How to bind multiple properties to one observable in JavaFX [closed] - javafx

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Update 3: solution
I finally got it: just save a reference of MyRoot in a property:
MainApp
package my.group.javafxtestbinding;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
public class MainApp extends Application {
private MyRoot root;
#Override
public void start(Stage primaryStage) {
root = new MyRoot();
HBox parent = root.myRoot;
Scene scene = new Scene(parent, 600, 400);
primaryStage.setScene(scene);
primaryStage.show();
Button gcButton = new Button("Collect Garbage");
gcButton.setOnMousePressed(event -> System.gc());
parent.getChildren().add(gcButton);
}
public static void main(String[] args) {
launch(args);
}
}
Update 3 solution end
Update 2:
So, I'm still having problems with losing my bindings and it's due to garbage collection; that I can reproduce. See the follwing Minimal Working Example.
The structure of the example is somewhat special, that is because I use the MVP framework from Adam Bien: afterburner.fx. And I wanted to simulate the same structure in my example.
I read a lot (i.e. here, here) and understand the basic problem but still can't really grasp it.
I'm somewhat new to JavaFX, hope somebody can give me a hint.
Reproduce:
When you click on an item in the table, the content of the label changes due to the binding between the selected model in the table (Select) and the label (Show). MyRoot manages both.
When you click on the button garbage collection is executed and the binding is gone.
MainApp
package my.group.javafxtestbinding;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
public class MainApp extends Application {
#Override
public void start(Stage primaryStage) {
MyRoot root = new MyRoot();
HBox parent = root.myRoot;
Scene scene = new Scene(parent, 600, 400);
primaryStage.setScene(scene);
primaryStage.show();
Button gcButton = new Button("Collect Garbage");
gcButton.setOnMousePressed(event -> System.gc());
parent.getChildren().add(gcButton);
}
public static void main(String[] args) {
launch(args);
}
}
MyRoot
package my.group.javafxtestbinding;
import javafx.scene.layout.HBox;
public class MyRoot {
public HBox myRoot;
private final Select select;
private final Show show;
public MyRoot() {
select = new Select();
show = new Show();
myRoot = new HBox();
myRoot.getChildren().addAll(select.myTable, show.myLabel);
show.selectedModelProperty().bind(select.selectedModelProperty());
}
}
Select
package my.group.javafxtestbinding;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
public class Select {
private ObjectProperty<MyModel> selectedModel;
public TableView<MyModel> myTable;
private final TableColumn<MyModel, String> myColumn;
public Select() {
this.selectedModel = new SimpleObjectProperty<>();
myTable = new TableView();
myColumn = new TableColumn("Name");
myTable.getColumns().add(myColumn);
myTable.setItems(getList());
myColumn.setCellValueFactory(cellData -> cellData.getValue().getNameProperty());
ChangeListener<MyModel> changeListener = new ChangeListener<MyModel>() {
#Override
public void changed(ObservableValue<? extends MyModel> observable, MyModel oldValue, MyModel newValue) {
selectedModel.set(newValue);
}
};
myTable.getSelectionModel().selectedItemProperty().addListener(changeListener);
}
public ObjectProperty<MyModel> selectedModelProperty() {
return selectedModel;
}
private ObservableList<MyModel> getList() {
MyModel model1 = new MyModel("Joe");
MyModel model2 = new MyModel("Jim");
MyModel model3 = new MyModel("Jack");
ObservableList<MyModel> list = FXCollections.observableArrayList(model1, model2, model3);
return list;
}
}
Show
package my.group.javafxtestbinding;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.control.Label;
public class Show {
private ObjectProperty<MyModel> selectedModel;
public Label myLabel;
public Show() {
this.selectedModel = new SimpleObjectProperty<>();
myLabel = new Label("Init");
ChangeListener listener = new ChangeListener<MyModel>() {
#Override
public void changed(ObservableValue<? extends MyModel> observable, MyModel oldValue, MyModel newValue) {
if (newValue != null) {
myLabel.setText(newValue.getName());
}
}
};
this.selectedModel.addListener(listener);
}
public ObjectProperty<MyModel> selectedModelProperty() {
return selectedModel;
}
}
MyModel
package my.group.javafxtestbinding;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
public class MyModel {
private final StringProperty name;
public MyModel(String name) {
this.name = new SimpleStringProperty(name);
}
public String getName() {
return name.get();
}
public void setName(String name) {
this.name.set(name);
}
public StringProperty getNameProperty() {
return name;
}
}
Update 2 end
Update 1:
Ok, thank you for your comments.
I thought I was doing it wrong. But if you say that this is the correct way then the problem must be somewhere else. I will post it when I find the problem...
Update 1 end
Original Post:
I have problems binding many properties to one observable.
Let's say I have three (or more) properties ObjectProperty<Foo> firstProp in FirstObject, ObjectProperty<Foo> secondProp in SecondObject and ObjectProperty<Foo> thirdProp in ThirdObject.
How can I bind second and third property to the first which is the observable.
So when firstProp changes the ChangeListeners attached to secondProp and thirdProp will be fired.
What I tried:
SecondObject.secondProperty().bind(FirstObject.firstProperty());
ThirdObject.thirdProperty().bind(FirstObject.firstProperty());
The result is that it sometimes works and sometimes not. If I add more bindings in the same way they do not work at all.
Is this not working because of this:
Note that JavaFX has all the bind calls implemented through weak listeners. This means the bound property can be garbage collected and stopped from being updated.
Javadoc bind()
I find a lot of answers to how to bind many observables to one property, but not the other way.
Can somebody point me in the right direction?