自动编号表行(javafx)

Question

我的问题是如何在第一列中使用tableRow的索引在JavaFX中创建一个新表.

所以我创建了一个类:NrCellFactory.

public class NrCellFactory<S, String> extends TableCellFactory<S,String> {

private class NrCell<S,String> extends TableCell<S,String>{

    public NrCell(){
        setText(this.getTableRow().getIndex()+"");
    }



}

@Override
protected TableCell<S, String> createTableCell(TableColumn<S, String> column) {
    return new NrCell();
}

}

然后我设置我的列应显示数字:

 nrCol.setCellFactory(new NrCellFactory<Person,String>());

当我加载项目时,nrCol没有数据......

有人能解决这个问题吗？

谢谢

Answer 1

样品溶液

这是使用单元工厂的解决方案:

TableColumn numberCol = new TableColumn("#");
numberCol.setCellValueFactory(new Callback<CellDataFeatures<Person, Person>, ObservableValue<Person>>() {
  @Override public ObservableValue<Person> call(CellDataFeatures<Person, Person> p) {
    return new ReadOnlyObjectWrapper(p.getValue());
  }
});

numberCol.setCellFactory(new Callback<TableColumn<Person, Person>, TableCell<Person, Person>>() {
  @Override public TableCell<Person, Person> call(TableColumn<Person, Person> param) {
    return new TableCell<Person, Person>() {
      @Override protected void updateItem(Person item, boolean empty) {
        super.updateItem(item, empty);

        if (this.getTableRow() != null && item != null) {
          setText(this.getTableRow().getIndex()+"");
        } else {
          setText("");
        }
      }
    };
  }
});
numberCol.setSortable(false);

简单的替代解决方案

还有一个更简单的示例使用单元格值工厂而没有单元工厂用于正常情况,其中表的后备数据列表中的所有项都是唯一的,并且可以通过以下方式查找其索引table.getItems().indexOf(p.getValue()):

TableColumn numberCol = new TableColumn("#");
numberCol.setCellValueFactory(new Callback<CellDataFeatures<Person, String>, ObservableValue<String>>() {
  @Override public ObservableValue<String> call(CellDataFeatures<Person, String> p) {
    return new ReadOnlyObjectWrapper(table.getItems().indexOf(p.getValue()) + "");
  }
});   
numberCol.setSortable(false);

为什么尝试这样做失败了

我无法确切地说为什么你的尝试失败了,因为我认为你的问题中没有足够的代码来准确诊断失败.我的猜测是你没有为行提供单元格值工厂,也没有在单元格的构造函数中设置文本而不是updateItem调用导致它无法工作.

可执行样本

这是一个可执行的示例:

import javafx.application.Application;
import javafx.beans.property.ReadOnlyObjectWrapper;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableColumn.CellDataFeatures;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import javafx.util.Callback;

public class NumberedTableViewSample extends Application {

    private TableView<Person> table = new TableView<Person>();
    private final ObservableList<Person> data =
        FXCollections.observableArrayList(
            new Person("Jacob", "Smith", "jacob.smith@example.com"),
            new Person("Isabella", "Johnson", "isabella.johnson@example.com"),
            new Person("Ethan", "Williams", "ethan.williams@example.com"),
            new Person("Emma", "Jones", "emma.jones@example.com"),
            new Person("Michael", "Brown", "michael.brown@example.com")
        );

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

    @Override
    public void start(Stage stage) {
        Scene scene = new Scene(new Group());
        stage.setTitle("Table View Sample");
        stage.setWidth(470);
        stage.setHeight(500);

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

        table.setEditable(true);

        TableColumn numberCol = new TableColumn("#");
        numberCol.setMinWidth(20);
        numberCol.setCellValueFactory(new Callback<CellDataFeatures<Person, Person>, ObservableValue<Person>>() {
            @Override public ObservableValue<Person> call(CellDataFeatures<Person, Person> p) {
                return new ReadOnlyObjectWrapper(p.getValue());
            }
        });

        numberCol.setCellFactory(new Callback<TableColumn<Person, Person>, TableCell<Person, Person>>() {
            @Override public TableCell<Person, Person> call(TableColumn<Person, Person> param) {
                return new TableCell<Person, Person>() {
                    @Override protected void updateItem(Person item, boolean empty) {
                        super.updateItem(item, empty);

                        if (this.getTableRow() != null && item != null) {
                            setText(this.getTableRow().getIndex()+"");
                        } else {
                            setText("");
                        }
                    }
                };
            }
        });
        numberCol.setSortable(false);

        TableColumn firstNameCol = new TableColumn("First Name");
        firstNameCol.setMinWidth(100);
        firstNameCol.setCellValueFactory(
                new PropertyValueFactory<Person, String>("firstName"));

        TableColumn lastNameCol = new TableColumn("Last Name");
        lastNameCol.setMinWidth(100);
        lastNameCol.setCellValueFactory(
                new PropertyValueFactory<Person, String>("lastName"));

        TableColumn emailCol = new TableColumn("Email");
        emailCol.setMinWidth(200);
        emailCol.setCellValueFactory(
                new PropertyValueFactory<Person, String>("email"));

        table.setItems(data);
        table.getColumns().addAll(numberCol, firstNameCol, lastNameCol, emailCol);

        final VBox vbox = new VBox();
        vbox.setSpacing(5);
        vbox.setPadding(new Insets(10, 0, 0, 10));
        vbox.getChildren().addAll(label, table);

        ((Group) scene.getRoot()).getChildren().addAll(vbox);
        stage.setScene(scene);
        stage.show();
    }

    public static class Person {

        private final SimpleStringProperty firstName;
        private final SimpleStringProperty lastName;
        private final SimpleStringProperty email;

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

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

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

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

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

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

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

Answer 2

在java 8中,使用lambda表达式可以更轻松地完成:

TableColumn<Person, Number> indexColumn = new TableColumn<Person, Number>("#");
indexColumn.setSortable(false);
indexColumn.setCellValueFactory(column-> new ReadOnlyObjectWrapper<Number>(YourTable.getItems().indexOf(column.getValue())));