如何添加监听器复选框使用CheckBoxListCell一个ListView内 [英] How to add listener to the checkbox inside a listview that uses CheckBoxListCell

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<一复选框相关联的对象的可观察属性href=\"http://docs.oracle.com/javase/8/javafx/api/javafx/scene/control/cell/CheckBoxListCell.html#forListView-javafx.util.Callback-\">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<一个描述href=\"http://docs.oracle.com/javase/8/javafx/api/javafx/scene/control/cell/CheckBoxListCell.html#forListView-javafx.util.Callback-\">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）。

getSelectedProperty - A Callback that, given an object of type T (which is a value taken out of the ListView.items list), will return an ObservableValue that represents whether the given item is selected or not. This ObservableValue will be bound bidirectionally (meaning that the CheckBox in the cell will set/unset this property based on user interactions, and the CheckBox will reflect the state of the ObservableValue, if it changes externally).

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.

这篇关于如何添加监听器复选框使用CheckBoxListCell一个ListView内的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！