Javafx链接/将Treeview项绑定到ObservableList

Question

我试图找到一种简单的方法来链接下载类型的树视图到相同类型的可观察列表。

主控制器。JAVA

public class MainController {

    private ObservableList<Download> downloads = FXCollections.observableArrayList();
    @FXML private TreeView<Download> $TreeDownloads;

    @FXML
    public void initialize() {
        $TreeDownloads.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
        $TreeDownloads.setNodeOrientation(NodeOrientation.LEFT_TO_RIGHT);
        $TreeDownloads.setShowRoot(false);

        downloads.addListener(new ListChangeListener<Download>() {
            @Override
            public void onChanged(Change<? extends Download> c) {
                if (c.wasAdded()) {
                    addDownloads(c.getAddedSubList());
                }
                if (c.wasRemoved()) {
                    //
                }
            }
        });
        downloads.add(new Download("3847"));
        downloads.add(new Download("3567"));
        downloads.add(new Download("2357"));
    }

    private void addDownloads(List<? extends Download> downloads) {
        downloads.forEach(download -> {
            TreeItem<Download> treeItem = new TreeItem<>(download);
            $TreeDownloads.getRoot().getChildren().add(treeItem);
            new Thread(download::start).start();
        });
    }

    private void removeDownloads(List<? extends Download> downloads) {
        // remove treeitems from the treeview that hold these downloads
    }
}

Download.java

public class Download {

    private DoubleProperty progress = new SimpleDoubleProperty(0D);
    private StringProperty id = new SimpleStringProperty("");

    public Download(String id) {
        this.id.set(id);
    }

    public void start() {
        while (progress.getValue() < 1) {
            try {
                Thread.sleep(1000);
                progress.add(0.1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }      

    @Override
    public String toString() {
        return id.getValue();
    }
}

如何实现按对象删除（下载）机制，是否有更简单的方法将observablelist的项绑定到treeview？

Answer 1

仍然不能完全确定确切的问题是什么，所有这些都非常简单：

首先，您的列表更改监听器实现是不正确的，它必须在访问其状态之前推进子更改（您是否运行了发布的代码；）

downloads.addListener(new ListChangeListener<Download>() {
    @Override
    public void onChanged(Change<? extends Download> c) {
        // this while was missing
        while (c.next()) {
            if (c.wasAdded()) {
                addDownloads(c.getAddedSubList());
            }
            if (c.wasRemoved()) {
                // accessing the list of removed elements is .. plain standard api 
                removeDownloads(c.getRemoved());
            }

        }
    }
});

现在实现相应树项的移除：

private void removeDownloads(List<? extends Download> downloads) {
    // remove treeitems from the treeview that hold these downloads
    List<TreeItem<Download>> treeItemsToRemove = treeDownloads.getRoot().getChildren().stream()
            .filter(treeItem -> downloads.contains(treeItem.getValue()))
            .collect(Collectors.toList());
    treeDownloads.getRoot().getChildren().removeAll(treeItemsToRemove);
}

旁白：

• java命名约定对成员使用小写字母：treeDownloads（不是$treeDownloads）