JavaFx：如何在listView中显示和隐藏滚动条？

Question

当鼠标指针不在列表视图中时如何隐藏滚动条？ 并在我的鼠标指针位于列表视图时显示滚动条。

Answer 1

仅使用ListView很难，而且我不确定是否有可能，因为ListView会根据需要显示滚动条，而且似乎无法访问滚动条（请参阅此文章 ）。

但是有一种使用ScrollPane的解决方法：1.将ListView放入ScrollPane中。2.调整ListView的大小，使其始终足够大以显示内容（如果没有足够的空间，它将在ScrollPane中展开） ）3.仅在用鼠标悬停时才使ScrollPane的滚动条出现

我测试了一个示例：

用于启动测试应用程序的Application类：

package listViewScrollbar;

import java.net.URL;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class ListViewScrollbarApplication extends Application {

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

    @Override
    public void start(Stage primaryStage) {
        try {
            URL fxmlUrl = getClass().getResource("ListViewScrollbarTest.fxml");
            FXMLLoader fxmlLoader = new FXMLLoader(fxmlUrl);
            ListViewScrollbarController controller = new ListViewScrollbarController();
            fxmlLoader.setController(controller);
            Parent root = fxmlLoader.load();
            Scene scene = new Scene(root, 200, 300);
            scene.getStylesheets().add(getClass().getResource("ListViewScrollbar.css").toExternalForm());
            primaryStage.setScene(scene);
            primaryStage.show();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

fxml文件：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.ListView?>
<?import javafx.scene.control.ScrollPane?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.BorderPane?>

<AnchorPane xmlns="http://javafx.com/javafx/10.0.1" xmlns:fx="http://javafx.com/fxml/1">
   <children>
      <BorderPane layoutX="-89.0" layoutY="-123.0" prefHeight="300.0" prefWidth="400.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
         <center>
            <ScrollPane fx:id="scrollPane" BorderPane.alignment="CENTER">
               <content>
                  <ListView fx:id="listView" prefHeight="500.0" prefWidth="500.0" />
               </content>
            </ScrollPane>
         </center>
      </BorderPane>
   </children>
</AnchorPane>

示例控制器：

package listViewScrollbar;

import java.net.URL;
import java.util.ResourceBundle;

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.ListView;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.ScrollPane.ScrollBarPolicy;

public class ListViewScrollbarController implements Initializable {

    @FXML
    private ListView<String> listView;
    @FXML
    private ScrollPane scrollPane;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        //just add some text for the example
        ObservableList<String> strings = FXCollections.observableArrayList("String 1",
                "A very long String ...............................................................", "String 3", "Another String");
        listView.setItems(strings);

        //here you enable and disable the scroll bars depending on the mouse hovering the list view
        scrollPane.setOnMouseEntered(e -> {
            scrollPane.setHbarPolicy(ScrollBarPolicy.ALWAYS);
            scrollPane.setVbarPolicy(ScrollBarPolicy.ALWAYS);
        });
        scrollPane.setOnMouseExited(e -> {
            scrollPane.setHbarPolicy(ScrollBarPolicy.NEVER);
            scrollPane.setVbarPolicy(ScrollBarPolicy.NEVER);
        });
    }
}

现在，只要ListView的大小足以显示此替代方法应执行的内容。