Question

我正处于计算机科学学习的第一年，而我刚得到的第一个项目是必须创建一个可以在SQL数据库上执行CRUD操作的应用程序。此应用程序需要具有一个GUI，我们需要为此使用JavaFX。

目前，我不确定如何处理按钮点击。例如，主屏幕上有三个按钮（“帐户”，“个人资料”，“已监视”），每个按钮都会创建一个带有三个按钮（“创建”，“编辑”，“删除”）的新场景。这导致许多lambda表达式彼此嵌套，这使代码看起来很混乱。在下面，您将看到我的代码的一部分：

public class GUI extends Application {

    Database db = new Database();

    @Override
    public void start(Stage stage) throws Exception {
        // Three buttons and a Label for the first scene.
        Button buttonAccounts = new Button("Accounts");
        Button buttonProfiles = new Button("Profiles");
        Button buttonWatched = new Button("Watched");
        Label pickAnOption = new Label("Pick an option:");

        // Two HBoxes, first one for the Label, the other one for the three Buttons.
        // Both HBoxes are aligned in the center.
        HBox options = new HBox(12);
        options.setAlignment(Pos.CENTER);
        options.getChildren().addAll(buttonAccounts, buttonProfiles, buttonWatched);
        HBox text = new HBox();
        text.setAlignment(Pos.CENTER);
        text.getChildren().add(pickAnOption);

        // The HBoxes are placed in a BorderPane.
        // HBox "text" has a top margin of 20 and HBox "options" has a bottom margin of 20.
        // This way, the BorderPane will be nicely aligned in the middle of the scene.
        BorderPane pane = new BorderPane();
        pane.setTop(text);
        pane.setMargin(text, new Insets(20, 0, 0 , 0));
        pane.setCenter(options);
        pane.setMargin(options, new Insets(0, 0, 20, 0));

        Scene selectionScreen = new Scene(pane, 500, 100);

        stage.setTitle("Netflix Statistix door S. Jaspers, I. Moerenhout en Z. Usmaeva");
        stage.setResizable(false);
        stage.setScene(selectionScreen);
        stage.show();

        // EventHandler for the Accounts Button.
        buttonAccounts.setOnAction(e -> {
            Button buttonCreateAccount = new Button("Create");
            Button buttonEditAccount = new Button("Edit");
            Button buttonDeleteAccount = new Button("Delete");
            Button back = new Button("Back");
            Label createEditOrDelete = new Label("Create a new account, or edit/delete an existing account:");

            back.setOnAction(e1 -> stage.setScene(selectionScreen));

            HBox text1 = new HBox();
            text1.setAlignment(Pos.CENTER);
            text1.getChildren().add(createEditOrDelete);
            HBox options1 = new HBox(12);
            options1.setAlignment(Pos.CENTER);
            options1.getChildren().addAll(buttonCreateAccount, buttonEditAccount, buttonDeleteAccount);
            HBox text2 = new HBox();
            text2.setSpacing(50);
            text2.getChildren().add(back);

            BorderPane pane1 = new BorderPane();
            pane1.setTop(text1);
            pane1.setMargin(text1, new Insets(15, 0, 0, 0));
            pane1.setCenter(options1);
            pane1.setMargin(options1, new Insets(0, 0, 15, 0));
            pane1.setBottom(text2);

            Scene accounts = new Scene(pane1, 500, 100);
            stage.setScene(accounts);

            // EventHandler for the Create Account button.
            buttonCreateAccount.setOnAction(e1 -> {
                GridPane grid = new GridPane();
                grid.setPadding(new Insets(10, 10, 10, 10));
                grid.setVgap(8);
                grid.setHgap(10);

                Button buttonSave = new Button("Save");
                Button buttonCancel = new Button("Cancel");

                buttonCancel.setOnAction(e3 -> {
                    stage.setScene(accounts);
                });

                Label accountName = new Label("Name:");
                Label accountAddress = new Label("Address:");
                Label accountCity = new Label("City:");

                TextField accountNameInput = new TextField();
                TextField accountAddressInput = new TextField();
                TextField accountCityInput = new TextField();

                grid.add(accountName, 0, 0);
                grid.add(accountNameInput, 1, 0);
                grid.add(accountAddress, 0, 1);
                grid.add(accountAddressInput, 1, 1);
                grid.add(accountCity, 0, 2);
                grid.add(accountCityInput, 1, 2);
                grid.add(buttonSave, 2, 3);
                grid.add(buttonCancel, 3, 3);

                Scene accountCreation = new Scene(grid);
                stage.setScene(accountCreation);

                buttonSave.setOnAction(e2 -> {
                    boolean succeeded = db.createAccount(accountNameInput.getText(), accountAddressInput.getText(), accountCityInput.getText());
                    if (succeeded) {
                        new Alert(Alert.AlertType.INFORMATION, "Account successfully created.").show();
                    } else {
                        new Alert(Alert.AlertType.WARNING, "Failed to create account.").show();
                    }
                });
            });

我对JavaFX还是很陌生，我想知道是否有任何方法可以使此代码更清晰。任何建议都非常感谢。

Answer 1

我想发表此评论，但我不能。您检查过FXML吗？它允许您以非常干净和简单的方式设置属性。如果您需要自动完成和检查，那么我建议使用IntelliJ IDEA。这是一篇很好的文章，解释了FXML的好处：https://docs.oracle.com/javafx/2/fxml_get_started/why_use_fxml.htm

Answer 2

您可以使您的GUI类实现EventHandler接口。然后，您可以在代码中编写以下内容：

buttonAccounts.setOnAction(this);

handle()方法的参数包含事件的来源，即单击的按钮。您的代码如下所示：

public class GUI extends Application implements EventHandler<Action> {
    public void handle(ActionEvent e) {
        Object source = e.getSource();
        if (source == buttonAccounts) {
            // Handle it.
        }
        else if (source == buttonEditAccount) {
        }
        // etc.
    }
}

您可以使用method references。编写一个使用单个ActionEvent参数并返回void的方法，例如

private void handleButtons(ActionEvent event) {
    Object source = event.getSource();
    // As above.
}

那你就可以写...

buttonAccounts.setOnAction(this::handleButtons);

有什么方法可以在我的JavaFX代码中提高清晰度？

2 个答案: