Dynamic JavaFX Bindings - javafx-2

Question

My application has to deal with dynamic bindings.
I have a list of Java Bean objects that has a lot of attributes that must be editted.
There are multiple types of objects with different attributes.
I create a TreeView to list the objects.
Each time I select one object in the TreeView, I update a second container in the screen where I create dynamically the Labels and TextFields that are bound to the current object's properties.
I use JavaBeanStringProperty, JavaBeanIntegerProperty, and other objects of this family to create a property to interact with the Java Bean. That works perfectly.
I link each of those JavaBeanProperty objects to their corresponding TextField's TextAttribute so I can update the Bean when the UI is changed and vice-versa.
The problem is: Everytime I select a new Java Bean in the TreeView, all the objects previously created dynamically seem to be still alive. It will work for the first time I select the Bean and edit that, but for the second time further, it won't work.
I tried creating a list of created bindings so I can unbind them when selecting a new Bean, however it is not possible, since StringProperties and IntegerProperties do not share a common interface so I can unbind them.
Does anyone have an idea on how to deal with that?
Example:
Beans and their properties:
Bean1: name (String), amount (integer)
Bean2: name (String), type (String)
Bean3: name (String), address (string)
If I select the Bean1, I clear the container, and add those new objects to that:
A TextField to represent the name, a JavaBeanStringProperty to interface with the Bean, and bind it bidirectinally with the text field's TextProperty.
A TextField to represent the amount, a JavaBeanIntegerProperty to interface with the Bean, and bind it bidirectionally with the text field's TextProperty using a NumberConverter.
When I select the Bean2, I clear the container, and add those new objects to that:
A TextField to represent the name, a JavaBeanStringProperty to interface with the Bean, and bind it bidirectinally with the text field's TextProperty.
A TextField to represent the type, a JavaBeanStringProperty to interface with the Bean, and bind it bidirectionally with the text field's TextProperty.
When I select the Bean3, I clear the container, and add those new objects to that:
A TextField to represent the name, a JavaBeanStringProperty to interface with the Bean, and bind it bidirectinally with the text field's TextProperty.
A TextField to represent the address, a JavaBeanStringProperty to interface with the Bean, and bind it bidirectionally with the text field's TextProperty.
Here is a complete code example:
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.lang.ref.WeakReference;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.adapter.JavaBeanIntegerProperty;
import javafx.beans.property.adapter.JavaBeanIntegerPropertyBuilder;
import javafx.beans.property.adapter.JavaBeanStringProperty;
import javafx.beans.property.adapter.JavaBeanStringPropertyBuilder;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.SelectionMode;
import javafx.scene.control.TextField;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.converter.NumberStringConverter;
public class Main extends Application {
//=============================================================================================
public abstract class Bean {
public abstract void createUI(Pane container);
}
//=============================================================================================
public class Bean1 extends Bean {
private String name;
private int amount;
private PropertyChangeSupport pcs = new PropertyChangeSupport(this);
public Bean1(String name, int amount) {
this.name = name;
this.amount = amount;
}
public String toString() { return name; }
public void addPropertyChangeListener(PropertyChangeListener listener) {
pcs.addPropertyChangeListener(listener);
System.out.println("Bean 1 PCS has " + pcs.getPropertyChangeListeners().length + " listeners. 1 was possuibly added.");
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
pcs.removePropertyChangeListener(listener);
System.out.println("Bean 1 PCS has " + pcs.getPropertyChangeListeners().length + " listeners. 1 was possuibly removed.");
}
public String getName() { return name; }
public void setName(String name) {
String last = this.name;
this.name = name;
pcs.firePropertyChange("name", last, this.name);
System.out.println("Bean 1: name changed: " + last + " -> " + this.name);
}
public int getAmount() { return amount; }
public void setAmount(int amount) {
int last = this.amount;
this.amount = amount;
pcs.firePropertyChange("amount", last, this.amount);
System.out.println("Bean 1: amount changed: " + last + " -> " + this.amount);
}
public void createUI(Pane container) {
HBox nameContainer = new HBox();
Label nameLabel = new Label("name: ");
nameLabel.setPrefWidth(80);
TextField nameValue = new TextField();
nameValue.setPrefWidth(140);
try {
JavaBeanStringProperty wrapper = new JavaBeanStringPropertyBuilder().bean(this).name("name").build();
nameValue.textProperty().bindBidirectional(wrapper);
} catch (NoSuchMethodException e) {
e.printStackTrace();
System.out.println("Exception binding Bean 1 name property.");
}
nameContainer.getChildren().addAll(nameLabel, nameValue);
HBox amountContainer = new HBox();
Label amountLabel = new Label("amount: ");
amountLabel.setPrefWidth(80);
TextField amountValue = new TextField();
amountValue.setPrefWidth(140);
try {
JavaBeanIntegerProperty wrapper = new JavaBeanIntegerPropertyBuilder().bean(this).name("amount").build();
Bindings.bindBidirectional(amountValue.textProperty(), wrapper, new NumberStringConverter());
} catch (NoSuchMethodException e) {
e.printStackTrace();
System.out.println("Exception binding Bean 1 amount property.");
}
amountContainer.getChildren().addAll(amountLabel, amountValue);
container.getChildren().clear();
container.getChildren().addAll(nameContainer, amountContainer);
}
}
//=============================================================================================
public class Bean2 extends Bean {
private String name;
private String type;
private PropertyChangeSupport pcs = new PropertyChangeSupport(this);
public Bean2(String name, String type) {
this.name = name;
this.type = type;
}
public String toString() { return name; }
public void addPropertyChangeListener(PropertyChangeListener listener) {
pcs.addPropertyChangeListener(listener);
System.out.println("Bean 2 PCS has " + pcs.getPropertyChangeListeners().length + " listeners. 1 was possuibly added.");
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
pcs.removePropertyChangeListener(listener);
System.out.println("Bean 2 PCS has " + pcs.getPropertyChangeListeners().length + " listeners. 1 was possuibly removed.");
}
public String getName() { return name; }
public void setName(String name) {
String last = this.name;
this.name = name;
pcs.firePropertyChange("name", last, this.name);
System.out.println("Bean 2: name changed: " + last + " -> " + this.name);
}
public String getType() { return type; }
public void setType(String type) {
String last = this.type;
this.type = type;
pcs.firePropertyChange("type", last, this.type);
System.out.println("Bean 2: type changed: " + last + " -> " + this.type);
}
public void createUI(Pane container) {
HBox nameContainer = new HBox();
Label nameLabel = new Label("name: ");
nameLabel.setPrefWidth(80);
TextField nameValue = new TextField();
nameValue.setPrefWidth(140);
try {
JavaBeanStringProperty wrapper = new JavaBeanStringPropertyBuilder().bean(this).name("name").build();
nameValue.textProperty().bindBidirectional(wrapper);
} catch (NoSuchMethodException e) {
e.printStackTrace();
System.out.println("Exception binding Bean 2 name property.");
}
nameContainer.getChildren().addAll(nameLabel, nameValue);
HBox typeContainer = new HBox();
Label typeLabel = new Label("type: ");
typeLabel.setPrefWidth(80);
TextField typeValue = new TextField();
typeValue.setPrefWidth(140);
try {
JavaBeanStringProperty wrapper = new JavaBeanStringPropertyBuilder().bean(this).name("type").build();
typeValue.textProperty().bindBidirectional(wrapper);
} catch (NoSuchMethodException e) {
e.printStackTrace();
System.out.println("Exception binding Bean 2 type property.");
}
typeContainer.getChildren().addAll(typeLabel, typeValue);
container.getChildren().clear();
container.getChildren().addAll(nameContainer, typeContainer);
}
}
//=============================================================================================
public class Bean3 extends Bean {
private String name;
private String address;
private PropertyChangeSupport pcs = new PropertyChangeSupport(this);
public Bean3(String name, String address) {
this.name = name;
this.address = address;
}
public String toString() { return name; }
public void addPropertyChangeListener(PropertyChangeListener listener) {
pcs.addPropertyChangeListener(listener);
System.out.println("Bean 3 PCS has " + pcs.getPropertyChangeListeners().length + " listeners. 1 was possuibly added.");
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
pcs.removePropertyChangeListener(listener);
System.out.println("Bean 3 PCS has " + pcs.getPropertyChangeListeners().length + " listeners. 1 was possuibly removed.");
}
public String getName() { return name; }
public void setName(String name) {
String last = this.name;
this.name = name;
pcs.firePropertyChange("name", last, this.name);
System.out.println("Bean 3: name changed: " + last + " -> " + this.name);
}
public String getAddress() { return address; }
public void setAddress(String address) {
String last = this.address;
this.address = address;
pcs.firePropertyChange("type", last, this.address);
System.out.println("Bean 3: address changed: " + last + " -> " + this.address);
}
public void createUI(Pane container) {
HBox nameContainer = new HBox();
Label nameLabel = new Label("name: ");
nameLabel.setPrefWidth(80);
TextField nameValue = new TextField();
nameValue.setPrefWidth(140);
try {
JavaBeanStringProperty wrapper = new JavaBeanStringPropertyBuilder().bean(this).name("name").build();
nameValue.textProperty().bindBidirectional(wrapper);
} catch (NoSuchMethodException e) {
e.printStackTrace();
System.out.println("Exception binding Bean 3 name property.");
}
nameContainer.getChildren().addAll(nameLabel, nameValue);
HBox addressContainer = new HBox();
Label addressLabel = new Label("type: ");
addressLabel.setPrefWidth(80);
TextField addressValue = new TextField();
addressValue.setPrefWidth(140);
try {
JavaBeanStringProperty wrapper = new JavaBeanStringPropertyBuilder().bean(this).name("address").build();
addressValue.textProperty().bindBidirectional(wrapper);
} catch (NoSuchMethodException e) {
e.printStackTrace();
System.out.println("Exception binding Bean 3 address property.");
}
addressContainer.getChildren().addAll(addressLabel, addressValue);
container.getChildren().clear();
container.getChildren().addAll(nameContainer, addressContainer);
}
}
//=============================================================================================
private class TreeItemRefresher implements PropertyChangeListener {
private String property;
private WeakReference<TreeItem<Bean>> treeItem;
TreeItemRefresher(String property, TreeItem<Bean> treeItem) {
this.property = property;
this.treeItem = new WeakReference<>(treeItem);
}
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (property.equals(evt.getPropertyName())) {
// Workaround to repaint the tree item when its value object changes.
