java - 尝试提交 TableCell 时调用 cancelEdit()

Question

我正在尝试提交一个 TableCell，但正在调用 cancelEdit()。只有当我通过调用 tableView.edit() 使 cell 进入编辑状态时才会发生这种情况。

我通过以下方式调用 editCommit():

private void handleKeyPressed(KeyEvent e) {
    if (e.getCode() == KeyCode.ENTER) {
        commitEdit(textField.getText());
    }
}

为什么在按下回车键时调用 cancelEdit()？手动单击添加的空白行并尝试通过按 enter 键提交单元格可以正常工作。

import java.util.function.Function;
import javafx.application.Application;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.scene.control.TableView;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TextField;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.beans.property.SimpleStringProperty;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) {
        BorderPane root = new BorderPane();
        primaryStage.setScene(new Scene(root, 400, 400));
        primaryStage.show();
        root.setCenter(new TableExample());
    }

    public class TableExample extends VBox {
        public TableExample() {
            TableView<Building> tableView = new TableView<>();
            tableView.setEditable(true);

            //adds a new blank row to table;
            Button add = new Button("add");
            add.setOnAction(e -> {
                Building newBuilding = new Building();
                tableView.getItems().add(0, newBuilding);
                tableView.edit(0, tableView.getColumns().get(0));

                //I tried focusing and selecting the row
                //but does not help.
                tableView.getFocusModel().focus(0);
                tableView.getSelectionModel().select(0);

            });

            getChildren().addAll(add, tableView);

            Building building = new Building();
            building.setName("Building 100");

            Function<Building, StringProperty> property = Building::nameProperty;

            TableColumn<Building, String> column = new TableColumn<>("name");
            column.setEditable(true);
            column.setCellValueFactory(cellData -> property.apply(cellData.getValue()));
            column.setCellFactory(p -> new EditingStringCell<>());

            tableView.getColumns().add(column);
            tableView.setItems(FXCollections.observableArrayList(building));
        }
    }

    public class EditingStringCell<S, T> extends TableCell<Building, String> {
        private TextField textField;

        public EditingStringCell() {
            setEditable(true);
        }

        @Override
        protected void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            setText(empty ? null : item);
        }

        @Override
        public void startEdit() {
            System.out.println("start edit");
            super.startEdit();
            buildControl(getItem());
            setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
        }

        private void buildControl(String item) {
            System.out.println("item: " + item);
            textField = new TextField();        
            textField.addEventHandler(KeyEvent.KEY_RELEASED, 
            this::handleKeyPressed);
            textField.setText(item == null ? "" : (item));
            setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
            setGraphic(textField);
        }

        //whenever pressing enter on a new "blank" row
        //cancelEdit() gets called. But if you try again 
        //it works.
        private void handleKeyPressed(KeyEvent e) {
            if (e.getCode() == KeyCode.ENTER) {
                commitEdit(textField.getText());
            }
        }

        @Override
        public void cancelEdit() {
            System.out.println("cancel edit");
            super.cancelEdit();
            setContentDisplay(ContentDisplay.TEXT_ONLY);
        }

        @Override
        public void commitEdit(String newValue) {
            System.out.println("commited: " + newValue);
            super.commitEdit(newValue);
            setContentDisplay(ContentDisplay.TEXT_ONLY);
        }
    }

    public class Building {
        private final StringProperty name = new SimpleStringProperty();
        public StringProperty nameProperty() {
            return name;
        }
        public String getName() {
            return name.get();
        }
        public void setName(String name) {
            this.name.set(name);
        }
    }
    public static void main(String[] args) {launch(args);}
}

Answer 1

基本上，当涉及到 terminating an on-going edit 时，TableView(和其他虚拟化控件)表现得非常糟糕: 大多数情况下，当可用性需要提交时，它会取消编辑。

在您的示例中，有两个不同的(众所周知的)原因

1. 修改项目列表时，在内部深处取消了一个编辑，这里添加了一个项目
2. 当检测到表的编辑位置发生变化时，编辑 tableCell 本身会取消编辑

为了看看，我在你的代码中添加了一些打印:

演示问题 1:

• 编辑第一项
• 点击添加按钮
• 预期:已编辑的项目已保存，新项目开始编辑
• 实际:编辑项未保存，新项开始编辑

打印输出:

start edit 0 on id: 2
before adding: TablePosition [ row: 0, column: ... ]
cancel edit 0 on id: 2
start edit 0 on id: 2
start edit 0 on id: 14   // <- some slightly weird cell re-use
cancel edit 12 on id: 2  // <- triggers a cancel on the old, functional interference unknown 

演示问题 2:

• 添加一个项目并编辑任何
• 点击编辑开始编辑另一个
• 预期:第一次编辑已保存，第二次编辑开始
• 实际:第一次编辑取消，第二次编辑开始

打印出来:

before starting edit on : 1
start edit 1 on id: 13
cancel edit 0 on id: 14

...不幸的是，没有什么可以做的(甚至没有)...

