JavaFx 9 tutorial - Part 2: Model and TableView
Introduction
In this tutorial, we will create the other parts of the application (mainly the model and the controller). We will also use ObservableList
and *Property
to bind our list of new model's Person
s, and their individual details, to the view, with the controller as the "middleman".
Create the Model class
We need a model class in order to hold information about the people in our address book. Add a new class to the model
package (seedu.address.model
) called Person
. The Person
class will encapsulate the details of an individual person such as name, address and birthday. Add the following code to the class. The JavaFX specifics will be explained after the code snippet.
Person.java
package seedu.address.model;
import java.time.LocalDate;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
public class Person {
private final StringProperty firstName;
private final StringProperty lastName;
private final StringProperty street;
private final IntegerProperty postalCode;
private final StringProperty city;
private final ObjectProperty< LocalDate > birthday;
public Person() {
this(null, null);
}
public Person(String firstName, String lastName) {
this.firstName = new SimpleStringProperty(firstName);
this.lastName = new SimpleStringProperty(lastName);
this.street = new SimpleStringProperty("some street");
this.postalCode = new SimpleIntegerProperty(1234);
this.city = new SimpleStringProperty("some city");
this.birthday = new SimpleObjectProperty< LocalDate >(LocalDate.of(1999, 2, 21));
}
public String getFirstName() {
return firstName.get();
}
public void setFirstName(String firstName) {
this.firstName.set(firstName);
}
public StringProperty firstNameProperty() {
return firstName;
}
public String getLastName() {
return lastName.get();
}
public void setLastName(String lastName) {
this.lastName.set(lastName);
}
public StringProperty lastNameProperty() {
return lastName;
}
public String getStreet() {
return street.get();
}
public void setStreet(String street) {
this.street.set(street);
}
public StringProperty streetProperty() {
return street;
}
public int getPostalCode() {
return postalCode.get();
}
public void setPostalCode(int postalCode) {
this.postalCode.set(postalCode);
}
public IntegerProperty postalCodeProperty() {
return postalCode;
}
public String getCity() {
return city.get();
}
public void setCity(String city) {
this.city.set(city);
}
public StringProperty cityProperty() {
return city;
}
public LocalDate getBirthday() {
return birthday.get();
}
public void setBirthday(LocalDate birthday) {
this.birthday.set(birthday);
}
public ObjectProperty< LocalDate > birthdayProperty() {
return birthday;
}
}
Explanations
- With JavaFX, it is common to use
*Property
for all fields of a model class. A Property
allows us, for example, to automatically be notified when the lastName
or any other variable is changed. This helps us keep the view in sync with the data.
- To learn more about
*Property
, refer to Using JavaFX Properties and Binding
LocalDate
, the type that we are using for birthday
, is part of the new Date and Time API since JDK 8
A List of Persons
The main data that our application manages is simply a bunch of persons. Let's create a list of Person
objects inside the MainApp
class. All other controller classes will later get access to that central list inside the MainApp
.
ObservableList
We are working with JavaFX view classes that 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.
Among all these 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
private ObservableList< Person > personData = FXCollections.observableArrayList();
public MainApp() {
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"));
}
public ObservableList< Person > getPersonData() {
return personData;
}
The PersonOverviewController
We have our model and view. Let's get our data into our table. We'll need a controller for our PersonOverview.fxml
to act as a "middleman" for the model and view.
Create a normal Java class inside the view
package called PersonOverviewController
.
Note: We must put the class inside the same package as PersonOverview.fxml
, otherwise the SceneBuilder won't be able to find it.
We will 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 in order for the .fxml
file to have access to private fields and private methods. 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
package seedu.address.view;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import seedu.address.MainApp;
import seedu.address.model.Person;
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;
private MainApp mainApp;
public PersonOverviewController() {
}
@FXML
private void initialize() {
firstNameColumn.setCellValueFactory(cellData -> cellData.getValue().firstNameProperty());
lastNameColumn.setCellValueFactory(cellData -> cellData.getValue().lastNameProperty());
}
public void setMainApp(MainApp mainApp) {
this.mainApp = mainApp;
personTable.setItems(mainApp.getPersonData());
}
}
Explanations
- 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
setCellValueFactory(...)
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 arrow ->
indicates that we're using a Java 8 feature called Lambdas. (Another option would be to use a PropertyValueFactory
, but this is not type-safe).
Note:
We're only using StringProperty
values for our table columns in this example. When you want to use IntegerProperty
or DoubleProperty
, the setCellValueFactory(...)
must have an additional asObject()
:
myIntegerColumn.setCellValueFactory(cellData ->
cellData.getValue().myIntegerProperty().asObject());
This is necessary because of a bad design decision of JavaFX (see this discussion for more details).
Connecting MainApp with the PersonOverviewController
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 Persons
and other things. Add the following three lines to showPersonOverview()
the method:
MainApp.java - additional lines to add to showPersonOverview() method
PersonOverviewController controller = loader.getController();
controller.setMainApp(this);
Your showPersonOverview()
method in MainApp
should now look like this:
MainApp.java - new showPersonOverview() method
public void showPersonOverview() {
try {
FXMLLoader loader = new FXMLLoader();
loader.setLocation(MainApp.class.getResource("view/PersonOverview.fxml"));
AnchorPane personOverview = loader.load();
rootLayout.setCenter(personOverview);
PersonOverviewController controller = loader.getController();
controller.setMainApp(this);
} catch (IOException e) {
e.printStackTrace();
}
}
Hook the View to the controller
We're almost there! But one thing is missing: We haven't told our PersonOverview.fxml
file which controller to use, and which element should match to which field inside the controller.
- Open
PersonOverview.fxml
with the SceneBuilder.
- Open the Controller group on the left side (just below Hierarchy), and select the
seedu.address.view.PersonOverviewController
as the controller class.
- Select the
TableView
in the Hierarchy group.
- In the Inspector view, under the Code group, set 'fx:id' to
personTable
.
- Do the same for the table columns. Select
firstNameColumn
and lastNameColumn
for the 'fx:id' respectively.
- For each label in the second column of the grid pane, choose the corresponding 'fx:id'.
- Save the
.fxml
file.
Opening up the PersonOverviewController
to JavaFx
If you try and run the application now, you will encounter the following error:
javafx.fxml.LoadException: ...
...
Caused by: java.lang.IllegalAccessException: class javafx.fxml.FXMLLoader$ValueElement (in module javafx.fxml) cannot access class seedu.address.view.PersonOverviewController (in module AddressApp) because module AddressApp does not export seedu.address.view to module javafx.fxml
This is because JavaFx is unable to access our PersonOverviewController
class.
To fix this, add this line of code to src/module-info.java
:
module AddressApp {
...
opens seedu.address.view;
}
The file should now look something like this:
module-info.java
module AddressApp {
requires javafx.graphics;
requires javafx.fxml;
requires javafx.controls;
exports seedu.address;
opens seedu.address.view;
}
Start the Application
When you start your application now, you should see something like this:
Congratulations! The application now shows the list of Person
s in the view!
You may notice that selecting a person in the TableView
does nothing to the labels at the right side. That is because the user interaction portion has not been programmed yet, which we will cover in the next part of the tutorial.