java - MultipleSelectionModel:哪个列表更改事件可以从 selectedIndices 中获得？

Question

...特别是在修改基础项目时？

下面是一个快速示例，它选择一个范围并在 TableView 和 ListView 的选择上方添加一个项目。添加前后的selectedIndices:

indices before modification: [2, 3]
indices after modification: [3, 4]

预期选项:

• 在整个范围内更换了一个
• 为“2”删除了一个，为“4”添加了一个
• ??

实际:

• 表的选择会触发两个事件，每个事件都有一个 wasAdded
• list 的选择触发了一个 wasPermutated(这太疯狂了，或者我错过了什么？)

输出(jdk8u40b12):

Change #0 on TableView indices 
list = [3]
    Change event data:

 class javafx.scene.control.MultipleSelectionModelBase$3
 javafx.scene.control.MultipleSelectionModelBase$3@4ececa
    cursor = 0
        Kind of change: added
        Affected range: [0, 1]
        Added size: 1
        Added sublist: [3]

Change #1 on TableView indices 
list = [3, 4]
    Change event data:

 class javafx.scene.control.MultipleSelectionModelBase$3
 javafx.scene.control.MultipleSelectionModelBase$3@b0161d
    cursor = 0
        Kind of change: added
        Affected range: [1, 2]
        Added size: 1
        Added sublist: [4]

Change #0 on ListView indices 
list = [3, 4]
    Change event data:

 class com.sun.javafx.collections.NonIterableChange$SimplePermutationChange
 { permutated by [4, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0] }
    cursor = 0
        Kind of change: permutated
        Affected range: [0, 2]
        Permutation: [0->4, 1->3]

生成代码:

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.collections.ListChangeListener.Change;
import javafx.scene.control.ListView;
import javafx.scene.control.SelectionMode;
import javafx.scene.control.TableView;
import javafx.stage.Stage;

public class SelectedIndicesOnItemsModified extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        ObservableList<Integer> items = FXCollections.observableArrayList(1, 2, 3, 4);
        TableView<Integer> table = new TableView<>(items);
        table.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
        table.getSelectionModel().selectRange(2, 4);
        System.out.println("indices before modification: " + 
            table.getSelectionModel().getSelectedIndices());
        ListView<Integer> list = new ListView<>(items);
        list.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
        list.getSelectionModel().selectRange(2, 4);

        new PrintingListChangeListener("TableView indices ", 
             table.getSelectionModel().getSelectedIndices());        
        new PrintingListChangeListener("ListView indices ", 
             list.getSelectionModel().getSelectedIndices());  
        items.add(0, 111);
    }

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

    public static <T> void prettyPrint(Change<? extends T> change) {
        StringBuilder sb = new StringBuilder("\tChange event data:\n");
        sb.append("\n " + change.getClass() + "\n " + change);
        int i = 0;
        change.reset();
        while (change.next()) {
            sb.append("\n\tcursor = ").append(i++).append("\n");

            final String kind = change.wasPermutated() ? "permutated" : change
                    .wasReplaced() ? "replaced"
                    : change.wasRemoved() ? "removed"
                            : change.wasAdded() ? "added"
                                    : change.wasUpdated() ? "updated" : "none";
            sb.append("\t\tKind of change: ").append(kind).append("\n");

            sb.append("\t\tAffected range: [").append(change.getFrom())
                    .append(", ").append(change.getTo()).append("]\n");

            if (kind.equals("added") || kind.equals("replaced")) {
                sb.append("\t\tAdded size: ").append(change.getAddedSize())
                        .append("\n");
                sb.append("\t\tAdded sublist: ")
                        .append(change.getAddedSubList()).append("\n");
            }

            if (kind.equals("removed") || kind.equals("replaced")) {
                sb.append("\t\tRemoved size: ").append(change.getRemovedSize())
                        .append("\n");
                sb.append("\t\tRemoved: ").append(change.getRemoved())
                        .append("\n");
            }

            if (kind.equals("permutated")) {
                StringBuilder permutationStringBuilder = new StringBuilder("[");
                for (int k = change.getFrom(); k < change.getTo(); k++) {
                    permutationStringBuilder.append(k).append("->")
                            .append(change.getPermutation(k));
                    if (k < change.getTo() - 1) {
                        permutationStringBuilder.append(", ");
                    }
                }
                permutationStringBuilder.append("]");
                String permutation = permutationStringBuilder.toString();
                sb.append("\t\tPermutation: ").append(permutation).append("\n");
            }
        }
        System.out.println(sb.toString());
    };

    public static class PrintingListChangeListener implements ListChangeListener {
        String source;
        int counter;
        public PrintingListChangeListener() {
        }

        public PrintingListChangeListener(String message, ObservableList<?> list) {
            list.addListener(this);
            source = message;
        }
        @Override
        public void onChanged(Change change) {
            System.out.println("Change #" + counter++ + " on " +source + 
                 "\nlist = " + change.getList());
            prettyPrint(change);
        }
    }

}

提交了两个问题，RT-39393对于 ListView ，RT-39394对于 TableView

Answer 1

对我自己的问题的初步部分回答

通知计数

在伪代码中，通知的数量(又名:调用 changed(Change c))应该与基础数据中的数量相同

itemsChanges = 0; 
itemsListener = c -> itemsChanges++;
getItems().addListener(itemsListener);
selectedChanges = 0; 
selectedListener = c -> selectedChanges++; 
getSelectedIndices().addListener(selectedListener);
getItems().modifySomehow(...); 
assertEquals(itemsChanges, selectedChanges);

变化类型

仔细想想，底层项目的大部分变化似乎都映射到 selectedIndices 中的替换项(下面的“值”表示 selectedIndices 中的元素):

"real"wasAdded:所有大于插入位置的值都必须增加 addedSize

// selectedIndices before
[2, 4]
items.add(0, something);
// selectedIndices after
[3, 5]

-> 净效果:两个值被设置(==替换为)一个新值

"real"wasRemoved:所有指向已删除项目的值也必须被删除，大于删除位置的值必须减少 removedSize

// selectedIndices before
[2, 4, 5, 8]
items.removeAll(items.get(3), items.get(5))
// selectedIndices after
[2, 3, 6]

-> 净效果:将位置 1 的 [4, 5, 8] 替换为 [3, 6]

wasUpdated:索引未更改，但基础项目确实以某种方式发生了变化。根据上下文，将这些更新传递给或不传递给它的监听器可能是个好主意。

仍然开放:项目中的替换/排列

要获得那些预期的(至少通过我的论文编码 :-) 正确的通知，不是很简单 - 并且在 MultipleSelectionModelBase 和子类中出错。目前正在尝试将所有令人讨厌的细节移到专用的 IndicesList 中(这是一个以项目作为源列表的 TransformList)