Module 3: Displaying data

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In this post, I provide accurate answers and detailed explanations for Module 3: Displaying data of Course 4: Database Management with Java and SQL – Amazon Junior Software Developer Professional Certificate.

Whether you’re preparing for quizzes or brushing up on your knowledge, these insights will help you master the concepts effectively. Let’s dive into the correct answers and detailed explanations for each question.

Knowledge check: Java user interface

Practice Assignment

1. What is the main class that you must extend to create a JavaFX application?

  • Application
  • SwingApplication
  • FXWindow
  • JFrame 

Explanation: In JavaFX, you create a JavaFX application by extending the Application class and overriding its start(Stage primaryStage) method.

2. True or False: JavaFX applications use an event-driven programming model.

  • True
  • False

Explanation: JavaFX applications are event-driven, meaning user actions like mouse clicks and key presses trigger events that the application responds to.

3. Which method is typically used to launch a JavaFX application?

  • startStage()
  • launch()
  • run()
  • startApplication()

Explanation: The launch() method is a static method provided by the Application class to start a JavaFX application.

4. You're developing a JavaFX application where you need to separate the user interface layout from the application logic to make the design more manageable. Which file format should you use?

  • CSS
  • JSON
  • FXML
  • HTML

Explanation: FXML is an XML-based file format used in JavaFX to define the user interface, allowing you to separate UI design from application logic.

5. Which of the following statement(s) about JavaFX is true?

  • JavaFX can be styled using CSS
  • JavaFX completely replaces Swing
  • JavaFX does not support multimedia
  • JavaFX does not support 3D graphics

Explanation: JavaFX supports styling using CSS, enabling developers to customize the appearance of UI components. The other statements are incorrect:

  • JavaFX does not completely replace Swing but is an alternative.
  • JavaFX supports multimedia and 3D graphics.

Knowledge check: Connecting JavaFX application to a database

Practice Assignment

6. What is the correct approach to retrieving and displaying data from a database in a TextArea in a JavaFX application?

  • Retrieve the data in the JavaFX class constructor and immediately set the results in the TextArea.
  • Use a Label instead of a TextArea to display the retrieved data from the database.
  • Execute a database query in a separate method from a dedicated class and set the results in the TextArea.
  • Directly execute the database query in the UI class and set the results in the TextArea. 

Explanation:
This approach follows the principle of separation of concerns. Database logic should be handled in a separate class or method, and the results can then be passed to the UI for display. This enhances maintainability and readability.

7. In your JavaFX application, you must display a list of User objects, where each User has properties like name and email, retrieved from a database. Which component would you use to do this?

  •  TableView
  • ListView
  • ComboBox
  • TextArea 

Explanation:
A TableView is suitable for displaying tabular data where rows represent objects (e.g., User), and columns represent object properties (e.g., name, email).

8. In your JavaFX application, an SQLException occurs due to an invalid database connection while retrieving a list of books. How would you handle this to prevent the app from crashing and inform the user?

  •  Let the application crash and print the stack trace for debugging.
  • Catch the SQLException and display a user-friendly error message in a Label on the UI.
  • Ignore the exception and continue with the following operation.
  • Log the exception to the console and show no message to the user.

Explanation:
This approach ensures the app does not crash and provides a user-friendly experience by informing the user of the issue.

9. True or False: A TableView in JavaFX is used to display data in a tabular format, where each row represents an object and each column corresponds to a property of that object.

  • True
  • False

Explanation:
TableView is specifically designed for this purpose, allowing developers to bind object properties to table columns.

10. What are the steps to display a list of User objects in a TableView in a JavaFX application? Select all that apply.

  • Populate the TableView with data using the setItems() method.
  • Create a TableView<User> object.
  • Set up columns for each property of the User object in the TableView.
  • Bind the getAllUsers() method directly to the TableView .

Explanation:

  1. A TableView object is created to display the data.
  2. Columns are configured to map to the properties of the User object.
  3. The setItems() method is used to populate the TableView with data (e.g., an ObservableList of User objects).

Knowledge check: Connecting JavaFX application to a database

Practice Assignment

11. You design the JavaFX application user interface using SceneBuilder, which generates a file with an FXML extension. This file contains:

  • XML script
  • HTML script
  • Java code
  • CSS script  

Explanation:
FXML is an XML-based file format used in JavaFX to define the structure of the user interface.

12. True or False: In a JavaFX application, GridPane is the best and most efficient control for displaying data from a dynamic Users table of a database.

  • False
  • True

Explanation:
While GridPane is useful for layout design, TableView is specifically designed for displaying tabular data dynamically from a database.

13. Which of the following UI elements can be used as a top-level JavaFX container? Select all that apply.

  • AnchorPane
  • VBox
  • TableView
  • BorderPane

Explanation:
These are layout containers in JavaFX that can act as root elements for a Scene. TableView is a control, not a container.

