - user already exists * 2 - incorrect username * 3 - incorrect phonenumber * 4 - unknown error * 0 - success */ int registerResponse; UserRegistration userReg = new UserRegistration(userTextField.getText(), companyTextField.getText(), phoneNumberTextField.getText()); try { registerResponse = userReg.Register(); } catch (IOException e) { registerResponse = 4; e.printStackTrace(); } if (registerResponse == 0) { userRegisteredConfirmation(); stage.setScene(sceneLogin); } else { userRegistrationErrorAlert(registerResponse); } } }); gridRegister.add(userName, 0, 1); gridRegister.add(userTextField, 1, 1); gridRegister.add(company, 0, 2); gridRegister.add(companyTextField, 1, 2); gridRegister.add(phoneNumber, 0, 3); gridRegister.add(phoneNumberTextField, 1, 3); gridRegister.add(registerButton, 1, 4); gridRegister.add(returnLabel, 0, 4); return sceneRegister; } /** * Builds a form with items received (items should be sorted) * @param grid * @param items * @return */ private GridPane buildForm(GridPane grid, Node[] items) { int row = 0; for (int i = 0; i < items.length; i++) { grid.add(items[i], i, row); if (i % 2 == 0) row++; } return grid; } // ALERTS /** * Alert is shown when service returns no user * @return */ private Alert userNotFoundAlert() { Alert alert = new Alert(Alert.AlertType.ERROR); alert.setTitle("FENRIR security"); alert.setHeaderText("Error"); alert.setContentText("User not recognized"); alert.showAndWait(); return alert; } /** * Alert is shown when user should enter token * @return */ private TextInputDialog promptTokenAlert() { TextInputDialog alert = new TextInputDialog(""); alert.setTitle("FENRIR security"); alert.setHeaderText("Token requested"); result = alert.showAndWait(); return alert; } /** * Alert is shown when entered token is wrong * @return */ private Alert wrongTokenAlert() { Alert alert = new Alert(Alert.AlertType.ERROR); alert.setTitle("FENRIR security"); alert.setHeaderText("Token incorrect"); alert.showAndWait(); return alert; } /** * Confirmation is shown when registration is completed * @return */ private Alert userRegisteredConfirmation() { Alert alert = new Alert(Alert.AlertType.INFORMATION); alert.setTitle("FENRIR security"); alert.setHeaderText("Success"); alert.setContentText("Registration completed"); alert.showAndWait(); return alert; } /** * Alert is shown when an error occurs during registration * @param errorCode * @return */ private Alert userRegistrationErrorAlert(int errorCode) { Alert alert = new Alert(Alert.AlertType.ERROR); alert.setTitle("FENRIR security"); alert.setHeaderText("Error"); String errorMessage; switch (errorCode) { case 1: errorMessage = "User already exists."; break; case 2: errorMessage = "Incorrect username. Username should be at least 2 characters."; break; case 3: errorMessage = "Incorrect phone number. Should be 8 characters and only numbers."; break; default: errorMessage = "Unknown error. Contact administrator."; } alert.setContentText(errorMessage); alert.showAndWait(); return alert; } } 

堆栈跟踪

 Exception in Application start method Exception in thread "main" java.lang.NoSuchMethodException: com.fenrir.desktop.DesktopApplication.main([Ljava.lang.String;) at java.lang.Class.getMethod(Class.java:1786) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:125) Process finished with exit code 1 

Answer 1

这将解决你的问题，安装e（fx）clipse这个插件为eclise，但我不知道intellij，或为你的应用程序添加facet作为javafx应用程序，如果你添加facet你不需要main方法，或使用像这样

 public class DesktopApplication extends Application { @Override public void start(Stage primaryStage) { BuildGraphicalUserInterface ui = new BuildGraphicalUserInterface(); ui.initStage(primaryStage); } public static void main(String[] args) { launch(args); } }