从 TextField 更新 TreeView 项目

Question

这是我的一个非常简单的例子。（向下...）

它的作用： TreeView is populated with three Persons, when TreeItem is selected Textfield will be populated with name of the selected person.如果用户更改名称并从文本字段（或按 Enter）失去焦点，它将更改人员的名称和 "updates" TreeView 项目的显示文本。

我的问题是这一行：

selectedItem.valueProperty().set(new Person(selectedPerson.getName(), selectedPerson.getAge()));

多亏了那一行，我才能够刷新 TreeView。没有它，我只能在例如期间刷新 treeView。调整 window 的大小（或折叠和展开根项）。

我认为这个解决方案非常愚蠢，必须有更好的编码方式。我不能每次都创建一个新的 Person 实例，这对我来说是不可接受的。

我还尝试为 treeView 触发一个事件，但这种方法会混淆焦点，而且这也是一个愚蠢的解决方案。我还找到了这样的解决方案：

treeView.getRoot().getChildren().set(treeView.getSelectionModel().getSelectedIndex(), new TreeItem<MainAppTF.Person>(updatedPerson));

这也是一个糟糕的解决方案。

也许可以使用属性绑定找到解决方案，但绑定是一个 "realtime/instant" 变化，除非我使用 bind() unbind()，但也许 Binding 中有一些东西可以使用我还不熟。（我更喜欢听众）

我的主要目标是 "commit" 我对焦点更改或关键事件的更改，并在那一刻之后立即更新 TreeView。

PS: 如果能提供真实的例子，将不胜感激

public class MainAppTF extends Application {

    private TreeView<Person> treeView;
    private final TreeItem<Person> rootNode = new TreeItem<Person>(new Person("Root", 0));

    private TextField textField;

    @Override
    public void start(Stage stage) {
        VBox box = new VBox();
        Scene scene = new Scene(box, 400, 400);

        treeView = new TreeView<Person>(rootNode);
        treeView.setShowRoot(false);
        rootNode.setExpanded(true);

        List<TreeItem<Person>> list = new ArrayList<>();
        list.add(new TreeItem<Person>(new Person("Adam", 20)));
        list.add(new TreeItem<Person>(new Person("Eva", 19)));
        list.add(new TreeItem<Person>(new Person("Carl", 30)));
        rootNode.getChildren().setAll(list);

        textField = new TextField("");

        attachListeners();

        box.getChildren().add(treeView);
        box.getChildren().add(textField);
        VBox.setMargin(treeView, new Insets(10));
        VBox.setMargin(textField, new Insets(10));

        stage.setScene(scene);
        stage.show();
    }

    private void attachListeners() {
        treeView.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<TreeItem<Person>>() {
            @Override
            public void changed(ObservableValue<? extends TreeItem<Person>> observable, TreeItem<Person> oldValue, TreeItem<Person> newValue) {
                textField.setText(newValue.getValue().getName());
            }
        });

        textField.focusedProperty().addListener(new ChangeListener<Boolean>() {
            @Override
            public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
                if (!newValue) {
                    updateTreeViewItem();
                }
            }
        });

        textField.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                updateTreeViewItem();
            }
        });
    }

    private void updateTreeViewItem() {
        TreeItem<Person> selectedItem = treeView.getSelectionModel().getSelectedItem();
        Person selectedPerson = selectedItem.getValue();
        selectedPerson.nameProperty().set(textField.getText());

        // FIXME This is silly! There must be another way!
        selectedItem.valueProperty().set(new Person(selectedPerson.getName(), selectedPerson.getAge()));
    }

    public static void main(String[] args) {
        Application.launch(args);
    }

    private class Person {

        private StringProperty name;
        private int age;

        public Person() {
            this(null, 0);
        }

        public Person(String name, int age) {
            this.name = new SimpleStringProperty(name);
            this.age = age;
        }

        public StringProperty nameProperty() {
            return name;
        }

        public String getName() {
            return name.getValue();
        }

        public void setName(String name) {
            this.name.setValue(name);
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        @Override
        public String toString() {
            return getName() + " - " + getAge();
        }

    }

}

Answer 1

您希望 TreeItem 在 TreeItem 包装的 Person 的名称更改时接收 TreeModificationEvents。

您可以通过将侦听器附加到此人的 nameProperty()，然后触发适当的事件来执行此操作：

TreeItem<Person> treeItem = new TreeItem<>(person);
ChangeListener<String> nameListener = (obs, oldName, newName) -> {
    TreeModificationEvent<Person> event = new TreeModificationEvent<>(TreeItem.valueChangedEvent(), treeItem);
    Event.fireEvent(treeItem, event);
};
person.nameProperty().addListener(nameListener);

如果您有可能更改 TreeItem (treeItem.setValue(new Person(...))) 包装的值，那么您需要确保从 old person 中移除监听器并将其添加到新的一个。因此，谨慎的做法也可能是：

treeItem.valueProperty().addListener((obs, oldValue, newValue) -> {
    if (oldValue != null) {
        oldValue.nameProperty().removeListener(nameListener);
    }
    if (newValue != null) {
        newValue.nameProperty().addListener(nameListener);
    }
});