14. Complete the statement: What is a Property in JavaFX? It is ...

  • a section in the Library pane of SceneBuilder.
  • a type of control in JavaFX.
  • a getter method in a Controller class.
  • an observable object.

Explanation:
Properties in JavaFX are observable objects that allow binding and listening to changes, which is essential for reactive programming.

15. Where is the initialize() method defined in a JavaFX project?

  • Application class
  • FXML file
  • CSS file
  • Controller class 

Explanation:
The initialize() method is part of the Initializable interface and is typically implemented in the controller class to perform setup tasks when the FXML file is loaded.

Module quiz: Displaying data

Practice Assignment

16. Which of the following are features of JavaFX? Select all that apply.

  • Provides tools for building interactive applications.
  • Offers CSS-like styling and FXML support.
  • Designed primarily for writing backend Java applications.
  • Handles database queries.

Explanation:
JavaFX is designed for building rich user interfaces with interactive features. It supports CSS styling and FXML for separating design from logic. It is not designed for backend applications or directly handling database queries.

17. Which of the following are use cases for JavaFX? Select all that apply.

  • Handling file system operations.
  • Creating user input forms.
  • Displaying data in a table.
  • Managing databases.

Explanation:
JavaFX excels in creating user interfaces, including input forms and tables. It doesn’t handle file system operations or database management directly, though these can be integrated using other Java libraries.

18. What makes VSCode popular among developers? Select all that apply.

  • It is open-source and lightweight.
  • It only runs on Windows.
  • It has a wide range of extensions.
  • It doesn’t support plugins. 

Explanation:
VSCode is popular because of its open-source nature, lightweight design, and extensibility through plugins and extensions. It runs on multiple platforms, not just Windows.

19. What are some of the tasks Maven helps within Java projects? Select all that apply.

  • Writing business logic
  • Managing dependencies
  • Building the project
  • Styling UI with CSS

Explanation:
Maven is a build automation tool that helps manage project dependencies and automates the build process. It doesn’t handle writing business logic or UI styling.

20. In JavaFX, which of the following methods are involved in initializing the primary view and setting the scene?

  • getPrimaryButtonHandler()
  • start(Stage stage)
  • renderGUIComponents(Stage stage)
  • setRoot(String view)  

Explanation:
The start(Stage stage) method is the entry point for setting up the primary view and scene in a JavaFX application. Other methods may assist but are not required for scene initialization.

21. What is SceneBuilder used for in JavaFX development?

  • SceneBuilder generates Java code instead of FXML for user interface design.
  • SceneBuilder automatically handles all JavaFX database connections.
  • SceneBuilder is a code editor for writing JavaFX event handlers.
  • SceneBuilder is a drag-and-drop tool for designing JavaFX user interfaces without directly writing code. 

Explanation:
SceneBuilder simplifies the design process by allowing developers to create UI layouts visually and generates FXML files.

22. The following code defines a VBox layout with a label for entering a name, a text field for input, and a button that triggers an action. In which file will this FXML code be saved after designing a JavaFX UI in SceneBuilder?

  • mainscene.fxml
  • PrimaryController.java
  • App.java
  • pom.xml

Explanation:
FXML files store the UI structure designed in SceneBuilder. The file name often corresponds to the main scene or layout, such as mainscene.fxml.

23. What does the fx:id property in FXML represent?

  • It assigns a unique identifier to a UI component so that it can be referenced in the controller.
  • It specifies the layout of the component within the FXML file.
  • It determines the style of the UI component in FXML.
  • It defines the event handlers for a component in FXML.

Explanation:
The fx:id property links UI components in the FXML file to variables in the controller class for event handling or data manipulation.

24. What is the purpose of property binding in JavaFX?

  • It allows properties to automatically update when the value of a related property changes.
  • It disables UI components when a property changes.
  • It allows properties to store multiple values at once.
  • It prevents any modifications to the bound properties.

Explanation:
Property binding ensures synchronization between UI components and data models, enabling dynamic updates in the application.

25. You are initializing a TableView in JavaFX to display User objects with columns for Name and Age. The TableColumn objects are correctly set up using PropertyValueFactory to bind to the User properties.

How do you add the columns to the TableView?

  • tableView.setColumns(nameCol, ageCol);
  • tableView.getColumns().addAll(nameCol, ageCol);
  • tableView.addColumns(nameCol, ageCol);
  • tableView.setColumns().addAll(nameCol, ageCol);

Explanation:
The getColumns().addAll() method adds columns to a TableView in JavaFX. This method is used to populate the TableView with multiple TableColumn objects.

Related contents:

Module 1: Introduction to databases
Module 2: Databases and Java
Module 4: Final project and assessment: Data structures and algorithms

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Course 2: Programming with Java
Course 3: Data Structures and Algorithms
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Course 7: Application Development

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