Question

我是JavaFX的新手，我不知道如何解决这个问题。所以，我在TableView中有一个复选框列。例如，我选择3个第一个框并向下滚动表格。但是当我转到表格顶部时，未选中复选框。这是一些代码：

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;
import javafx.util.Callback;
import java.util.LinkedList;
import java.util.List;

public class App extends Application
{
List<User> list = new LinkedList<>();
TableColumn<User, Integer> id;
TableColumn<User, String> firstName;
TableColumn<User, Boolean> selected;
TableView<User> tableView;

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

@Override
public void start(Stage stage) throws Exception
{
    stage.setHeight(500);
    stage.setWidth(500);
    stage.setMinHeight(200);
    stage.setMinHeight(100);
    stage.setTitle("Table view");

    tableView = new TableView<>();

    ObservableList<User> list = FXCollections.observableArrayList();
    for(int i = 0; i < 40; i++)
    {
        list.add(new User(i, "first name", "last name"));
    }

    id = new TableColumn("ID");
    id.setCellValueFactory(new PropertyValueFactory<User, Integer>("id"));

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

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

    selected = new TableColumn("Select");

    Callback<TableColumn<User, Boolean>, TableCell<User, Boolean>> booleanCellFactory =     new Callback<TableColumn<User, Boolean>, TableCell<User, Boolean>>()
    {
        @Override
        public TableCell<User, Boolean> call(TableColumn<User, Boolean> p)
        {
            return new CheckBoxCell();
        }
    };
    selected.setCellValueFactory(new PropertyValueFactory<User, Boolean>("active"));
    selected.setCellFactory(booleanCellFactory);

    tableView.getColumns().addAll(id, firstName, lastName, selected);
    tableView.setItems(list);

    BorderPane pane = new BorderPane();
    pane.setCenter(tableView);

    Scene scene = new Scene(pane);
    stage.setScene(scene);
    stage.show();
}

class CheckBoxCell extends TableCell<User, Boolean>
{
    private CheckBox checkbox;

    @Override
    protected void updateItem(Boolean item, boolean empty)
    {
        super.updateItem(item, empty);
        checkbox = new CheckBox();
        checkbox.setAlignment(Pos.CENTER);
        setAlignment(Pos.CENTER);
        setGraphic(checkbox);
        checkbox.setOnAction(new EventHandler<ActionEvent>()
        {
            @Override
            public void handle(ActionEvent actionEvent)
            {

                if(!checkbox.isSelected())
                {
                    list.remove(tableView.getItems().get(getTableRow().getIndex()));
                } else
                {
                    list.add(tableView.getItems().get(getTableRow().getIndex()));
                }
                System.out.println(list);
            }
        });
    }
}
}

数据类“User”：

public class User
{
private int id;
private String firstName;
private String lastName;

User(int id, String firstName, String lastName)
{
    this.id = id;
    this.firstName = firstName;
    this.lastName = lastName;
}

public int getId()
{
    return id;
}

public void setId(int id)
{
    this.id = id;
}

public String getFirstName()
{
    return firstName;
}

public void setFirstName(String firstName)
{
    this.firstName = firstName;
}

public String getLastName()
{
    return lastName;
}

public void setLastName(String lastName)
{
    this.lastName = lastName;
}

}

Answer 1

在Table Column“slected”

的代码中

selected.setCellValueFactory(new PropertyValueFactory<User, Boolean>("active"));

您将属性值工厂设置为“活动”但您的用户类中没有“活动”属性。当您移动滚动条tableview触发器updateItem方法时，因为您没有活动属性（即使您有属性默认值） value为false）checkbox.setSelected（item）; line将取消选中复选框，因为项值始终为false。

要解决此问题，请在用户选择/取消选中复选框时定义在用户类中激活的BooleanProperty和更新属性值。

以下是正在运行的整个代码

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.stage.Stage;
import javafx.util.Callback;
import javafx.scene.layout.BorderPane;
import java.util.LinkedList;
import java.util.List;

public class TestApp extends Application {

        List<User> list = new LinkedList<>();
        TableColumn<User, Integer> id;
        TableColumn<User, String> firstName;
        TableColumn<User, Boolean> selected;
        TableView<User> tableView;