TreeItem<Bean> item = treeItem.get();
if (item != null) {
item.setExpanded(false);
item.setExpanded(true);
}
}
}
}
//=============================================================================================
private TreeView<Bean> treeView = new TreeView<>();
private VBox container = new VBox();
//=============================================================================================
#SuppressWarnings("unchecked")
#Override
public void start(Stage primaryStage) {
primaryStage.setTitle("Dynamic Bindings tests.");
HBox mainContainer = new HBox();
container.setPadding(new Insets(10));
// Creating beans.
Bean1 bean1 = new Bean1("Bean 1", 10);
Bean2 bean2 = new Bean2("Bean 2", "Type O");
Bean3 bean3 = new Bean3("Bean 3", "10, Central Park Av.");
// Creating TreeView
treeView.getSelectionModel().setSelectionMode(SelectionMode.SINGLE);
treeView.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<TreeItem<Bean>>() {
#Override
public void changed(ObservableValue<? extends TreeItem<Bean>> arg0, TreeItem<Bean> oldValue, TreeItem<Bean> newValue) {
Bean newItem = newValue.getValue();
newItem.createUI(container);
}
});
TreeItem<Bean> bean1item = new TreeItem<Bean>(bean1);
bean1.addPropertyChangeListener(new TreeItemRefresher("name", bean1item));
TreeItem<Bean> bean2item = new TreeItem<Bean>(bean2);
bean2.addPropertyChangeListener(new TreeItemRefresher("name", bean2item));
TreeItem<Bean> bean3item = new TreeItem<Bean>(bean3);
bean3.addPropertyChangeListener(new TreeItemRefresher("name", bean3item));
bean1item.setExpanded(true);
treeView.setRoot(bean1item);
bean1item.getChildren().addAll(bean2item, bean3item);
mainContainer.getChildren().addAll(treeView, container);
Scene scene = new Scene(mainContainer, 500, 300, Color.WHITE);
primaryStage.setScene(scene);
primaryStage.show();
}
//=============================================================================================
public Main() {
}
//=============================================================================================
public static void main(String[] args) {
launch(Main.class, args);
}
}
Notice sometimes changes to a field is not handled perfectly.
Notice also the number of PropertyChangeListeners are always increasing as you change the selected Bean. I know why that happens, but I really don't know how to deal with that.
Is there a better way to do it?
Notice I can't change the Bean objects. They are not under my control.
Thanks very much.

Answer 1

Did you try using JFXtras BeanPathAdaptor? It is a wonderful library for dynamic bindings based on POJOS.
You just have to use
beanPathAdaptor.setBean(myNewBean);
When you want to change your bean!
Here is a link:
http://ugate.wordpress.com/2012/07/30/javafx-programmatic-pojo-expression-bindings-part-iii/
EDIT
The other way I see is to define 3 custom components in JavaFX, one for each type. In them you define the complete binding to your bean with the view binded to your bean and add an input method such as "setBean1(Bean1 bean)"
Then, on selection you instanciate this component, show it and set its content with "setBean1(...)". You can do the same with the other types. Of course all of the bindings are static now, but the creation and use of components are dynamics, it is component-oriented and is high-coupled (view-model).
To optimize it, you can keep all the already created components in memory and use them again after to prevent from paying the instanciation of the view again, best way should be setting them to visible==false when you don't use them, you could even make an eager instanciation of all possible cases of components at initialization if you prefer.