JavaFX Binding to Custom Object

Question

I'm learning the binding concept in Java FX. I have a Person class which has firstName and lastName which are of type SimpleStringProperty. In my FXML, I have two text fields, and a label. When the user enters the First Name and last Name, I need to display that in the Label as Full Name.

I'm getting NullPointerException when trying person.get().firstNameProperty(). How do I implement this sample requirement?

 public class CustomControl extends Pane{

        @FXML
        private TextField firstNameTextField, lastNameTextField;

        @FXML
        private Label fullNameLabel;

        private ObjectProperty<Person> person = new SimpleObjectProperty<Person>( this, "person" );

        public CustomControl(){

            try{
                FXMLLoader loader = new FXMLLoader( this.getClass().getResource( "EnterDetails.fxml" ) );
                loader.setController( this );
                loader.load();

                registerListeners();
            }
            catch( IOException e ){
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        /**
         */
        private void registerListeners(){

            firstNameTextField.textProperty().bind( person.get().firstNameProperty() );
            lastNameTextField.textProperty().bind( person.get().lastNameProperty() );

            fullNameLabel.textProperty().bind( Bindings.concat( person.get().firstNameProperty() ).concat( person.get().lastNameProperty() ) );
        }

        public ObjectProperty<Person> personProperty(){
            return person;
        }

        public Person getPerson(){
            return personProperty().get();
        }

        public void setPerson( Person person ){
            personProperty().set( person );
        }
    }

Below is the Person class

public class Person{
    private SimpleStringProperty firstName=new SimpleStringProperty();
    private SimpleStringProperty lastName=new SimpleStringProperty();

    public String getFirstName(){
        return firstNameProperty().get();
    }

    public void setFirstName( String firstName ){
        firstNameProperty().set( firstName );
    }

    public SimpleStringProperty firstNameProperty(){
        return firstName;
    }

    public String getLastName(){
        return lastNameProperty().get();
    }

    public void setLastName( String lastName ){
        lastNameProperty().set( lastName );
    }

    public SimpleStringProperty lastNameProperty(){
        return lastName;
    }
}

This is the FXML page

<GridPane xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8">
   <rowConstraints>
      <RowConstraints minHeight="10.0" prefHeight="30.0" />
      <RowConstraints minHeight="10.0" prefHeight="30.0" />
      <RowConstraints minHeight="10.0" prefHeight="30.0" />
   </rowConstraints>
   <columnConstraints>
      <ColumnConstraints minWidth="10.0" prefWidth="100.0" />
      <ColumnConstraints minWidth="10.0" prefWidth="100.0" />
   </columnConstraints>
   <children>
      <Label text="FirstName" />
      <Label text="Last Name" GridPane.rowIndex="1" />
      <TextField fx:id="firstNameTextField" GridPane.columnIndex="1" />
      <TextField fx:id="lastNameTextField" GridPane.columnIndex="1" GridPane.rowIndex="1" />
      <Label fx:id="fullNameLabel" GridPane.rowIndex="2" />
   </children>
</GridPane>

eckig eckig · Accepted Answer · 2015-01-13T05:43:20

In your code you never called public void setPerson( Person person ){ so the ObjectProperty person holds the value null and person.get() returns null.

JavaFX Binding to Custom Object

1 Answers