Adding a listener for canceling selection in ListView (JavaFX)

Question

Nowadays I am practicing JavaFX. And I have a problem about ListView. I can make a listener for multiple selections of ListView. However, when I cancel the selection, the listener I made doesn't reflect the cancellation. How can I make a listener that reflects it? The following is a listener that I made.

ListView<String> lv = new ListView<>(FXCollections.observableArrayList(stringArray));  // stringArray is an array that I made.

lv.getSelectionModel().selectedItemProperty().addListener(ch -> {
        System.out.println("size: " + lv.getSelectionModel().getSelectedIndices().size());
    });

Answer 1

如果在启用多项选择时选择了更改，请在ListChangeListener列表中添加selectedItems（注意selectedItems，而不是selectedItem）：

lv.getSelectionModel().getSelectedItems().addListener(
    (ListChangeListener.Change<? extends String> ch) -> {
        System.out.println("size: " + lv.getSelectionModel().getSelectedIndices().size());
    }
);

请注意，如果您仅对选择为空感兴趣，则可以

Bindings.isEmpty(lv.getSelectionModel().getSelectedItems()).addListener(
    (obs, selectionWasEmpty, selectionIsNowEmpty) -> {
        if (selectionIsNowEmpty) {
            System.out.println("Nothing is selected");
        } else {
            System.out.println("Something is selected");
        }
    }
);