您的示例略有修改:

import java.util.function.Function;

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.event.ActionEvent;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TablePosition;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 * https://stackoverflow.com/q/46396423/203657
 */
public class TableEditSO extends Application {

    @Override
    public void start(Stage primaryStage) {
        BorderPane root = new BorderPane();
        primaryStage.setScene(new Scene(root, 400, 400));
        primaryStage.show();
        //root.setCenter(new TableExample());
        root.setCenter(getContent());
    }

    private Parent getContent() {
        TableView<Building> tableView = new TableView<>();
        tableView.setEditable(true);

        //adds a new blank row to table;
        Button add = new Button("add");
        add.setOnAction(e -> {
            Building newBuilding = new Building();
            // modifications to the items will cancel an edit
            System.out.println("before adding: " + tableView.getEditingCell());
            tableView.getItems().add(0, newBuilding);
            tableView.edit(0, tableView.getColumns().get(0));

            //I tried focusing and selecting the row
            //but does not help.
            tableView.getFocusModel().focus(0);
            tableView.getSelectionModel().select(0);

        });

        Button edit = new Button("edit");
        edit.setOnAction(e -> {
            int size = tableView.getItems().size();
            if (size < 2) return;
            TablePosition pos = tableView.getEditingCell();
            int last = size - 1;
            if (pos != null) {
                int row = pos.getRow();
                if (row == last) {
                    //make certain we switch editing to another row
                    last--;
                }
            }
            System.out.println("before starting edit on : " + last);
            // starting edit on another item will cancel an edit
            tableView.edit(last, tableView.getColumns().get(0));
        });

        Building building = new Building();
        building.setName("Building 100");

        Function<Building, StringProperty> property = Building::nameProperty;

        TableColumn<Building, String> column = new TableColumn<>("name");
        column.setEditable(true);
        column.setCellValueFactory(cellData -> property.apply(cellData.getValue()));
        column.setCellFactory(p -> new EditingStringCell<>());

        tableView.getColumns().add(column);
        tableView.setItems(FXCollections.observableArrayList(building));

        VBox box = new VBox(10, add, edit, tableView);
        return box;
    }

    // don't extend without functional reason
    public class TableExample extends VBox {
        public TableExample() {
            TableView<Building> tableView = new TableView<>();
            tableView.setEditable(true);

            //adds a new blank row to table;
            Button add = new Button("add");
            add.setOnAction(e -> {
                Building newBuilding = new Building();
                System.out.println("before adding: " + tableView.getEditingCell());

                tableView.getItems().add(0, newBuilding);
                System.out.println("after adding: " + tableView.getEditingCell());
                tableView.edit(0, tableView.getColumns().get(0));
                System.out.println("after starting: " + tableView.getEditingCell());

                //I tried focusing and selecting the row
                //but does not help.
                tableView.getFocusModel().focus(0);
                tableView.getSelectionModel().select(0);

            });

            getChildren().addAll(add, tableView);

            Building building = new Building();
            building.setName("Building 100");

            Function<Building, StringProperty> property = Building::nameProperty;

            TableColumn<Building, String> column = new TableColumn<>("name");
            column.setEditable(true);
            column.setCellValueFactory(cellData -> property.apply(cellData.getValue()));
            column.setCellFactory(p -> new EditingStringCell<>());

            tableView.getColumns().add(column);
            tableView.setItems(FXCollections.observableArrayList(building));
        }
    }

    public static class EditingStringCell<S, T> extends TableCell<Building, String> {
        static int id ;
        private int myId;
        private TextField textField;

        public EditingStringCell() {
            // just to see re-use of cells
            myId = id++;
            setContentDisplay(ContentDisplay.TEXT_ONLY);
            // not needed, it's true by default
            // setEditable(true);
        }

        @Override
        protected void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            setText(empty ? null : item);
        }

        @Override
        public void startEdit() {
            super.startEdit();
            if (isEditing()) {
                System.out.println("start edit " + getIndex() + " on id: " + myId);
                updateEditControl(getItem());

            }
        }

        private void updateEditControl(String item) {
            if (textField == null) {
                textField = new TextField();   
                // always use the highest abstract available
                // so use action instead of keyEvent
                textField.setOnAction(this::handleAction);
                //textField.addEventHandler(KeyEvent.KEY_PRESSED, 
                //        this::handleKeyPressed);
                setGraphic(textField);
            }
            textField.setText(item == null ? "" : (item));
            setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
        }

        private void handleAction(ActionEvent ae) {
            commitEdit(textField.getText());

        }

        //whenever pressing enter on a new "blank" row
        //cancelEdit() gets called. But if you try again 
        //it works.
        private void handleKeyPressed(KeyEvent e) {
            if (e.getCode() == KeyCode.ENTER) {
                commitEdit(textField.getText());
            }
        }

        @Override
        public void cancelEdit() {
            super.cancelEdit();
            System.out.println("cancel edit " + getIndex() + " on id: " + myId);
            setContentDisplay(ContentDisplay.TEXT_ONLY);
        }

        @Override
        public void commitEdit(String newValue) {
            super.commitEdit(newValue);
            System.out.println("commited: " + newValue + " index: " + getIndex() + " on id: " + myId);
            setContentDisplay(ContentDisplay.TEXT_ONLY);
        }
    }

    public class Building {
        private final StringProperty name = new SimpleStringProperty();
        public StringProperty nameProperty() {
            return name;
        }
        public String getName() {
            return name.get();
        }
        public void setName(String name) {
            this.name.set(name);
        }
    }
    public static void main(String[] args) {launch(args);}
}