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

@Override
public void start(Stage stage) throws Exception
        {
        stage.setHeight(500);
        stage.setWidth(500);
        stage.setMinHeight(200);
        stage.setMinHeight(100);
        stage.setTitle("Table view");

        tableView = new TableView<>();

        ObservableList<User> list = FXCollections.observableArrayList();
        for(int i = 0; i < 40; i++)
        {
        list.add(new User(i, "first name", "last name"));
        }

        id = new TableColumn("ID");
        id.setCellValueFactory(new PropertyValueFactory<User, Integer>("id"));

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

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

        selected = new TableColumn("Select");

        Callback<TableColumn<User, Boolean>, TableCell<User, Boolean>> booleanCellFactory =     new Callback<TableColumn<User, Boolean>, TableCell<User, Boolean>>()
        {
@Override
public TableCell<User, Boolean> call(TableColumn<User, Boolean> p)
        {
        return new CheckBoxCell();
        }
        };
        selected.setCellValueFactory(new PropertyValueFactory<User, Boolean>("active"));
        selected.setCellFactory(booleanCellFactory);

        tableView.getColumns().addAll(id, firstName, lastName, selected);
        tableView.setItems(list);

        BorderPane pane = new BorderPane();
        pane.setCenter(tableView);

        Scene scene = new Scene(pane);
        stage.setScene(scene);
        stage.show();
       }

class CheckBoxCell extends TableCell<User, Boolean>
{
    private CheckBox checkbox = new CheckBox();
    public CheckBoxCell(){
        checkbox.setOnAction(new EventHandler<ActionEvent>()
        {
            @Override
            public void handle(ActionEvent actionEvent)
            {

                if(!checkbox.isSelected())
                {
                    list.remove(tableView.getItems().get(getTableRow().getIndex()));
                    User user = getTableView().getItems().get(getTableRow().getIndex());
                    user.setActive(false);
                } else
                {
                    list.add(tableView.getItems().get(getTableRow().getIndex()));
                    User user = getTableView().getItems().get(getTableRow().getIndex());
                    user.setActive(true);
                }
                System.out.println(list);
            }
        });
    }

    @Override
    protected void updateItem(Boolean item, boolean empty)
    {
        super.updateItem(item, empty);
       if(!empty && item != null) {
           checkbox.setAlignment(Pos.CENTER);
           checkbox.setSelected(item);
           setAlignment(Pos.CENTER);
           setGraphic(checkbox);
       }
    }
}

用户类：

public class User
{
    private IntegerProperty id;
    private StringProperty firstName;
    private StringProperty lastName;
    private BooleanProperty active;

    User(int id, String firstName, String lastName)
    {
        this.id = new SimpleIntegerProperty(id);
        this.firstName = new SimpleStringProperty(firstName);
        this.lastName = new SimpleStringProperty(lastName);
        this.active = new SimpleBooleanProperty(false);
    }

    public int getId() {
        return id.get();
    }

    public IntegerProperty idProperty() {
        return id;
    }

    public void setId(int id) {
        this.id.set(id);
    }

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

    public StringProperty firstNameProperty() {
        return firstName;
    }

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

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

    public StringProperty lastNameProperty() {
        return lastName;
    }

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

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

    public BooleanProperty activeProperty() {
        return active;
    }

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

Answer 2

有很多问题。

首先，TableCell个实例将被重用。您需要将CheckBox的值设置为item的值。

@Override
protected void updateItem(Boolean item, boolean empty)
{
    super.updateItem(item, empty);
    checkbox = new CheckBox();

    if(!empty && item != null)
        checkbox.setSelected(item);

    ....

  }

其次，您有两个名为list的变量。 TableView未绑定到顶部声明的List<User>，这可能就是您的行不会自行删除的原因。

你应该替换这一行：

List<User> list = new LinkedList<>();

有了这个：

ObservableList<User> list = FXCollections.observableArrayList();

最后，您应该为数据对象使用JavaFX属性，它们将使用TableView执行得更快（无需使用反射来访问值），并且可以使用JavaFX控件提供更好的处理。

You can learn about the properties on the Oracle website.

如何在滚动时修复TableView

2 个答案: