向现有 TableView 添加复选框列

Question

我最近想向现有的

CheckBox

 添加一个 

TableView 列。为了单独研究这个问题，我从示例 13-6 创建表并向其中添加数据开始。我向

BooleanProperty

模型类添加了

Person

和访问器，并添加了一个新的

TableColumn

，其中

CheckBoxTableCell

作为单元工厂。如图所示，我在每一行上看到一个

CheckBox

。尽管所有值都是

true

，但没有一个被检查；复选框处于活动状态，但

setActive()

从未被调用。最近关于这个主题的问题表明我遗漏了一些东西；我欢迎任何见解。

import javafx.application.Application;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.SimpleBooleanProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.CheckBoxTableCell;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;

/**
 * Example 13-6 Creating a Table and Adding Data to It
 * https://docs.oracle.com/javase/8/javafx/user-interface-tutorial/table-view.htm#CJAGAAEE
 */
public class TableViewSample extends Application {

    private final TableView<Person> table = new TableView<>();
    private final ObservableList<Person> data
        = FXCollections.observableArrayList(
            new Person("Jacob", "Smith", "[email protected]"),
            new Person("Isabella", "Johnson", "[email protected]"),
            new Person("Ethan", "Williams", "[email protected]"),
            new Person("Emma", "Jones", "[email protected]"),
            new Person("Michael", "Brown", "[email protected]")
        );

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

    @Override
    public void start(Stage stage) {
        stage.setTitle("Table View Sample");
        stage.setWidth(600);
        stage.setHeight(400);

        final Label label = new Label("Address Book");
        label.setFont(new Font("Arial", 20));

        table.setEditable(true);

        TableColumn<Person, Boolean> active = new TableColumn<>("Active");
        active.setCellValueFactory(new PropertyValueFactory<>("active"));
        active.setCellFactory(CheckBoxTableCell.forTableColumn(active));

        TableColumn<Person, String> firstName = new TableColumn<>("First Name");
        firstName.setCellValueFactory(new PropertyValueFactory<>("firstName"));

        TableColumn<Person, String> lastName = new TableColumn<>("Last Name");
        lastName.setCellValueFactory(new PropertyValueFactory<>("lastName"));

        TableColumn<Person, String> email = new TableColumn<>("Email");
        email.setCellValueFactory(new PropertyValueFactory<>("email"));

        table.setItems(data);
        table.getColumns().addAll(active, firstName, lastName, email);

        final VBox vbox = new VBox();
        vbox.setSpacing(5);
        vbox.setPadding(new Insets(8));
        vbox.getChildren().addAll(label, table);

        stage.setScene(new Scene(vbox));
        stage.show();
    }

    public static class Person {

        private final BooleanProperty active;
        private final StringProperty firstName;
        private final StringProperty lastName;
        private final StringProperty email;

        private Person(String fName, String lName, String email) {
            this.active = new SimpleBooleanProperty(true);
            this.firstName = new SimpleStringProperty(fName);
            this.lastName = new SimpleStringProperty(lName);
            this.email = new SimpleStringProperty(email);
        }

        public boolean getActive() {
            return active.get();
        }

        public void setActive(boolean b) {
            active.set(b);
        }

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

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

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

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

        public String getEmail() {
            return email.get();
        }

        public void setEmail(String s) {
            email.set(s);
        }
    }
}

Answer 1

总结：如此处所述，这是一个未解决的问题；有关更多详细信息，请参阅 为什么我应该避免在 JavaFX 中使用

PropertyValueFactory

？；避免陷阱的步骤包括：

• 验证数据模型是否正确导出属性，如此处所示。
• 如

  here

  、

  here

  、here、here和here所述，严格检查用明确的PropertyValueFactory替换Callback的价值。

问题是

CheckBoxTableCell

无法根据提供的参数找到或绑定

ObservableProperty<Boolean>

：

active.setCellFactory(CheckBoxTableCell.forTableColumn(active));

CheckBoxTableCell

遵循表列来访问目标

Boolean

属性。要查看效果，请将

active

参数替换为

Callback

，它会显式返回行

ObservableValue<Boolean>

的

i

：

active.setCellFactory(CheckBoxTableCell.forTableColumn(
    (Integer i) -> data.get(i).active));

虽然这使复选框起作用，但根本问题是

Person

类需要

active

属性的访问器。 使用 JavaFX 属性和绑定 讨论属性方法命名约定，Ensemble8 Person

 的 

tablecellfactory 类说明了一个工作模型类，其中每个属性都有一个属性 getter，如下所示。

通过此更改

PropertyValueFactory

可以找到新添加的

BooleanProperty

，并且

forTableColumn()

的原始形式可以工作。请注意，

PropertyValueFactory

的便利也伴随着一些限制。特别是，工厂对先前缺失的属性访问器的失败支持没有被注意到。幸运的是，相同的访问器允许用简单的

Callback

替换每列的值工厂。如图这里，而不是

PropertyValueFactory

，

active.setCellValueFactory(new PropertyValueFactory<>("active"));

传递一个返回相应属性的lamda表达式：

active.setCellValueFactory(cd -> cd.getValue().activeProperty());

另请注意，

Person

现在可以是

private

。此外，使用显式类型参数可以在编译期间提供更强的类型检查。

import javafx.application.Application;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.SimpleBooleanProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.CheckBoxTableCell;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;

/**
 * https://stackoverflow.com/a/68969223/230513
 */
public class TableViewSample extends Application {

    private final TableView<Person> table = new TableView<>();
    private final ObservableList<Person> data
        = FXCollections.observableArrayList(
            new Person("Jacob", "Smith", "[email protected]"),
            new Person("Isabella", "Johnson", "[email protected]"),
            new Person("Ethan", "Williams", "[email protected]"),
            new Person("Emma", "Jones", "[email protected]"),
            new Person("Michael", "Brown", "[email protected]")
        );

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

    @Override
    public void start(Stage stage) {
        stage.setTitle("Table View Sample");
        stage.setWidth(600);
        stage.setHeight(400);

        final Label label = new Label("Address Book");
        label.setFont(new Font("Arial", 20));

        table.setEditable(true);

        TableColumn<Person, Boolean> active = new TableColumn<>("Active");
        active.setCellValueFactory(cd -> cd.getValue().activeProperty());
        active.setCellFactory(CheckBoxTableCell.forTableColumn(active));

        TableColumn<Person, String> firstName = new TableColumn<>("First Name");
        firstName.setCellValueFactory(cd -> cd.getValue().firstNameProperty());

        TableColumn<Person, String> lastName = new TableColumn<>("Last Name");
        lastName.setCellValueFactory(cd -> cd.getValue().lastNameProperty());

        TableColumn<Person, String> email = new TableColumn<>("Email");
        email.setCellValueFactory(cd -> cd.getValue().emailProperty());

        table.setItems(data);
        table.getColumns().addAll(active, firstName, lastName, email);

        final VBox vbox = new VBox();
        vbox.setSpacing(5);
        vbox.setPadding(new Insets(8));
        vbox.getChildren().addAll(label, table);

        stage.setScene(new Scene(vbox));
        stage.show();
    }

    private static class Person {

        private final BooleanProperty active;
        private final StringProperty firstName;
        private final StringProperty lastName;
        private final StringProperty email;

        private Person(String fName, String lName, String email) {
            this.active = new SimpleBooleanProperty(true);
            this.firstName = new SimpleStringProperty(fName);
            this.lastName = new SimpleStringProperty(lName);
            this.email = new SimpleStringProperty(email);
        }

        public BooleanProperty activeProperty() {
            return active;
        }

        public StringProperty firstNameProperty() {
            return firstName;
        }

        public StringProperty lastNameProperty() {
            return lastName;
        }

        public StringProperty emailProperty() {
            return email;
        }
    }
}