Topics in Part 2

• Creating a model class
• Using the model class in an ObservableList
• Show data in the TableView using Controllers

Create the Model Class

We need a model class to hold information about the people in our address book. Add a new class to the model package (ch.makery.address.model) called Person. This makes sense, since we want to manage people and their addresses. The Person class will have a few instance variables for the name, address and birthday. Add the following code to the class:

Person.java

package ch.makery.address.model;

import java.util.Calendar;

/**
 * Model class for a Person.
 *
 * @author Marco Jakob
 */
public class Person {

    private String firstName;
    private String lastName;
    private String street;
    private int postalCode;
    private String city;
    private Calendar birthday;

    /**
     * Default constructor.
     */
    public Person() {
    }

    /**
     * Constructor with some initial data.
     * 
     * @param firstName
     * @param lastName
     */
    public Person(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;

        // some initial dummy data
        this.street = "some street";
        this.postalCode = 1234;
        this.city = "some city";
        this.birthday = Calendar.getInstance();
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }

    public int getPostalCode() {
        return postalCode;
    }

    public void setPostalCode(int postalCode) {
        this.postalCode = postalCode;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public Calendar getBirthday() {
        return birthday;
    }

    public void setBirthday(Calendar birthday) {
        this.birthday = birthday;
    }
}

A List of Persons

The main Data that our application manages is a bunch of persons. Let's create a list for Person objects inside the MainApp class. All other controller classes will later get access to the list inside the MainApp.

ObservableList

We are working with JavaFX view classes that always need to be informed about any changes made to the list of persons. This is important, since otherwise the view would not be in sync with the data. For this purpose, JavaFX introduces some new Collection classes.

From those collections, we need the ObservableList. To create a new ObservableList, add the following code at the beginning of the MainApp class. We'll also add a constructor that creates some sample data and a public getter method:

MainApp.java

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;

  // ...

    /**
     * The data as an observable list of Persons.
     */
    private ObservableList<Person> personData = FXCollections.observableArrayList();

    /**
     * Constructor
     */
    public MainApp() {
        // Add some sample data
        personData.add(new Person("Hans", "Muster"));
        personData.add(new Person("Ruth", "Mueller"));
        personData.add(new Person("Heinz", "Kurz"));
        personData.add(new Person("Cornelia", "Meier"));
        personData.add(new Person("Werner", "Meyer"));
        personData.add(new Person("Lydia", "Kunz"));
        personData.add(new Person("Anna", "Best"));
        personData.add(new Person("Stefan", "Meier"));
        personData.add(new Person("Martin", "Mueller"));
    }

    /**
     * Returns the data as an observable list of Persons. 
     * @return
     */
    public ObservableList<Person> getPersonData() {
        return personData;
    }

// ...

The PersonOverviewController

Now let's finally view some data in our table.

1. Create a normal class inside the controller package called PersonOverviewController.java.
2. We'll add some instance variables that give us access to the table and the labels inside the view. The fields and some methods have a special @FXML annotation. This is necessary for the fxml file to have access to those variables. After we have everything set up in the fxml file, the application will automatically fill the variables when the fxml file is loaded. So let's add the following code:

Note: Remember to always use the javafx imports (not awt or swing)!

PersonOverviewController.java

public class PersonOverviewController {
    @FXML
    private TableView<Person> personTable;
    @FXML
    private TableColumn<Person, String> firstNameColumn;
    @FXML
    private TableColumn<Person, String> lastNameColumn;

    @FXML
    private Label firstNameLabel;
    @FXML
    private Label lastNameLabel;
    @FXML
    private Label streetLabel;
    @FXML
    private Label postalCodeLabel;
    @FXML
    private Label cityLabel;
    @FXML
    private Label birthdayLabel;

    // Reference to the main application
    private MainApp mainApp;

    /**
     * The constructor.
     * The constructor is called before the initialize() method.
     */
    public PersonOverviewController() {
    }

    /**
     * Initializes the controller class. This method is automatically called
     * after the fxml file has been loaded.
     */
    @FXML
    private void initialize() {
    // Initialize the person table
        firstNameColumn.setCellValueFactory(new PropertyValueFactory<Person, String>("firstName"));
        lastNameColumn.setCellValueFactory(new PropertyValueFactory<Person, String>("lastName"));
    }

    /**
     * Is called by the main application to give a reference back to itself.
     * 
     * @param mainApp
     */
    public void setMainApp(MainApp mainApp) {
        this.mainApp = mainApp;

        // Add observable list data to the table
        personTable.setItems(mainApp.getPersonData());
    }
}

Now this code will need some explanation:

• All fields and methods where the fxml file needs access must be annotated with @FXML. Actually, only if they are private, but it's better to have them private and mark them with the annotation!.
• The initialize() method is automatically called after the fxml file has been loaded. At this time, all the FXML fields should have been initialized already.
• The PropertyValueFactory that we set on the table colums are used to determine which field inside the Person objects should be used for the particular column.
• The setMainApp(...) method must be called by the MainApp class. This gives us a way to access the MainApp object and get the list of data and other things. In fact, let's do that call right now. Replace the showPersonOverview() method with the following. It contains two additional lines:

MainApp.java

/**
 * Shows the person overview scene.
 */
public void showPersonOverview() {
    try {
        // Load the fxml file and set into the center of the main layout
        FXMLLoader loader = new FXMLLoader(MainApp.class.getResource("view/PersonOverview.fxml"));
        AnchorPane overviewPage = (AnchorPane) loader.load();
        rootLayout.setCenter(overviewPage);

        // Give the controller access to the main app
        PersonOverviewController controller = loader.getController();
        controller.setMainApp(this);

    } catch (IOException e) {
        // Exception gets thrown if the fxml file could not be loaded
        e.printStackTrace();
    }
}

Hook the View to the Controller

We're almost there! But one little thing is missing: We haven't told our PersonOverview.fxml file yet, which controller to use and which element should match to which field inside the controller.

1. Open PersonOverview.fxml with the Scene Builder.
2. Select the topmost AnchorPane in the Hierarchy.

3. Open Code on the right side and select the PersonOverviewController as controller class.
   

4. Select the TableView and choose under Properties the personTable field as fx:id.
   

5. Do the same for the columns and select firstNameColumn and lastNameColumn respectively.

6. For each label in the second column, choose the corresponding fx:id.
7. Important: Go back to Eclipse and refresh the entire AddressApp project (F5). This is necessary because Eclipse sometimes doesn't know about changes that were made inside the Scene Builder.

Start the Application

When you start your application now, you should see something like the screenshot at the beginning of this blog post.

Congratulations!

What's Next?

In Tutorial Part 3 we will add more functionality like adding, deleting and editing Persons.