如何添加监听器复选框使用CheckBoxListCell一个ListView内

问题描述

我有一个使用旁边的项 CheckBoxListCell 来显示与复选框列表列表视图。如何将侦听器添加到该复选框，当作为一个项目被选中或未被选中知道吗？

I have a listview that uses a CheckBoxListCell to display a list with checkboxes next to the items. How do I add a listener to this checkbox to know when an item as been selected or unselected?

推荐答案

解决方案

您不要将监听器添加到复选框。你一个侦听器添加到将其与由CheckBoxListCell.forListView例程。

You don't add a listener to the checkbox. You add a listener to the observable property of the object which was associated with the checkbox by the CheckBoxListCell.forListView routine.

设置的关联：

ListView<Task> checklist = new ListView<>(tasks);
checklist.setCellFactory(CheckBoxListCell.forListView(Task::selectedProperty));

添加一个侦听所有项目：

Adding a listener for all items:

tasks.forEach(task -> task.selectedProperty().addListener((observable, wasSelected, isSelected) -> {
    if (isSelected) {
        // . . .
    } else {
        // . . .
    }
}));

文档

的方法，在CheckBoxListCell.forListView javadoc中像这样：

The process is described in the CheckBoxListCell.forListView javadoc like so:

getSelectedProperty - 一个回调，鉴于T类型的对象
  （这是取出的ListView.items列表的值），将
  返回重新presents是否给予ObservableValue
  项目选择或没有。这ObservableValue将被绑定
  双向（即单元格中的复选框将设置/取消
  这个属性基于用户的互动，以及该复选框会
  反映ObservableValue的状态，如果外部变化）。

示例程序

这表明一些可能与CheckBoxListCell使用模式的样本程序：

A sample program which demonstrated some of the patterns which could be used with CheckBoxListCell:

import javafx.application.Application;
import javafx.beans.property.*;
import javafx.collections.*;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.ListView;
import javafx.scene.control.cell.CheckBoxListCell;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import javafx.util.StringConverter;

import java.util.*;
import java.util.stream.Collectors;

public class CheckList extends Application {
    @Override
    public void start(Stage stage) throws Exception{
        ObservableList<Task> tasks = FXCollections.observableArrayList(
                Arrays.stream(taskNames).map(Task::new).collect(Collectors.toList())
        );

        ListView<String> reactionLog = new ListView<>();
        tasks.forEach(task -> task.selectedProperty().addListener((observable, wasSelected, isSelected) -> {
            if (isSelected) {
                reactionLog.getItems().add(reactionStrings.get(task.getName()));
                reactionLog.scrollTo(reactionLog.getItems().size() - 1);
            }
        }));

        ListView<Task> checklist = new ListView<>(tasks);
        checklist.setCellFactory(CheckBoxListCell.forListView(Task::selectedProperty, new StringConverter<Task>() {
            @Override
            public String toString(Task object) {
                return object.getName();
            }

            @Override
            public Task fromString(String string) {
                return null;
            }
        }));

        HBox layout = new HBox(10, checklist, reactionLog);
        layout.setPrefSize(350, 150);
        layout.setPadding(new Insets(10));
        Scene scene = new Scene(layout);
        stage.setScene(scene);
        stage.show();
    }

    public static class Task {
        private ReadOnlyStringWrapper name = new ReadOnlyStringWrapper();
        private BooleanProperty selected = new SimpleBooleanProperty(false);

        public Task(String name) {
            this.name.set(name);
        }

        public String getName() {
            return name.get();
        }
        public ReadOnlyStringProperty nameProperty() {
            return name.getReadOnlyProperty();
        }

        public BooleanProperty selectedProperty() {
            return selected;
        }
        public boolean isSelected() {
            return selected.get();
        }
        public void setSelected(boolean selected) {
            this.selected.set(selected);
        }
    }

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

    private static final String[] taskNames = {
            "Walk the dog",
            "Skin the cat",
            "Feed the pig"
    };

    private static final Map<String, String> reactionStrings = new HashMap<>();
    static {
        reactionStrings.put("Walk the dog", "The dog thanks you");
        reactionStrings.put("Skin the cat", "The cat hates you");
        reactionStrings.put("Feed the pig", "The pig wants more");
    }
}

选择第一个项目一次，第三项三次后

示例输出。

Sample output after selecting the first item once and the third item three times.

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