单击时取消选择 javafx ListView 上的项目 [英] Deselect an item on an javafx ListView on click

问题描述

我在 JavaFX 应用程序中使用 ListView 控件.它被设置为 MULTIPLE 选择模式.我知道作为用户，我可以按住 Ctrl 键单击一个项目来取消选择它，但这对我的用户来说不够直观.我想要一种再次单击以取消选择它的方法.换句话说，单击一次 - 选择；单击所选项目，它会变为未选中状态.

I'm using a ListView control in a JavaFX application. It is set for MULTIPLE selection mode. I know as a user, I can Ctrl-Click an item to deselect it, but this is not intuitive enough for my users. I want a way to click a second time to deselect it. In other words click once - select; click selected item and it becomes unselected.

我尝试使用 ChangeListener 和 onMouseClicked 事件.两者都工作得很好.下面是每个的代码片段.

I've tried using both a ChangeListener and an onMouseClicked event. Neither works very well. Below are code snippets of each.

变更监听器:

效果 - 从不选择列表中的第一项.我点击它，它保持未点击状态.对项目 2..n 没有影响

effect - first item in the list is NEVER selected. I click on it and it stays unclicked. No effect on items 2..n

listView.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<SpecificAlgorithmData>() {
    @Override
    public void changed(final ObservableValue observableValue, final SpecificAlgorithmData oldData, final SpecificAlgorithmData newData) {

        //if already selected then deselect it
        int selectedIndex = listView.getSelectionModel().getSelectedIndex();
        System.out.println("selected " + selectedIndex);
        System.out.println("all selected" + listView.getSelectionModel().getSelectedIndices());
        if (!selecting && !listView.getSelectionModel().getSelectedIndices().contains(selectedIndex)){


            Iterator <Integer> iterator = listView.getSelectionModel().getSelectedIndices().iterator();
            selecting = true;
            listView.getSelectionModel().select(-1);//deselect all

            while (iterator.hasNext()){
                int index = iterator.next();
                if (index!= selectedIndex){
                    listView.getSelectionModel().select(index);
                }
            }
            selecting = false;
        }
    }
}

点击:

没有效果，因为我不确定如何获取我刚刚点击的索引.由于是硬编码，因此根本不允许选择第 2 项.

No effect, since I'm not sure how to get the index of the one I just clicked. Being hard coded, this simply disallows of ever selecting item 2.

listView.setOnMouseClicked(new EventHandler<MouseEvent>() {
    @Override
    public void handle(final MouseEvent mouseEvent) {
        int selectedItem = 2; //FIXME: How to I get the index of clicked item?
        if (listView.getSelectionModel().isSelected(selectedItem)){
            listView.getSelectionModel().clearSelection(selectedItem);
        }
    }
});

推荐答案

在 JavaFX 中更改控件的行为非常困难 - 目前 API 中确实没有挂钩到行为类中.

Changing the behavior of controls in JavaFX is pretty difficult - there are really no hooks currently in the API into the behavior classes.

通过使用列表中的单元格注册事件过滤器，直接实现选择行为并使用事件，以下似乎有效.

The following seems to work, by registering an event filter with the cells in the list, implementing the selection behavior directly, and consuming the event.

虽然感觉有点脆弱(例如，如果未来版本决定在单击鼠标而不是按下鼠标时实现默认行为会怎样；或者也许更好，如果未来版本决定添加由鼠标处理的附加功能会怎样?事件).因此，请使用此解决方案并附上一些买家注意"通知.

It feels a bit fragile though (what if a future release decided to implement the default behavior on mouse clicked, instead of mouse pressed, for example; or perhaps better, what if a future release decided to add additional functionality handled by mouse events). So use this solution with a bit of a "buyer beware" notice attached.

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.control.MultipleSelectionModel;
import javafx.scene.control.SelectionMode;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

public class DeselectableList extends Application {

    @Override
    public void start(Stage primaryStage) {
        ListView<String> list = new ListView<>();
        MultipleSelectionModel<String> selectionModel = list.getSelectionModel();
        selectionModel.setSelectionMode(SelectionMode.MULTIPLE);
        for (int i=1; i<=20; i++) {
            list.getItems().addAll("Item "+i);
        }
        list.setCellFactory(lv -> {
            ListCell<String> cell = new ListCell<>();
            cell.textProperty().bind(cell.itemProperty());
            cell.addEventFilter(MouseEvent.MOUSE_PRESSED, event -> {
                list.requestFocus();
                if (! cell.isEmpty()) {
                    int index = cell.getIndex();
                    if (selectionModel.getSelectedIndices().contains(index)) {
                        selectionModel.clearSelection(index);
                    } else {
                        selectionModel.select(index);
                    }
                    event.consume();
                }
            });
            return cell ;
        });
        BorderPane root = new BorderPane(list);
        Scene scene = new Scene(root, 150, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

显然你比我更了解你的用户，但我可能更喜欢在 ListView 上有一个很好的工具提示，向他们解释如何使用它...

Obviously you know your users better than I, but I might prefer just to have a nice tooltip on the ListView explaining to them how to use it...

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