从 TextField 更新 TreeView 项目

Question

这是我非常简单的例子。（下...）

What it does: 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中失去焦点（或按 Enter），它将更改人员的名称并“更新”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()));

多亏了那条线，我才能刷新 TreeView。没有那个，我只能在例如调整窗口大小（或根项目的折叠和展开）期间刷新树视图。

我认为这个解决方案非常愚蠢，必须有一种方法可以更好地对其进行编码。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，而且它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));

这也是不好的解决方案。

也许可以使用属性绑定找到解决方案，但绑定是“实时/即时”更改，除非我使用 bind() unbind()，但也许 Binding 中有一些我还不熟悉的东西。（我更喜欢听众）

我的主要目标是“提交”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：我将非常感谢真实的例子。

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

您希望在更改包装的名称时TreeItem接收TreeModificationEvents。PersonTreeItem

您可以通过将侦听器附加到此nameProperty()人的 ，然后触发适当的事件来做到这一点：

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(...)))包裹的值，那么您需要确保从旧人中删除侦听器并将其添加到新人中。因此，也可以谨慎地执行以下操作：

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

显然，您不想每次都重复此代码，因此您可以创建一个实用程序方法：

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 ;
}

然后做

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

或者您可以创建一个子类TreeItem<Person>：

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();
        }

    }

}