显然，您不想每次都重复这段代码，因此您可以创建一个实用方法：

private TreeItem<Person> createTreeItem(Person person) {
    TreeItem<Person> treeItem = new TreeItem<>(person);
    ChangeListener<String> nameListener = (obs, oldName, newName) -> {
        TreeModificationEvent<Person> event = new TreeModificationEvent<>(TreeItem.valueChangedEvent(), treeItem);
        Event.fireEvent(treeItem, event);
    };
    person.nameProperty().addListener(nameListener);
    treeItem.valueProperty().addListener((obs, oldValue, newValue) -> {
        if (oldValue != null) {
            oldValue.nameProperty().removeListener(nameListener);
        }
        if (newValue != null) {
            newValue.nameProperty().addListener(nameListener);
        }
    });
    return treeItem ;
}

然后

list.add(createTreeItem(new Person("Adam", 20)));
list.add(createTreeItem(new Person("Eva", 19)));
list.add(createTreeItem(new Person("Carl", 30)));

或者您可以创建 TreeItem<Person> 的子类：

private class PersonTreeItem extends TreeItem<Person> {

    private ChangeListener<String> nameListener = (obs, oldName, newName) -> {
        TreeModificationEvent<Person> event = new TreeModificationEvent<>(TreeItem.valueChangedEvent(), this);
        Event.fireEvent(this, event);
    };

    public PersonTreeItem(Person person) {
        super(person);
        person.nameProperty().addListener(nameListener);
        this.valueProperty().addListener((obs, oldValue, newValue) -> {
            if (oldValue != null) {
                oldValue.nameProperty().removeListener(nameListener);
            }
            if (newValue != null) {
                newValue.nameProperty().addListener(nameListener);
            }
        });
    }
}

并做

list.add(new PersonTreeItem(new Person("Adam", 20)));
list.add(new PersonTreeItem(new Person("Eva", 19)));
list.add(new PersonTreeItem(new Person("Carl", 30)));

（两者之间的选择本质上只是风格问题。）

SSCCE：

import java.util.ArrayList;
import java.util.List;

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeItem.TreeModificationEvent;
import javafx.scene.control.TreeView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class MainAppTF extends Application {

    private TreeView<Person> treeView;
    private final TreeItem<Person> rootNode = new TreeItem<Person>(new Person("Root", 0));

    private TextField textField;

    @Override
    public void start(Stage stage) {
        VBox box = new VBox();
        Scene scene = new Scene(box, 400, 400);

        treeView = new TreeView<Person>(rootNode);
        treeView.setShowRoot(false);
        rootNode.setExpanded(true);

        List<TreeItem<Person>> list = new ArrayList<>();
        list.add(createTreeItem(new Person("Adam", 20)));
        list.add(createTreeItem(new Person("Eva", 19)));
        list.add(createTreeItem(new Person("Carl", 30)));
        rootNode.getChildren().setAll(list);

        textField = new TextField("");

        attachListeners();

        box.getChildren().add(treeView);
        box.getChildren().add(textField);
        VBox.setMargin(treeView, new Insets(10));
        VBox.setMargin(textField, new Insets(10));

        stage.setScene(scene);
        stage.show();
    }

    private void attachListeners() {
        treeView.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<TreeItem<Person>>() {
            @Override
            public void changed(ObservableValue<? extends TreeItem<Person>> observable, TreeItem<Person> oldValue, TreeItem<Person> newValue) {
                textField.setText(newValue.getValue().getName());
            }
        });

        textField.focusedProperty().addListener(new ChangeListener<Boolean>() {
            @Override
            public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
                if (!newValue) {
                    updateTreeViewItem();
                }
            }
        });

        textField.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                updateTreeViewItem();
            }
        });
    }

    private void updateTreeViewItem() {
        TreeItem<Person> selectedItem = treeView.getSelectionModel().getSelectedItem();
        Person selectedPerson = selectedItem.getValue();
        selectedPerson.nameProperty().set(textField.getText());

        // FIXME This is silly! There must be another way!
//        selectedItem.valueProperty().set(new Person(selectedPerson.getName(), selectedPerson.getAge()));
    }

    public static void main(String[] args) {
        Application.launch(args);
    }


    private TreeItem<Person> createTreeItem(Person person) {
        TreeItem<Person> treeItem = new TreeItem<>(person);
        ChangeListener<String> nameListener = (obs, oldName, newName) -> {
            TreeModificationEvent<Person> event = new TreeModificationEvent<>(TreeItem.valueChangedEvent(), treeItem);
            Event.fireEvent(treeItem, event);
        };
        person.nameProperty().addListener(nameListener);
        treeItem.valueProperty().addListener((obs, oldValue, newValue) -> {
            if (oldValue != null) {
                oldValue.nameProperty().removeListener(nameListener);
            }
            if (newValue != null) {
                newValue.nameProperty().addListener(nameListener);
            }
        });
        return treeItem ;
    }

    private class Person {

        private StringProperty name;
        private int age;

        public Person() {
            this(null, 0);
        }

        public Person(String name, int age) {
            this.name = new SimpleStringProperty(name);
            this.age = age;
        }

        public StringProperty nameProperty() {
            return name;
        }

        public String getName() {
            return name.getValue();
        }

        public void setName(String name) {
            this.name.setValue(name);
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        @Override
        public String toString() {
            return getName() + " - " + getAge();
        }

    }

}

从 TextField 更新 TreeView 项目

Updating TreeView items from TextField

treeview

javafx

javafx-8